Note 211 — Chapter XX · (continued 2)

A calculation was published not long since, said to be on the authority of an eminent living philosopher, according to which, granting a moderate probability that each of twelve jurors would decide rightly, the chances in favour of the rectitude of their unanimous verdict were made something extravagantly high, I think about 8000 to 1. It is more easy to perceive the the fallacies of this pretended demonstration, than to explain how a man of great acuteness should have overlooked them. One among many is that it assumes the giving a verdict at all to be voluntary, whereas, in practice, the jury must decide one way or the other. We must deduct, therefore, a fraction expressing the probability that some of the twelve have wrongly conceded their opinions to the rest. One danger of this rather favourite application of mathematical principles to moral probabilities, as indeed it is of statistical tables (a remark of far wider extent), is that, by considering mankind merely as units, it practically habituates the mind to a moral and social levelling, as inconsistent with a just estimate of men as it is characteristic of the present age.