are demonstrable only on the presupposition of the causal principle. Notwithstanding the fact that B always follows A, and B does not appear in the absence of A, nevertheless our only ground of inference to a causal relation between A and B is the presupposition that B must have a cause. What then is the source of the causal principle? Mill answers: the same as all general propositions, experience, i. e., induction.—The circumlocution which is here apparent in Mill's argument has been clearly exposed by Stanley Jevons (in a series of articles under the title, Stuart Mill's Philosophy Tested—(1877–1879)—reprinted in Pure Logic and other Minor Works). Jevons had already demonstrated in his Principles of Science (1874) that the principle of identity is presupposed as the basis of all inference, because of the fact that the proof of an induction always consists of a deduction, which carries its inference back from a hypothetical proposition to the given impressions.
Mill's attempt therefore to furnish a system of logic which is wholly inductive did not succeed. This attempt forms the counterpart to Hegel's attempt to invent a logic which is wholly deductive. Mill tried to spin the forms of thought from their content, Hegel the content of thought from its forms. It is in these two men that the contrast between romanticism and positivism is most sharply drawn.
b. The pyschological presuppositions at the basis of Mill's logic come from James Mill's Analysis. They were the presuppositions of the "Associational Psychology." When, in his later years (1869), Stuart Mill published a new edition of the Analysis, in his appended notes he modified his psychological theory. Following Alexander Bain (whose chief works are The Senses and the
