Part I. THE SUBJECTIVE CONDITIONS OF EVIDENCE: THE MENTAL ACTIVITIES OF THE JUDGE. (continued 4)

The second part of the work turns upon the suspicion of a definite person when his own activity is interpolated as a cause of the crime. Under some conditions again, the effect of the crime on the criminal has to be examined, i.e., enrichment, deformation, emotional state, etc. But the evidence of guilt is established only when the crime is accurately and explicitly described as the inevitable result of the activity of the criminal and his activity only. This systematic work of observing and correlating every instant of the supposed activities of the accused (once the situation of the crime is defined as certainly as possible), is as instructive as it is promising of success. It is the one activity which brings us into touch with bare perception and its reproduction. “All inference with regard to facts appears to depend upon the relation of cause to effect; by virtue of this relation alone may we rely upon the evidence of our memories and our senses.”[131] Hume illustrates this remark with the following example: If a clock or some other machine is found on a desert island, the conclusion is drawn that men are or were on the island. The application is easy enough. The presence of a clock, the presence of a three-cornered wound is perceived by the senses—that men were there, that the wound was made with a specific kind of instrument, is a causal inference. Simple as this proposition of Hume’s is, it is of utmost importance in the law because of the permanent and continually renewed problems: What is the effect in this case? What is the cause? Do they belong together? Remembering that these questions make our greatest tasks and putting them, even beyond the limit of disgust, will save us from grave errors.

There is another important condition to which Hume calls attention and which is interpreted by his clever disciple Meinong. It is a fact that without the help of previous experience no causal nexus can be referred to an observation, nor can the presence of such be discovered in individual instances. It may be postulated only. A cause is essentially a complex in which every element is of identical value. And this circumstance is more complicated than it appears to be, inasmuch as it requires reflection to distinguish whether only one or more observations have been made. Strict self-control alone and accurate enumeration and supervision will lead to a correct decision as to whether one or ten observations have been made, or whether the notion of additional observations is not altogether illusory.

This task involves a number of important circumstances. First of all must be considered the manner in which the man on the street conceives the causal relation between different objects. The notion of causality, as Schwarz[132] shows, is essentially foreign to the man on the street. He is led mainly by the analogy of natural causality with that of human activity and passivity, e.g., the fire is active with regard to water, which simply must sizzle passively. This observation is indubitably correct and significant, but I think Schwarz wrong to have limited his description to ordinary people; it is true also of very complex natures. It is conceivable that external phenomena shall be judged in analogy with the self, and inasmuch as the latter often appears to be purely active, it is also supposed that those natural phenomena which appear to be especially active are really so.

In addition, many objects in the external world with which we have a good deal to do, and are hence important, do as a matter of fact really appear to be active—the sun, light, warmth, cold, the weather, etc., so that we assign activity and passivity only according to the values the objects have for us. The ensuing mistake is the fact that we overlook the alternations between activity and passivity, or simply do not make the study such alternations require; yet the correct apportionment of action and reaction is, for us, of greatest importance. In this regard, moreover, there is always the empty problem as to whether two things may stand in causal relation,—empty, because the answer is always yes. The scientific and practical problem is as to whether there exists an actual causal nexus. The same relation occurs in the problem of reciprocal influences. No one will say, for example, that any event exercises a reciprocal influence on the sun, but apart from such relatively few cases it would not only be supposed that A is the cause of the effect B, but also that B might have reciprocally influenced A. Regard for this possibility may save one from many mistakes.

One important source of error with regard to cause and effect lies in the general and profound supposition that the cause must have a certain similarity to the effect. So Ovid, according to J. S. Mill, has Medea brew a broth of long-lived animals; and popular superstitions are full of such doctrine. The lung of a long-winded fox is used as a cure for asthma, the yarrow is used to cure jaundice, agaricos is used for blisters, aristolochia (the fruit of which has the form of a uterus) is used for the pains of child-birth, and nettle-tea for nettle-rash. This series may be voluntarily increased when related to the holy patron saints of the Catholic Church, who are chosen as protectors against some especial condition or some specific difficulty because they at one time had some connection with that particular matter. So the holy Odilia is the patron saint for diseases of the eye, not because she knew how to cure the eyes, but because her eyes were put out with needles. The thief Dismas is the patron of the dying because we know nothing about him save that he died with Christ. St. Barbara, who is pictured together with a tower in which she was imprisoned, and which was supposed to be a powder house, has become the patron saint of artillery. In the same manner St. Nicholas is, according to Simrock, the patron of sailors because his name resembles Nichus, Nicor, Nicker, which is the name of the unforgotten old German sea-deity.

Against such combinations, external and unjustified, not even the most educated and skilful is safe. Nobody will doubt that he is required to make considerable effort in his causal interpretation because of the sub-conscious influence of such similarities. The matter would not be so dangerous, all in all, because such mistakes may be easily corrected and the attention of people may be called to the inadequacy of such causation—but the reason for this kind of correlations is rarely discovered. Either people do not want to tell it because they instinctively perceive that their causal interpretation cannot be justified, or they cannot even express it because the causal relation had been assumed only subconsciously, and they are hence unaware of the reasons for it and all the more convinced that they are right. So for example, an intelligent man told me that he suspected another of a murder because the latter’s mother died a violent death. The witness stuck to his statement: “the man who had once had something to do with killing must have had something to do with this killing.” In a similar manner, a whole village accused a man of arson because he was born on the night on which a neighboring village burned down. Here, however, there was no additional argument in the belief that his mother had absorbed the influence of the fire inasmuch as the latter was told that there had been a fire only after the child was born. “He once had something to do with fire,” was the basis of the judgment, also in this case.

There are innumerable similar examples which, with a large number of habitual superstitious presuppositions, make only false causality. Pearls mean tears because they have similar form; inasmuch as the cuckoo may not without a purpose have only two calls at one time and ten or twenty at another, the calls must mean the number of years before death, before marriage, or of a certain amount of money, or any other countable thing. Such notions are so firmly rooted in the peasantry and in all of us, that they come to the surface, whether consciously or unconsciously, and influence us more than we are accustomed to suppose they do. Whenever anybody assures us that he is able to assert absolutely, though not altogether prove a thing, this assurance may be variously grounded, but not rarely it is no more than one of these false correlations. Schopenhauer has said, that “motivation is causality seen from within,”—and one may add conversely that causality is motivation seen from without. What is asserted must be motivated, and that is done by means of causality—if no real ultimate cause is found a false, superficial and insufficient one is adopted, inasmuch as we ever strive to relate things causally, in the knowledge that, otherwise, the world would be topsy-turvy. “Everywhere,” says Stricker, “we learn that men who do not associate their experiences according to right cause are badly adapted to their environment; the pictures of artists are disliked, the laborer’s work does not succeed; the tradesman loses his money, and the general his battle.” And we may add, “The criminalist his case.” For whoever seeks the reason for a lost case certainly will find it in the ignorance of the real fact and in the incorrect coördination of cause and effect. The most difficult thing in such coördination is not that it has to be tested according to the notion one has for himself of the chain of events; the difficulty lies in the fact that the point of view and mental habits of the man who is suspected of the effects must be adopted. Without this the causal relations as they are arrived at by the other can never be reached, or different results most likely ensue.

The frequency of mistakes like those just mentioned is well known. They affect history. Even La Rochefoucauld was of the opinion that the great and splendid deeds which are presented by statesmen as the outcome of far-reaching plans are, as a rule, merely the result of inclination and passion. This opinion concerns the lawyer’s task also, for the lawyer is almost always trying to discover the moving, great, and unified plan of each crime, and in order to sustain such a notion, prefers to perfect a large and difficult theoretic construction, rather than to suppose that there never was a plan, but that the whole crime sprang from accident, inclination, and sudden impulse. The easiest victims in this respect are the most logical and systematic lawyers; they merely presuppose, “I would not have done this” and forget that the criminal was not at all so logical and systematic, that he did not even work according to plan, but simply followed straying impulses.

Moreover, a man may have determined his causal connections correctly, yet have omitted many things, or finally have made a voluntary stop at some point in his work, or may have carried the causal chain unnecessarily far. This possibility has been made especially clear by J. S. Mill, who showed that the immediately preceding condition is never taken as cause. When we throw a stone into the water we call the cause of its sinking its gravity, and not the fact that it has been thrown into the water. So again, when a man falls down stairs and breaks his foot, in the story of the fall the law of gravity is not mentioned; it is taken for granted. When the matter is not so clear as in the preceding examples, such facts are often the cause of important misunderstandings. In the first case, where the immediately preceding condition is not mentioned, it is the inaccuracy of the expression that is at fault, for we see that at least in scientific form, the efficient cause is always the immediately preceding condition. So the physician says, “The cause of death was congestion of the brain in consequence of pressure resulting from extravasation of the blood.” And he indicates only in the second line that the latter event resulted from a blow on the head. In a similar manner the physicist says that the board was sprung as a consequence of the uneven tension of the fibers; he adds only later that this resulted from the warmth, which again is the consequence of the direct sunlight that fell on the board. Now the layman had in both cases omitted the proximate causes and would have said in case 1, “The man died because he was beaten on the head,” and in case 2, “The board was sprung because it lay in the sun.” We have, therefore, to agree to the surprising fact that the layman skips more intermediaries than the professional, but only because either he is ignorant of or ignores the intervening conditions. Hence, he is also in greater danger of making a mistake through omission.

Inasmuch as the question deals only with the scarcity of correct knowledge of proximate causes, we shall set aside the fact that lawyers themselves make such mistakes, which may be avoided only by careful self-training and cautious attention to one’s own thoughts. But we have at the same time to recognize how important the matter is when we receive long series of inferences from witnesses who give expression only to the first and the last deduction. If we do not then examine and investigate the intermediary links and their justification, we deserve to hear extravagant things, and what is worse, to make them, as we do, the foundation of further inference. And once this is done no man can discover where the mistake lies.

If again an inference is omitted as self-evident (cf. the case of gravity, in falling down stairs) the source of error and the difficulty lies in the fact that, on the one hand, not everything is as self-evident as it seems; on the other, that two people rarely understand the same thing by “self-evident,” so that what is self-evident to one is far from so to the other. This difference becomes especially clear when a lawyer examines professional people who can imagine offhand what is in no sense self-evident to persons in other walks of life. I might cite out of my own experience, that the physicist Boltzmann, one of the foremost of living mathematicians, was told once upon a time that his demonstrations were not sufficiently detailed to be intelligible to his class of non-professionals, so that his hearers could not follow him. As a result, he carefully counted the simplest additions or interpolations on the blackboard, but at the same time integrated them, etc., in his head, a thing which very few people on earth can do. It was simply an off-hand matter for this genius to do that which ungenial mortals can not.

This appears in a small way in every second criminal case. We have only to substitute the professionals who appear as witnesses. Suppose, e.g., that a hunter is giving testimony. He will omit to state a group of correlations; with regard to things which are involved in his trade, he will reach his conclusion with a single jump. Then we reach the fatal circle that the witness supposes that we can follow him and his deductions, and are able to call his attention to any significant error, while we, on the other hand, depend on his professional knowledge, and agree to his leaping inferences and allow his conclusions to pass as valid without knowing or being able to test them.

The notion of “specialist” or “professional” must be applied in such instances not only to especial proficients in some particular trade, but also to such people as have by accident merely, any form of specialized knowledge, e.g., knowledge of the place in which some case had occurred. People with such knowledge present many a thing as self-evident that can not be so to people who do not possess the knowledge. Hence, peasants who are asked about some road in their own well known country reply that it is “straight ahead and impossible to miss” even when the road may turn ten times, right and left.

Human estimates are reliable only when tested and reviewed at each instant; complicated deductions are so only when deduction after deduction has been tested, each in itself. Lawyers must, therefore, inevitably follow the rule of requiring explication of each step in an inference—such a requirement will at least narrow the limits of error.

The task would be much easier if we were fortunate enough to be able to help ourselves with experiments. As Bernard[133] says, “There is an absolute determinism in the existential conditions of natural phenomena, as much in living as in non-living bodies. If the condition of any phenomenon is recognized and fulfilled the phenomenon must occur whenever the experimenter desires it.” But such determination can be made by lawyers in rare cases only, and to-day the criminalist who can test experimentally the generally asserted circumstance attested by witnesses, accused, or experts, is a rarissima avis. In most cases we have to depend on our experience, which frequently leaves us in difficulties if we fail thoroughly to test it. Even the general law of causation, that every effect has its cause, is formulated, as Hume points out, only as a matter of habit. Hume’s important discovery that we do not observe causality in the external world, demonstrates only the difficulty of the interpretation of causality. The weakness of his doctrine lies in his assertion that the knowledge of causality may be obtained through habit because we perceive the connection of similars, and the understanding, through habit, deduces the appearance of the one from that of the other. These assertions of the great thinker are certainly correct, but he did not know how to ground them. Hume teaches the following doctrine:

The proposition that causes and effects are recognized, not by the understanding but because of experience, will be readily granted if we think of such things as we may recollect we were once altogether unacquainted with. Suppose we give a man who has no knowledge of physics two smooth marble plates. He will never discover that when laid one upon the other they are hard to separate. Here it is easily observed that such properties can be discovered only through experience. Nobody, again, has the desire to deceive himself into believing that the force of burning powder or the attraction of a magnet could have been discovered a priori. But this truth does not seem to have the same validity with regard to such processes as we observed almost since breath began. With regard to them, it is supposed that the understanding, by its own activity, without the help of experience can discover causal connections. It is supposed that anybody who is suddenly sent into the world will be able at once to deduce that a billiard ball will pass its motion on to another by a push.

But that this is impossible to derive a priori is shown through the fact that elasticity is not an externally recognizable quality, so that we may indeed say that perhaps no effect can be recognized unless it is experienced at least once. It can not be deduced a priori that contact with water makes one wet, or that an object responds to gravity when held in the hand, or that it is painful to keep a finger in the fire. These facts have first to be experienced either by ourselves or some other person. Every cause, Hume argues therefore, is different from its effect and hence can not be found in the latter, and every discovery or representation of it a priori must remain voluntary. All that the understanding can do is to simplify the fundamental causes of natural phenomena and to deduce the individual effects from a few general sources, and that, indeed, only with the aid of analogy, experience, and observation.

But then, what is meant by trusting the inference of another person, and what in the other person’s narrative is free from inference? Such trust means, to be convinced that the other has made the correct analogy, has made the right use of experience, and has observed events without prejudice. That is a great deal to presuppose, and whoever takes the trouble of examining however simple and short a statement of a witness with regard to analogy, experience, and observation, must finally perceive with fear how blindly the witness has been trusted. Whoever believes in knowledge a priori will have an easy job: “The man has perceived it with his mind and reproduced it therewith; no objection may be raised to the soundness of his understanding; ergo, everything may be relied upon just as he has testified to it.” But he who believes in the more uncomfortable, but at least more conscientious, skeptical doctrine, has, at the minimum, some fair reason for believing himself able to trust the intelligence of a witness. Yet he neither is spared the task of testing the correctness of the witness’s analogy, experience and observation.

Apriorism and skepticism define the great difference in the attitude toward the witness. Both skeptic and apriorist have to test the desire of the witness to lie, but only the skeptic needs to test the witness’s ability to tell the truth and his possession of sufficient understanding to reproduce correctly; to examine closely his innumerable inferences from analogy, experience and observation. That only the skeptic can be right everybody knows who has at all noticed how various people differ in regard to analogies, how very different the experiences of a single man are, both in their observation and interpretation. To distinguish these differences clearly is the main task of our investigation.

There are two conditions to consider. One is the strict difference between what is causally related and its accidental concomitants,—a difference with regard to which experience is so often misleading, for two phenomena may occur together at the same time without being causally connected. When a man is ninety years old and has observed, every week in his life, that in his part of the country there is invariably a rainfall every Tuesday, this observation is richly and often tested, yet nobody will get the notion of causally connecting Tuesday and rain—but only because such connection would be regarded as generally foolish. If the thing, however, may be attributed to coincidence with a little more difficulty, then it becomes easier to suppose a causal connection; e.g., as when it rains on All-souls day, or at the new moon. If the accidental nature of the connection is still less obvious, the observation becomes a much-trusted and energetically defended meteorological law. This happens in all possible fields, and not only our witnesses but we ourselves often find it very difficult to distinguish between causation and accident. The only useful rule to follow is to presuppose accident wherever it is not indubitably and from the first excluded, and carefully to examine the problem for whatever causal connection it may possibly reveal. “Whatever is united in any perception must be united according to a general rule, but a great deal more may be present without having any causal relation.”

The second important condition was mentioned by Schopenhauer:[134] “As soon as we have assigned causal force to any great influence and thereby recognized that it is efficacious, then its intensification in the face of any resistance according to the intensity of the resistance will produce finally the appropriate effect. Whoever cannot be bribed by ten dollars, but vacillates, will be bribed by twenty-five or fifty.”

This simple example may be generalized into a golden rule for lawyers and requires them to test the effect of any force on the accused at an earlier time in the latter’s life or in other cases,—i.e., the early life of the latter can never be studied with sufficient care. This study is of especial importance when the question is one of determining the culpability of the accused with regard to a certain crime. We have then to ask whether he had the motive in question, or whether the crime could have been of interest to him. In this investigation the problem of the necessary intensity of the influence in question need not, for the time, be considered; only its presence needs to be determined. That it may have disappeared without any demonstrable special reason is not supposable, for inclinations, qualities, and passions are rarely lost; they need not become obvious so long as opportunity and stimulus are absent, and they may be in some degree suppressed, but they manifest themselves as soon as—Schopenhauer’s twenty-five or fifty dollars appear. The problem is most difficult when it requires the conversion of certain related properties, e.g., when the problem is one of suspecting a person of murderous inclination, and all that can be shown in his past life is the maltreatment of animals. Or again, when cruelty has to be shown and all that is established is great sensuality. Or when there is no doubt about cruelty and the problem is one of supposing intense avarice. These questions of conversion are not especially difficult, but when it must be explained to what such qualities as very exquisite egoism, declared envy, abnormal desire for honor, exaggerated conceit, and great idleness may lead to, the problem requires great caution and intensive study.

Section 25. (c) Skepticism.

Hume’s skepticism is directly connected with the subject of the preceding chapter, but wants still a few words for itself. Though it is not the lawyer’s problem to take an attitude with regard to philosophical skepticism, his work becomes essentially easier through the study of Hume’s doctrines.

According to these, all we know and infer, in so far as it is unmathematical, results from experience, and our conviction of it and our reasoning about it, means by which we pass the bounds of sense-perception, depend on sensation, memory and inference from causation. Our knowledge of the relation of cause and effect results also from experience, and the doctrine, applied to the work of the criminalist, may be formulated as follows: “Whatever we take as true is not an intellectual deduction, but an empirical proposition.” In other words, our presuppositions and inferential knowledge depend only upon those innumerable repetitions of events from which we postulate that the event recurred in the place in question. This sets us the problem of determining whether the similar cases with which we compare the present one really are similar and if they are known in sufficiently large numbers to exclude everything else.

Consider a simple example. Suppose somebody who had traveled all through Europe, but had never seen or heard of a negro, thought about the pigmentation of human beings: neither all his thinking nor the assistance of all possible scientific means can lead him to the conclusion that there are also black people—that fact he can only discover, not think out. If he depends only on experience, he must conclude from the millions of examples he has observed that all human beings are white. His mistake consists in the fact that the immense number of people he has seen belong to the inhabitants of a single zone, and that he has failed to observe the inhabitants of other regions.

In our own cases we need no examples, for I know of no inference which was not made in the following fashion: “The situation was so in a hundred cases, it must be so in this case.” We rarely ask whether we know enough examples, whether they were the correct ones, and whether they were exhaustive. It will be no mistake to assert that we lawyers do this more or less consciously on the supposition that we have an immense collection of suggestive a priori inferences which the human understanding has brought together for thousands of years, and hence believe them to be indubitably certain. If we recognize that all these presuppositions are compounds of experience, and that every experience may finally show itself to be deceptive and false; if we recognize how the actual progress of human knowledge consists in the addition of one hundred new experiences to a thousand old ones, and if we recognize that many of the new ones contradict the old ones: if we recognize the consequence that there is no reason for the mathematical deduction from the first to the hundred-and-first case, we shall make fewer mistakes and do less harm. In this regard, Hume[135] is very illuminative.

According to Masaryk,[136] the fundamental doctrine of Humian skepticism is as follows: “If I have had one and the same experience ever so often, i.e., if I have seen the sun go up 100 times, I expect to see it go up the 101st time the next day, but I have no guarantee, no certainty, no evidence for this belief. Experience looks only to the past, not to the future. How can I then discover the 101st sunrise in the first 100 sunrises? Experience reveals in me the habit to expect similar effects from similar circumstances, but the intellect has no share in this expectation.”

All the sciences based on experience are uncertain and without logical foundation, even though their results, as a whole and in the mass, are predictable. Only mathematics offers certainty and evidence. Therefore, according to Hume, sciences based on experience are unsafe because the recognition of causal connection depends on the facts of experience and we can attain to certain knowledge of the facts of experience only on the ground of the evident relation of cause and effect.

This view was first opposed by Reid, who tried to demonstrate that we have a clear notion of necessary connection. He grants that this notion is not directly attained either from external or internal experience, but asserts its clearness and certainty in spite of that fact. Our mind has the power to make its own concepts and one such concept is that of necessary connection. Kant goes further and says that Hume failed to recognize the full consequences of his own analysis, for the notion of causality is not the only one which the understanding uses to represent a priori the connection of objects. And hence, Kant defines psychologically and logically a whole system of similar concepts. His “Critique of Pure Reason” is intended historically and logically as the refutation of Hume’s skepticism. It aims to show that not only metaphysics and natural science have for their basis “synthetic judgments a priori,” but that mathematics also rests on the same foundation.

Be that as it may, our task is to discover the application of Hume’s skepticism to our own problems in some clear example. Let us suppose that there are a dozen instances of people who grew to be from 120 to 140 years old. These instances occur among countless millions of cases in which such an age was not reached. If this small proportion is recognized, it justifies the postulate that nobody on earth may attain to 150 years. But now it is known that the Englishman Thomas Parr got to be 152 years old, and his countryman Jenkins was shown, according to the indubitable proofs of the Royal Society, to be 157 years old at least (according to his portrait in a copper etching he was 169 years old). Yet as this is the most that has been scientifically proved I am justified in saying that nobody can grow to be 200 years old. Nevertheless because there are people who have attained the age of 180 to 190 years, nobody would care to assert that it is absolutely impossible to grow so old. The names and histories of these people are recorded and their existence removes the great reason against this possibility.

We have to deal, then, only with greater or lesser possibilities and agree with the Humian idea that under similar conditions frequency of occurrence implies repetition in the next instance. Contrary evidence may be derived from several so-called phenomena of alternation. E. g., it is a well known fact that a number in the so-called Little Lottery, which has not been drawn for a long time, is sure finally to be drawn. If among 90 numbers the number 27 has not turned up for a long time its appearance becomes more probable with every successive drawing. All the so-called mathematical combinations of players depend on this experience, which, generalized, might be held to read: the oftener any event occurs (as the failure of the number 27 to be drawn) the less is the probability of its recurrence (i.e., it becomes more probable that 27 will be drawn)—and this seems the contrary of Hume’s proposition.

It may at first be said that the example ought to be put in a different form, i.e., as follows: If I know that a bag contains marbles, the color of which I do not know, and if I draw them one by one and always find the marble I have drawn to be white, the probability that the bag contains only white ones grows with every new drawing that brings a white marble to light. If the bag contains 100 marbles and 99 have been drawn out, nobody would suppose that the last one would be red—for the repetition of any event increases the probability of its occurrence.

This formulation proves nothing, inasmuch as a different example does not contradict the one it is intended to substitute. The explanation is rather as follows: In the first case there is involved the norm of equal possibilities, and if we apply the Humian principle of increase of probability through repetition, we find it effective in explaining the example. We have known until now always that the numbers in the Little Lottery are drawn equally, and with approximate regularity,—i.e., none of the single numbers is drawn for a disproportionately long time. And as this fact is invariable, we may suppose that every individual number would appear with comparative regularity. But this explanation is in accord with Hume’s doctrine.

The doctrine clarifies even astonishing statistical miracles. We know, e.g., that every year there come together in a certain region a large number of suicides, fractures of arms and legs, assaults, unaddressed letters, etc. When, now, we discover that the number of suicides in a certain semester is significantly less than the number in the same semester of another year, we will postulate that in the next half-year a comparatively larger number of suicides will take place so that the number for the whole year will become approximately equal. Suppose we say: “There were in the months of January, February, March, April, May and June an average of x cases. Because we have observed the average to happen six times, we conclude that it will not happen in the other months but that instead, x+y cases will occur in those months, since otherwise the average annual count will not be attained.” This would be a mistaken abstraction of the principle of equal distribution from the general Humian law, for the Humian law applied to this case indicates: “For a long series of years we have observed that in this region there occur annually so and so many suicides; we conclude therefore that in this year also there will occur a similar number of suicides.”

The principle of equal distribution presents itself therefore as a subordinate rule which must not be separated from the principal law. It is, indeed, valid for the simplest events. When I resolve to walk in x street, which I know well, and when I recall whether to-day is Sunday or a week day, what time it is and what the weather is like, I know quite accurately how the street will look with regard to the people that may be met there, although a large number of these people have chosen the time accidentally and might as well have passed through another street. If, for once, there were more people in the street, I should immediately ask myself what unusual event had taken place.

One of my cousins who had a good deal of free time to dispose of, spent it for several months, with the assistance of his comrade, in counting the number of horses that passed daily, in the course of two hours, by a café they frequented. The conscientious and controlled count indicated that every day there came one bay horse to every four. If then, on any given day, an incommensurably large number of brown, black, and tawny horses came in the course of the first hour, the counters were forced to infer that in the next 60 minutes horses of a different color must come and that a greater number of bays must appear in order to restore the disturbed equilibrium. Such an inference is not contradictory to the Humian proposition. At the end of a series of examinations the counters were compelled to say, “Through so many days we have counted one bay to every four horses; we must therefore suppose that a similar relationship will be maintained the next day.”

So, the lawyer, too, must suppose, although we lawyers have nothing to do with figures, that he knows nothing a priori, and must construct his inferences entirely from experience. And hence we must agree that our premises for such inferences are uncertain, and often subject to revision, and often likely, in their application to new facts, to lead to serious mistakes, particularly if the number of experiences from which the next moment is deduced, are too few; or if an unknown, but very important condition is omitted.

These facts must carefully be kept in mind with reference to the testimony of experts. Without showing ourselves suspicious, or desirous of confusing the professional in his own work, we must consider that the progress of knowledge consists in the collection of instances, and anything that might have been normal in 100 cases, need not in any sense be so when 1000 cases are in question. Yesterday the norm may have been subject to no exception; to-day exceptions are noted; and to-morrow the exception has become the rule.

Hence, rules which have no exceptions grow progressively rarer, and wherever a single exception is discovered the rule can no longer be held as normative. Thus, before New Holland was discovered, all swans were supposed to be white, all mammals incapable of laying eggs; now we know that there are black swans and that the duck-bill lays eggs. Who would have dared to assert before the discovery of the X-ray that light can penetrate wood, and who, especially, has dared to make generalizations with regard to the great inventions of our time which were not afterwards contradicted by the facts? It may be that the time is not too far away in which great, tenable and unexceptionable principles may be posited, but the present tendency is to beware of generalizations, even so far as to regard it a sign of scientific insight when the composition of generally valid propositions is made with great caution. In this regard the great physicians of our time are excellent examples. They hold: “whether the phenomenon A is caused by B we do not know, but nobody has ever yet seen a case of A in which the precedence of B could not be demonstrated.” Our experts should take the same attitude in most cases. It might be more uncomfortable for us, but certainly will be safer; for if they do not take that attitude we are in duty bound to presuppose in our conclusions that they have taken it. Only in this wise, by protecting ourselves against apparently exceptionless general rules, can our work be safely carried on.

This becomes especially our duty where, believing ourselves to have discovered some generally valid rule, we are compelled to draw conclusions without the assistance of experts. How often have we depended upon our understanding and our “correct” a priori method of inference, where that was only experience,—and such poor experience! We lawyers have not yet brought our science so far as to be able to make use of the experience of our comrades with material they have reviewed and defined in writing. We have bothered a great deal about the exposition of some legal difficulty, the definition of some judicial concept, but we have received little instruction or tradition concerning mankind and its passions. Hence, each one has to depend on his own experience, and that is supposed to be considerable if it has a score of years to its back, and is somewhat supplemented by the experience, of others. In this regard there are no indubitable rules; everybody must tell himself, “I have perhaps never experienced this fact, but it may be that a thousand other people have seen it, and seen it in a thousand different ways. How then, and whence, my right to exclude every exception?”

We must never forget that every rule is shattered whenever any single element of the situation is unknown, and that happens very easily and frequently. Suppose that I did not have full knowledge of the nature of water, and walked on terra firma to the edge of some quiet, calm pool. When now I presume: water has a body, it has a definite density, it has consistency, weight, etc., I will also presume that I may go on walking over its surface just as over the surface of the earth,—and that, simply because I am ignorant of its fluidity and its specific gravity. Liebman[137] summarizes the situation as follows. The causal nexus, the existential and objective relation between lightning and thunder, the firing of powder and the explosion, are altogether different from the logical nexus, i.e. the mere conceptual connection between antecedent and consequent in deduction. This constitutes the well known kernel of Humian skepticism. We must keep in mind clearly that we never can know with certainty whether we are in possession of all the determining factors of a phenomenon, and hence we must adhere to the only unexceptionable rule: Be careful about making rules that admit of no exceptions. There is still another objection to discuss, i.e. the mathematical exception to Humian skepticism. It might be held that inasmuch as the science of justice is closely related in many ways to mathematics, it may permit of propositions a priori. Leibnitz already had said, “The mathematicians count with numbers, the lawyers with ideas,—fundamentally both do the same thing.” If the relationship were really so close, general skepticism about phenomenal sciences could not be applied to the legal disciplines. But we nowadays deal not with concepts merely, and in spite of all obstruction, Leibnitz’s time has passed and the realities of our profession, indeed its most important object, the human being itself, constitute an integrating part of our studies. And the question may be still further raised whether mathematics is really so exempt from skepticism. The work of Gauss, Lobatschewski, Bolyai, Lambert, would make the answer negative.

Let us, for once, consider what significance mathematical postulates have. When Pythagoras discovered his proposition in such a way that he first drew a right-angled triangle and then built a square on each of the sides, and finally measured the area of each and compared them, he must at first have got the notion that that also might be merely accidental. If he had made the construction 10 or 100 times with various triangles and these had resulted always identically, only then might he have been justified in saying that he had apparently discovered a theorem. But then his process was just as thoroughly experiential as that of a scientist who says that a bird has never yet been observed to give birth to living young, and that hence all birds lay eggs.

But Pythagoras did not proceed in this experiential manner in the discovery of his theorem. He constructed and he counted, and when he did that he acted on postulates: “If this is a right-angled triangle and if that be a square, so,”—and this is just what is done in every science. The general propositions are, “If the relations remain the same as formerly the moon must rise to-morrow at such and such a time.” “If this step in a deduction is not false, if it is well grounded at this point, if it really refers to x, it follows....” In his procedures the criminalist does exactly the same thing. What he must be skeptical about is the postulates from which he starts.

Section 26. (d) The Empirical Method in the Study of Cases.

Properly to bound our discussion of Humian skepticism, a few words have to be said concerning the empirical method of the sciences. We will call those laws purely empirical which, in the study of nature, yield regularities that are demonstrated by observation and experiment, but upon which little or no reliance is placed with regard to cases which differ considerably from the observed. The latter is done because no reason is seen for the existence of such laws. The empirical rule is, therefore, no final law, but is capable of explaining, especially when true, e.g., the succession of a certain condition of weather from certain meteorological signs, the improvement of species through crossing, the fact that some alloys are harder than their components, and so on. Or, to choose examples from our own field, jurisprudence may assert as empirical law that a murderer is a criminal who has gone unpunished for his earlier crimes; that all gamblers show such significant resemblances; that the criminal who has soiled his hands with blood in some violent crime was accustomed to wipe them on the underside of a table; that the slyest person generally perpetrates some gross stupidity after committing a serious crime, and so renders discovery simpler; that lust and cruelty have a certain relation; that superstition plays a great rôle in crime, etc.

It is of exceeding importance to establish such purely empiric laws in our science, which has done little with such matters because, owing to scanty research into most of them, we need these laws. We know approximately that this and that have come to light so and so often, but we have not reduced to order and studied systematically the cases before us, and we dare not call this knowledge natural law because we have subjected it to no inductive procedure. “The reference of any fact discovered by experience to general laws or rules we call induction. It embraces both observation and deduction.” Again, it may be defined as “the generalization or universalization of our experiences; and inference that a phenomenon occurring x times will invariably occur when the essential circumstances remain identical. The earliest investigators started with the simplest inductions,—that fire burns, that water flows downward,—so that new, simple truths were continually discovered. This is the type of scientific induction and it requires further, the addition of certainty and accuracy.”[138]

The foregoing might have been written expressly for us lawyers, but we have to bear in mind that we have not proceeded in our own generalizations beyond “fire burns, water flows downward.” And such propositions we have only derived from other disciplines. Those derived from our own are very few indeed, and to get more we have very far to go. Moreover, the laws of experience are in no way so certain as they are supposed to be, even when mathematically conceived. The empirical law is established that the sum of the three angles of a triangle is equal to two right angles. And yet nobody, ever since the science of surveying has been invented, has succeeded in discovering 180 degrees in any triangle. Now then, when even such things, supposed ever since our youth to be valid, are not at all true, or true theoretically only, how much more careful must we be in making inferences from much less certain rules, even though we have succeeded in using them before in many analogous cases? The activity of a criminalist is of far too short duration to permit him to experience any more than a very small portion of the possibilities of life, and suggestions from foreign sources are very rare. The situation is different in other disciplines. “Our experience,” says James Sully,[139] “enables us to express a number of additional convictions. We can predict political changes and scientific developments, and can conceive of the geographical conditions at the north pole.” Other disciplines are justified to assert such additional propositions, but is ours? A man may have dealt for years with thieves and swindlers, but is he justified in deducing from the inductions made in his experience, the situation of the first murderer he deals with? Is he right in translating things learned by dealing with educated people to cases where only peasants appear? In all these cases what is needed in making deductions is great caution and continual reminder to be very careful, for our work here still lacks the proper material. In addition we have to bear in mind that induction is intimately related to analogy. According to Lipps[140] the ground of one is the ground of the other; they both rest on the same foundation. “If I am still in doubt whether the fact on which a moment ago I depended as the sufficient condition for a judgment may still be so regarded, the induction is uncertain. It is unjustified when I take for sufficiently valid something that as a matter of fact ought not to be so taken.” If we bear in mind how much we are warned against the use of analogy, how it is expressly excluded in the application of certain criminal laws, and how dangerous the use of every analogy is, we must be convinced that the use for our cases of both induction and analogy, is always menace. We have at the same time to bear in mind how much use we actually make of both; even our general rules—e.g., concerning false testimony,—bias, revertibility, special inclinations, etc.—and our doctrines concerning the composition and indirection of testimony, even our rules concerning the value of witnesses and confessions, all these depend upon induction and analogy. We pass by their use in every trial from case to case. A means so frequently and universally used must, however, be altogether reliable, or be handled with the greatest care. As it is not the first it must be handled in the second way.

We have yet to indicate the various ways in which induction may be used. Fick has already called attention to the astounding question concluding Mill’s system of logic: Why, in many cases, is a single example sufficient to complete induction, while in other cases myriads of unanimous instances admitting of no single known or suspected exception, make only a small step toward the establishment of a generally valid judgment?

This question is of enormous significance in criminal cases because it is not easy to determine in any particular trial whether we have to deal with a situation of the first sort where a single example is evidential, or a situation of the second sort where a great many examples fail to be evidential. On this difficulty great mistakes depend, particularly mistakes of substitution of the first for the second. We are satisfied in such cases with a few examples and suppose ourselves to have proved the case although nothing whatever has been established.

We must see first of all if it is of any use to refer the difficulty of the matter to the form in which the question is put, and to say: The difficulty results from the question itself. If it be asked, “Are any of the thousand marbles in the bag white marbles?” the question is determined by the first handful, if the latter brings to light a single white marble. If, however, the problem is phrased so: Does the bag contain white marbles only? then, although 999 marbles might already have been drawn from the receptacle, it can not be determined that the last marble of the 1000 is white. In the same way, if people assert that the form of the question determines the answer, it does not follow that the form of the question is itself determined or distinguished inasmuch as the object belongs to the first or the second of the above named categories.

A safe method of distinction consists in calling the first form of the question positive and the second negative. The positive refers to a single unit; the negative to a boundless unit. If then I ask: Are there any white marbles whatever in the bag? the answer is rendered affirmative by the discovery of a single white marble. But if the question is phrased: Are there only white marbles in the bag? merely its form is positive but its intent is negative. To conform the manner of the question to its intent, it would be necessary to ask: Are there no other colors than white among the marbles in the bag? And inasmuch as the negative under given circumstances is in many ways boundless, the question admits of no answer until the last marble has been brought to light. If the total number of marbles is unlimited the question can receive no complete inductive answer in mathematical form; it can be solved only approximately. So again, if one asks: Are there any purely blue birds? the answer is affirmative as soon as a single completely blue bird is brought to light. But if the question is: Do not also striped birds exist? no answer is possible until the very last bird on earth is exhibited. In that way only could the possibility be excluded that not one of the terrestrial fowls is striped. As a matter of fact we are satisfied with a much less complete induction. So we say: Almost the whole earth has been covered by naturalists and not one of them reports having observed a striped bird; hence there would be none such even in the unexplored parts of the earth. This is an inductive inference and its justification is quite another question.

The above mentioned distinction may be made still clearer if instead of looking back to the form of the question, we study only the answer. We have then to say that positive statements are justified by the existence of a single instance, negative assertions only by the complete enumeration of all possible instances and never at all if the instances be boundless. That the negative proof always requires a series of demonstrations is well known; the one thing which may be firmly believed is the fact that the problem, whether a single example is sufficient, or a million are insufficient, is only a form of the problem of affirmative and negative assertions.

So then, if I ask: Has A ever stolen anything? it is enough to record one judgment against him, or to bring one witness on the matter in order to establish that A committed theft at least once in his life. If, however, it is to be proved that the man has never committed a theft, his whole life must be reviewed point by point, and it must be shown that at no instant of it did he commit larceny. In such cases we are content with much less. We say first of all: We will not inquire whether the man has never stolen. We will see merely whether he was never punished for theft. But here, too, we must beware and not commit ourselves to inquiring of all the authorities in the world, but only of a single authority, who, we assume, ought to know whether A was punished or not. If we go still further, we say that inasmuch as we have not heard from any authorities that the man was ever punished for stealing, we suppose that the man was never punished on that ground; and inasmuch as we have not examined anybody who had seen A steal, we preferably suppose that he has never stolen. This is what we call satisfactory evidence, and with the poor means at our disposal it must suffice.

In most cases we have to deal with mixed evidence, and frequently it has become habitual to change the problem to be solved according to our convenience, or at least to set aside some one thing. Suppose that the issue deals with a discovered, well-retained footprint of a man. We then suspect somebody and compare the sole of his shoe with the impression. They fit in length and width, in the number of nails and in all the other possible indices, and we therefore assert: It is the footprint of the suspect, for “whose footprint?” is the problem we are troubling ourselves to solve. In truth we have only shown that the particular relations, in the matter of length, breadth, number of nails, etc., agree, and hence we regard the positive part of the evidence as sufficient and neglect the whole troublesome negative part, which might establish the fact that at the time and in the region in question, nobody was or could be whose foot could accurately fit that particular footprint. Therefore we have not proved but have only calculated the probability that at the time there might possibly not have been another person with a shoe of similar length, breadth and number of nails. The probability becomes naturally less as fewer details come to hand. The difficulty lies in finding where such probability, which stands for at least an assumption, must no longer be considered. Suppose, now, that neither shoe-nails nor patches, nor other clear clews can be proved and only length and width agree. If the agreement of the clews were really a substantiation of the proof by evidence, it would have to suffice as positive evidence; but as has been explained, the thing proved is not the point at issue, but another point.

The negative portion of the evidence will naturally be developed with less accuracy. The proof is limited to the assertion that such shoes as were indicated in the evidence were very rarely or never worn in that region, also that no native could have been present, that the form of the nails allowed inference of somebody from foreign regions, one of which might be the home of the suspect, etc. Such an examination shows that what we call evidence is only probability or possibility.

Another form which seems to contradict the assertion that negative propositions are infinite is positive evidence in the shape of negation. If we give an expert a stain to examine and ask him whether it is a blood stain, and he tells us: “It is not a blood stain,” then this single scientifically established assertion proves that we do not have to deal with blood, and hence “negative” proof seems brought in a single instance. But as a matter of fact we deal here with an actually positive proof, for the expert has given us the deduced proposition, not the essential assertion. He has found the stain to be a rust stain or a tobacco stain, and hence he may assert and deduce that it is not blood. Even were he a skeptic, he would say, “We have not yet seen the blood of a mammal in which the characteristic signs for recognition were not present, and we have never yet recognized a body without the blood pertaining to it, and hence we may say, we are not dealing with blood because all of us found the characteristics of the stain to be what we have been until now accustomed to call the characteristics of rust stain.”

We have still to touch upon the difference between logical connection and experience. If I say, “This mineral tastes salty, therefore it is soluble in water,” the inference depends upon logical relationships, for my intent is: “If I perceive a salty taste, it has to be brought to the nerves of taste, which can be done only by the combination of the mineral with the saliva, hence by its solution in the saliva. But if it is soluble in saliva it must also be soluble in water.” If I say on the other hand, “This mineral tastes salty, has a hardness of 2, a specific gravity of 2.2, and consequently it crystallizes hexagonally,”—this statement depends on experience, for what I really say is: “I know first of all, that a mineral which has the qualities mentioned must be rock salt; for at the least, we know of no mineral which has these qualities and is not rock salt, and which in the second place crystallizes hexagonally as rock salt does,—a way which, at least, we find rock salt never to have missed.” If we examine the matter still more closely we become convinced that in the first case only the formal and logical side, in the second the experiential aspect predominates. The premises of both cases are purely matters of experience and the formal question of inference is a matter of logic. Only,—at one time the first question, at another the second comes more obviously into the foreground. Although this matter appears self-evident it is not indifferent. It is well known that whenever we are powerfully influenced by one thing, things of little intensity are either not experienced at all or only to a very small degree, and are therefore neglected. This is a fact which may indeed be shown mathematically, for infinity plus one equals infinity. When, therefore, we undergo great pain or great joy, any accompanying insignificant pain or any pleasure will be barely felt, just as the horses who drag a very heavy wagon will not notice whether the driver walking beside them adds his coat to the load (cf. Weber’s law). Hence, when we criminalists study a difficult case with regard to the question of proof, there are two things to do in order to test the premises for correctness according to the standards of our other experiences, and to draw logically correct inferences from these premises. If it happens that there are especial difficulties in one direction while by some chance those in the other are easily removed, it becomes surprising how often the latter are entirely ignored. And hence, the adjustment of inferences is naturally false even when the great difficulties of the first type are removed correctly. Therefore, if the establishment of a fact costs a good deal of pains and means the expenditure of much time, the business of logical connection appears so comparatively easy that it is made swiftly and—wrongly.

Mistakes become, at least according to my experience, still more frequent when the difficulty is logical and not empirical. As a matter of honesty, let me say that we criminalists are not trained logicians, however necessary it is that we shall be such, and most of us are satisfied with the barren remainder of what we learned long ago in the Gymnasium and have since forgotten. The difficulties which occur in the more important logical tasks are intelligible when compared with the lesser difficulties; and when one of these larger problems is by good fortune rightly solved, the effort and the work required by the solution make it easy to forget asking whether the premises are correct; they are assumed as self-evident. Hence, in the review of the basis for judgment, it is often discovered that the logical task has been performed with care, with the expenditure of much time, etc., only to be based upon some apparently unessential presupposition which contradicts all experience and is hence materially incorrect. Consequence,—the inference is wrong since the premise was wrong, and the whole work has gone for nothing. Such occurrences convince one that no judge would have been guilty of them if the few difficulties concerning the fact in question were not, because treated in the light of the effort required by the logical work, quite neglected. Nor does this occur unconsciously, or as a consequence of a sort of lapse of memory concerning the meaning or the importance of an empirical problem, it also happens at least half consciously by way of a characteristic psychic process which everybody may identify in his own experience: i.e., the idea occurs, in some degree subconsciously, that the overgreatness of the work done in one direction ought to be corrected by the inadequacy of the work done in the other direction. And this happens in lawyer’s work often, and being frequently justifiable, becomes habitual. If I, for example, have examined ten unanimous witnesses concerning the same event and have completely demonstrated the status of the case, I ought, in examining the last two witnesses, who are perhaps no longer needed but have been summoned and appear, certainly to proceed in a rapid manner. This justifiable neglect is then half unconsciously transferred to other procedures where there is possible no equalization of the hypertrophy of work in one direction with the dwarfing of it in another, and where the mistake causes the result to be wrong. However I may have been bothered by the multiplication of ten groups of factors and whatever accuracy I may have applied to a task can not permit me to relax my attention in the addition of the individual results. If I do I am likely to commit an error and the error renders all the previous labor worthless.

Indeed, it may be asserted that all logic is futile where the premises or a single premise may be wrong. I expect, in truth, that the procedures here described will be doubted to be even possible, but doubters are recommended to examine a few cases for the presence of this sort of thing.

Section 27. (e) Analogy.

Analogy is the least negligible of all methods of induction because it rests at bottom on the postulate that one thing which has a number of qualities in common with another will agree with that other in one or more additional qualities. In cases of analogy, identity is never asserted; indeed, it is excluded, while a certain parallelism and agreement in specific points are assumed, i.e., introduced tacitly as a mutatis mutandis. Consider Lipps’s examples. He calls analogy the transfer of judgment or the transition from similar to similar, and he adds that the value of such a process is very variable. If I have perceived x times that flowers of a certain color have perfume, I am inclined to expect perfume from flowers of the same color in x+1 cases. If I have observed x times that clouds of a certain structure are followed by rain I shall expect rain in the x+1st case. The first analogy is worthless because there is no relation between color and perfume; the second is of great value because such a relation does exist between rain and clouds.

Simply stated, the difference between these two examples does not consist in the existence of a relationship in the one case and the absence of a relationship in the other; it consists in the fact that in the case of the flowers the relationship occurs now and then but is not permanently knowable. It is possible that there is a natural law controlling the relation between color and odor, and if that law were known there would be no question of accident or of analogy, but of law. Our ignorance of such a law, in spite of the multiplicity of instances, lies in the fact that we are concerned only with the converse relationships and not with the common cause of perfume and color. Suppose I see on the street a large number of people with winter over-coats and a large number of people with skates in their hands, I would hardly ask whether the coats are conditioned or brought out by the skates or the skates by the coats. If I do not conclude that the cold weather is the condition both of the need of over-coats and the utility of skates, I will suppose that there is some unintelligible reflexive relation between over-coats and skates. If I observe that on a certain day every week there regularly appear many well-dressed people and no workingmen on the street, if I am ignorant of the fact that Sunday is the cause of the appearance of the one and the disappearance of the other, I shall try in vain to find out how it happens that the working people are crowded out by the well-dressed ones or conversely.

The danger of analogy lies in the fact that we prefer naturally to depend on something already known, and that the preference is the greater in proportion to our feeling of the strangeness and ominousness of the particular intellectual or natural regions in which we find ourselves. I have already once demonstrated[141] how disquieting it is to notice, during the examination of the jury, that the jurymen who ask questions try to find some relation to their own trades even though this requires great effort, and seek to bring the case they are asking about under the light of their particular profession. So, however irrelevant the statement of a witness may be, the merchant juryman will use it to explain Saldo-Conti, the carpenter juryman to explain carpentry, the agriculturist to notice the farming of cattle, and then having set the problem in his own field construct the most daring analogies, for use in determining the guilt of the accused. And we lawyers are no better. The more difficult and newer a case is the more are we inclined to seek analogies. We want supports, for we do not find firm natural laws, and in our fear we reach out after analogies, not of course in law, because that is not permitted, but certainly in matters of fact. Witness X has given difficult testimony in a certain case. We seek an analogy in witness Y of an older case, and we observe the present issue thus analogically, without the least justification. We have never yet seen drops of blood on colored carpets, yet we believe in applying our experience of blood stains on clothes and boots analogically. We have before us a perfectly novel deed rising from perverted sexual impulse—and we presuppose that the accused is to be treated altogether analogously to another in a different case, although indeed the whole event was different.

Moreover the procedure, where the analogy is justified, is complex. “With insight,” says Trendelenburg, “did the ancients regard analogy as important. The power of analogy lies in the construction and induction of a general term which binds the subconcept with regard to which a conclusion is desired, together with the individual object which is compared with the first, and which is to appear as a mediating concept but can not. This new general term is not, however, the highest concept among the three termini of the conclusion; it is the middle one and is nothing else than the terminus medius of the first figure.” This clear statement shows not only how circumstantial every conclusion from analogy is, but also how little it achieves. There is hardly any doubt of the well-known fact that science has much to thank analogy for, since analogy is the simplest and easiest means for progress in thought. If anything is established in any one direction but progress is desired in another, then the attempt is made to adapt what is known to the proximate unknown and to draw the possible inference by analogy. Thousands upon thousands of analogies have been attempted and have failed,—but no matter; one successful one became a hypothesis and finally an important natural law. In our work, however, the case is altogether different, for we are not concerned with the construction of hypotheses, we are concerned with the discovering of truth, or with the recognition that it cannot be discovered.

The only place where our problems permit of the use of analogy is in the making of so-called constructions, i.e., when we aim to clarify or to begin the explanation of a case which is at present unintelligible, by making some assumption. The construction then proceeds in analogy to some already well known earlier case. We say: “Suppose the case to have been so and so,” and then we begin to test the assumption by applying it to the material before us, eliminating and constructing progressively until we get a consistent result. There is no doubt that success is frequently attained in this way and that it is often the only way in which a work may be begun. At the same time, it must be recognized how dangerous this is, for in the eagerness of the work it is easy to forget that so far, one is working only according to analogy by means of an assumption still to be proved. This assumption is in such cases suddenly considered as something already proved and is counted as such with the consequence that the result must be false. If you add the variability in value of analogy, a variability not often immediately recognized, the case becomes still worse. We have never been on the moon, have therefore apparently no right to judge the conditions there—and still we know—only by way of analogy—that if we jumped into the air there we should fall back to the ground. But still further: we conclude again, by analogy, that there are intelligent beings on Mars; if, however, we were to say how these people might look, whether like us or like cubes or like threads, whether they are as large as bees or ten elephants, we should have to give up because we have not the slightest basis for analogy.

In the last analysis, analogy depends upon the recurrence of similar conditions. Therefore we tacitly assume when we judge by analogy that the similarity of conditions contains an equivalence of ultimately valid circumstance. The certainty of analogy is as great as the certainty of this postulate, and its right as great as the right of this postulate.

If, then, the postulate is little certain, we have gained nothing and reach out into the dark; if its certainty is great we no longer have an analogy, we have a natural law. Hence, Whately uses the term analogy as an expression for the similarity of relation, and in this regard the use of analogy for our real work has no special significance. Concerning so-called false analogies and their importance cf. J. Schiel’s Die Methode der induktiven Forschung (Braunschweig 1865).

Section 28. (f) Probability.

Inasmuch as the work of the criminal judge depends upon the proof of evidence, it is conceivable that the thing for him most important is that which has evidential character or force.[142] A sufficient definition of evidence or proof does not exist because no bounds have been set to the meaning of “Proved.” All disciplines furnish examples of the fact that things for a long time had probable validity, later indubitable validity; that again some things were considered proved and were later shown to be incorrect, and that many things at one time wobbly are in various places, and even among particular persons, supposed to be at the limits of probability and proof. Especially remarkable is the fact that the concept of the proved is very various in various sciences, and it would be absorbing to establish the difference between what is called proved and what only probable in a number of given examples by the mathematician, the physicist, the chemist, the physician, the naturalist, the philologist, the historian, the philosopher, the lawyer, the theologian, etc. But this is no task for us and nobody is called upon to determine who knows what “Proved” means. It is enough to observe that the differences are great and to understand why we criminalists have such various answers to the question: Is this proved or only probable? The varieties may be easily divided into groups according to the mathematical, philosophic, historical or naturalistic inclinations of the answerer. Indeed, if the individual is known, what he means by “proved” can be determined beforehand. Only those minds that have no especial information remain confused in this regard, both to others, and to themselves.

Sharply to define the notion of “proved” would require at least to establish its relation to usage and to say: What we desire leads us to an assumption, what is possible gives us probability, what appears certain, we call proved. In this regard the second is always, in some degree, the standard for the first (desires, e.g., cause us to act; one becomes predominant and is fixed as an assumption which later on becomes clothed with a certain amount of reliability by means of this fixation).

The first two fixations, the assumption and the probability, have in contrast to their position among other sciences only a heuristic interest to us criminalists. Even assumptions, when they become hypotheses, have in various disciplines a various value, and the greatest lucidity and the best work occur mainly in the quarrel about an acutely constructed hypothesis.

Probability has a similar position in the sciences. The scholar who has discovered a new thought, a new order, explanation or solution, etc., will find it indifferent whether he has made it only highly probable or certain. He is concerned only with the idea, and a scholar who is dealing with the idea for its own sake will perhaps prefer to bring it to a great probability rather than to indubitable certainty, for where conclusive proof is presented there is no longer much interest in further research, while probability permits and requires further study. But our aim is certainty and proof only, and even a high degree of probability is no better than untruth and can not count. In passing judgment and for the purpose of judgment a high degree of probability can have only corroborative weight, and then it is probability only when taken in itself, and proof when taken with regard to the thing it corroborates. If, for example, it is most probable that X was recognized at the place of a crime, and if at the same time his evidence of alibi has failed, his footmarks are corroborative; so are the stolen goods which have been seen in his possession, and something he had lost at the place of the crime which is recognized as his property, etc. In short, when all these indices are in themselves established only as highly probable, they give under certain circumstances, when taken together, complete certainty, because the coincidence of so many high probabilities must be declared impossible if X were not the criminal.

In all other cases, as we have already pointed out, assumption and probability have only a heuristic value for us lawyers. With the assumption, we must of course count; many cases can not be begun without the assistance of assumption. Every only half-confused case, the process of which is unknown, requires first of all and as early as possible the application of some assumption to its material. As soon as the account is inconsistent the assumption must be abandoned and a fresh one and yet again a fresh one assumed, until finally one holds its own and may be established as probable. It then remains the center of operation, until it becomes of itself a proof or, as we have explained, until so many high probabilities in various directions have been gathered, that, taken in their order, they serve evidentially. A very high degree of probability is sufficient in making complaints; but sentencing requires “certainty,” and in most cases the struggle between the prosecution and the defense, and the doubt of the judge, turns upon the question of probability as against proof.[143]

That probability is in this way and in a number of relations, of great value to the criminalist can not appear doubtful. Mittermaier defines its significance briefly: “Probability naturally can never lead to sentence. It is, however, important as a guide for the conduct of the examiner, as authorizing him to take certain measures; it shows how to attach certain legal processes in various directions.”

Suppose that we review the history of the development of the theory of probability. The first to have attempted a sharp distinction between demonstrable and probable knowledge was Locke. Leibnitz was the first to recognize the importance of the theory of probability for inductive logic. He was succeeded by the mathematician Bernoulli and the revolutionist Condorcet. The theory in its modern form was studied by Laplace, Quetelet, Herschel, von Kirchmann, J. von Kries, Venn, Cournot, Fick, von Bortkiewicz, etc. The concept that is called probability varies with different authorities. Locke[144] divides all fundamentals into demonstrative and probable. According to this classification it is probable that “all men are mortal,” and that “the sun will rise to-morrow.” But to be consistent with ordinary speech the fundamentals must be classified as evidence, certainties, and probabilities. By certainties I understand such fundamentals as are supported by experience and leave no room for doubt or consideration—everything else, especially as it permits of further proof, is more or less probable.

Laplace[145] spoke move definitely—“Probability depends in part on our ignorance, in part on our knowledge....

“The theory of probability consists in the reduction of doubts of the same class of a definite number of equally possible cases in such a way that we are equally undetermined with regard to their existence, and it further consists in the determination of the number of those cases which are favorable to the result the probability of which is sought. The relation of this number to the number of all possible cases is the measure of the probability. It is therefore a fraction the numerator of which is derived from the number of cases favorable to the result and the denominator from the number of all possible cases.” Laplace, therefore, with J. S. Mill, takes probability to be a low degree of certainty, while Venn[146] gives it an objective support like truth. The last view has a great deal of plausibility inasmuch as there is considerable doubt whether an appearance is to be taken as certain or as only probable. If this question is explained, the assertor of certainty has assumed some objective foundation which is indubitable at least subjectively. Fick represents the establishment of probability as a fraction as follows: “The probability of an incompletely expressed hypothetical judgment is a real fraction proved as a part of the whole universe of conditions upon which the realization of the required result necessarily depends.

“According to this it is hardly proper to speak of the probability of any result. Every individual event is either absolutely necessary or impossible. The probability is a quality which can pertain only to a hypothetical judgment.”[147]

That it is improper to speak of the probability of a result admits of no doubt, nor will anybody assert that the circumstance of to-morrow’s rain is in itself probable or improbable—the form of expression is only a matter of usage. It is, however, necessary to distinguish between conditioned and unconditioned probability. If I to-day consider the conditions which are attached to the ensuing change of weather, if I study the temperature, the barometer, the cloud formation, the amount of sunlight, etc., as conditions which are related to to-morrow’s weather as its forerunners, then I must say that to-morrow’s rain is probable to such or such a degree. And the correctness of my statement depends upon whether I know the conditions under which rain must appear, more or less accurately and completely, and whether I relate those conditions properly. With regard to unconditioned probabilities which have nothing to do with the conditions of to-day’s weather as affecting to-morrow’s, but are simply observations statistically made concerning the number of rainy days, the case is quite different. The distinction between these two cases is of importance to the criminalist because the substitution of one for the other, or the confusion of one with the other, will cause him to confuse and falsely to interpret the probability before him. Suppose, e.g., that a murder has happened in Vienna, and suppose that I declare immediately after the crime and in full knowledge of the facts, that according to the facts, i.e., according to the conditions which lead to the discovery of the criminal, there is such and such a degree of probability for this discovery. Such a declaration means that I have calculated a conditioned probability. Suppose that on the other hand, I declare that of the murders occurring in Vienna in the course of ten years, so and so many are unexplained with regard to the personality of the criminal, so and so many were explained within such and such a time,—and consequently the probability of a discovery in the case before us is so and so great. In the latter case I have spoken of unconditioned probability. Unconditioned probability may be studied by itself and the event compared with it, but it must never be counted on, for the positive cases have already been reckoned with in the unconditioned percentage, and therefore should not be counted another time. Naturally, in practice, neither form of probability is frequently calculated in figures; only an approximate interpretation of both is made. Suppose that I hear of a certain crime and the fact that a footprint has been found. If without knowing further details, I cry out: “Oh! Footprints bring little to light!” I have thereby asserted that the statistical verdict in such cases shows an unfavorable percentage of unconditional probability with regard to positive results. But suppose that I have examined the footprint and have tested it with regard to the other circumstances, and then declared: “Under the conditions before us it is to be expected that the footprint will lead to results”—then I have declared, “According to the conditions the conditioned probability of a positive result is great.” Both assertions may be correct, but it would be false to unite them and to say, “The conditions for results are very favorable in the case before us, but generally hardly anything is gained by means of footprints, and hence the probability in this case is small.” This would be false because the few favorable results as against the many unfavorable ones have already been considered, and have already determined the percentage, so that they should not again be used.

Such mistakes are made particularly when determining the complicity of the accused. Suppose we say that the manner of the crime makes it highly probable that the criminal should be a skilful, frequently-punished thief, i.e., our probability is conditioned. Now we proceed to unconditioned probability by saying: “It is a well-known fact that frequently-punished thieves often steal again, and we have therefore two reasons for the assumption that X, of whom both circumstances are true, was the criminal.” But as a matter of fact we are dealing with only one identical probability which has merely been counted in two ways. Such inferences are not altogether dangerous because their incorrectness is open to view; but where they are more concealed great harm may be done in this way.

A further subdivision of probability is made by Kirchmann.[148] He distinguished:

(1) General probability, which depends upon the causes or consequences of some single uncertain result, and derives its character from them. An example of the dependence on causes is the collective weather prophecy, and of dependence on consequences is Aristotle’s dictum, that because we see the stars turn the earth must stand still. Two sciences especially depend upon such probabilities: history and law, more properly the practice and use of criminal law. Information imparted by men is used in both sciences; this information is made up of effects and hence the occurrence is inferred from as cause.

(2) Inductive probability. Single events which must be true, form the foundation, and the result passes to a valid universal. (Especially made use of in the natural sciences, e.g., in diseases caused by bacilli; in case X we find the appearance A and in diseases of like cause Y and Z, we also find the appearance A. It is therefore probable that all diseases caused by bacilli will manifest the symptom A.)

(3) Mathematical Probability. This infers that A is connected either with B or C or D, and asks the degree of probability. I. e.: A woman is brought to bed either with a boy or a girl: therefore the probability that a boy will be born is one-half.

Of these forms of probability the first two are of equal importance to us, the third rarely of value, because we lack arithmetical cases and because probability of that kind is only of transitory worth and has always to be so studied as to lead to an actual counting of cases. It is of this form of probability that Mill advises to know, before applying a calculation of probability, the necessary facts, i.e., the relative frequency with which the various events occur, and to understand clearly the causes of these events. If statistical tables show that five of every hundred men reach, on an average, seventy years, the inference is valid because it expresses the existent relation between the causes which prolong or shorten life.

A further comparatively self-evident division is made by Cournot, who separates subjective probability from the possible probability pertaining to the events as such. The latter is objectively defined by Kries[149] in the following example:

“The throw of a regular die will reveal, in the great majority of cases, the same relation, and that will lead the mind to suppose it objectively valid. It hence follows, that the relation is changed if the shape of the die is changed.” But how “this objectively valid relation,” i.e., substantiation of probability, is to be thought of, remains as unclear as the regular results of statistics do anyway. It is hence a question whether anything is gained when the form of calculation is known.

Kries says, “Mathematicians, in determining the laws of probability, have subordinated every series of similar cases which take one course or another as if the constancy of general conditions, the independence and chance equivalence of single events, were identical throughout. Hence, we find there are certain simple rules according to which the probability of a case may be calculated from the number of successes in cases observed until this one and from which, therefore, the probability for the appearance of all similar cases may be derived. These rules are established without any exception whatever.” This statement is not inaccurate because the general applicability of the rules is brought forward and its use defended in cases where the presuppositions do not agree. Hence, there are delusory results, e.g., in the calculation of mortality, of the statements of witnesses and judicial deliverances. These do not proceed according to the schema of the ordinary play of accident. The application, therefore, can be valid only if the constancy of general conditions may be reliably assumed.

But this evidently is valid only with regard to unconditioned probability which only at great intervals and transiently may influence our practical work. For, however well I may know that according to statistics every xth witness is punished for perjury, I will not be frightened at the approach of my xth witness though he is likely, according to statistics, to lie. In such cases we are not fooled, but where events are confused we still are likely to forget that probabilities may be counted only from great series of figures in which the experiences of individuals are quite lost.

Nevertheless figures and the conditions of figures with regard to probability exercise great influence upon everybody; so great indeed, that we really must beware of going too far in the use of figures. Mill cites a case of a wounded Frenchman. Suppose a regiment made up of 999 Englishmen and one Frenchman is attacked and one man is wounded. No one would believe the account that this one Frenchman was the one wounded. Kant says significantly: “If anybody sends his doctor 9 ducats by his servant, the doctor certainly supposes that the servant has either lost or otherwise disposed of one ducat.” These are merely probabilities which depend upon habits. So, it may be supposed that a handkerchief has been lost if only eleven are found, or people may wonder at the doctor’s ordering a tablespoonful every five quarters of an hour, or if a job is announced with $2487 a year as salary.

But just as we presuppose that wherever the human will played any part, regular forms will come to light, so we begin to doubt that such forms will occur where we find that accident, natural law, or the unplanned coöperation of men were determining factors. If I permit anybody to count up accidentally concurrent things and he announces that their number is one hundred, I shall probably have him count over again. I shall be surprised to hear that somebody’s collection contains exactly 1000 pieces, and when any one cites a distance of 300 steps I will suppose that he had made an approximate estimation but had not counted the steps. This fact is well known to people who do not care about accuracy, or who want to give their statements the greatest possible appearance of correctness; hence, in citing figures, they make use of especially irregular numbers, e.g. 1739, 7/8, 3.25%, etc. I know a case of a vote of jurymen in which even the proportion of votes had to be rendered probable. The same jury had to pass that day on three small cases. In the first case the proportion was 8 for, 4 against, the second case showed the same proportion and the third case the same. But when the foreman observed the proportion he announced that one juryman must change his vote because the same proportion three times running would appear too improbable! If we want to know the reason for our superior trust in irregularity in such cases, it is to be found in the fact that experience shows nature, in spite of all her marvelous orderliness in the large, to be completely free, and hence irregular in little things. Hence, as Mill shows in more detail, we expect no identity of form in nature. We do not expect next year to have the same order of days as this year, and we never wonder when some suggestive regularity is broken by a new event. Once it was supposed that all men were either black or white, and then red men were discovered in America. Now just exactly such suppositions cause the greatest difficulties, because we do not know the limits of natural law. For example, we do not doubt that all bodies on earth have weight. And we expect to find no exception to this rule on reaching some undiscovered island on our planet; all bodies will have weight there as well as everywhere else. But the possibility of the existence of red men had to be granted even before the discovery of America. Now where is the difference between the propositions: All bodies have weight, and, All men are either white or black? It may be said circularly the first is a natural law and the second is not. But why not? Might not the human body be so organized that according to the natural law it would be impossible for red men to exist? And what accurate knowledge have we of pigmentation? Has anybody ever seen a green horse? And is the accident that nobody has ever seen one to prevent the discovery of green horses in the heart of Africa? May, perhaps, somebody not breed green horses by crossings or other experiments? Or is the existence of green horses contrary to some unknown but invincible natural law? Perhaps somebody may have a green horse to-morrow; perhaps it is as impossible as water running up hill.