Note 114 — Chapter V · LOGIC OF THE STOICS.

(b) Inference. In their theory of illation,114 to which the Stoics attached special value, and on which they greatly prided themselves,115 chief attention was paid to hypothetical and disjunctive inferences.116 In regard to these forms of inference, the rules they laid down are well known:117 and from these forms they invariably take their examples, even when treating of inference (α) Hypothetical inference the original form. in general.118 According to Alexander,119 the hypothetical and disjunctive forms are held to be the only regular forms of inference;120 the categorical form is considered correct in point of fact, but defective in syllogistic form.121 In hypothetical inferences a distinction was also made between such as are connected and such as are disconnected.122 In connected inferences the Stoics look principally at the greater or less accuracy of expression,123 and partly at the difference between correctness of form and truth of matter.124 They also remark that true conclusions do not always extend the field of knowledge; and that those which do frequently depend on reasons conclusive for the individual, but not on proofs universally acknowledged.125 The main point, however, to be considered in dividing inferences is their (β) The five simple forms of hypothetical inference. logical form. There are, according to Chrysippus,126 who herein adopted the division of Theophrastus, five original forms of hypothetical inference, the accuracy of which is beyond dispute, and to which all other forms of inference may be referred and by which they may be tested.127 Yet even among these five, importance is attached to some in which the same sentence is repeated tautologically in the form of a conclusion,128 which proves how mechanical and barren must have been the formalism with which the Stoic logic abounds.