(Cam. Phil. Soc. Feb. 11, 1850.)
The Cambridge Philosophical Society has willingly admitted among its proceedings not only contributions to science, but also to the philosophy of science; and it is to be presumed that this willingness will not be less if the speculations concerning the philosophy of science which are offered to the Society involve a reference to ancient authors. Induction, the process by which general truths are collected from particular examples, is one main point in such philosophy: and the comparison of the views of Induction entertained by ancient and modern writers has already attracted much notice. I do not intend now to go into this subject at any length; but there is a cardinal passage on the subject in Aristotle's Analytics, (Analyt. Prior. II. 25) which I wish to explain and discuss. I will first translate it, making such emendations as are requisite to render it intelligible and consistent, of which I shall afterwards give an account.
I will number the sentences of this chapter of Aristotle in order that I may afterwards be able to refer to them readily.
§ 1. "We must now proceed to observe that we have to examine not only syllogisms according to the aforesaid figures,—syllogisms logical and demonstrative,—but also rhetorical syllogisms,—and, speaking generally, any kind of proof by which belief is influenced, following any method.
§ 2. "All belief arises either from Syllogism or from Induction: [we must now therefore treat of Induction.]
§ 3. "Induction, and the Inductive Syllogism, is when by means of one extreme term we infer the other extreme term to be true of the middle term.
§ 4. "Thus if A, C, be the extremes, and B the mean, we have to show, by means of C, that A is true of B.
§ 5. "Thus let A be long-lived; B, that which has no gall-bladder; and C, particular long-lived animals, as elephant, horse, mule.
§ 6. "Then every C is A, for all the animals above named are long-lived.
§ 7. "Also every C is B, for all those animals are destitute of gall-bladder.