After 1829 I withdrew from attendance on the Debating Society. I had had enough of speechmaking, and was glad to carry on my private studies and meditations without any immediate call for outward assertion of their results. I found the fabric of my old and taught opinions giving way in many fresh places, and I never allowed it to fall to pieces, but was incessantly occupied in weaving it anew. I never, in the course of my transition, was content to remain, for ever so short a time, confused and unsettled. When I had taken in any new idea, I could not rest till I had adjusted its relation to my old opinions, and ascertained exactly how far its effect ought to extend in modifying or superseding them.
The conflicts which I had so often had to sustain in defending the theory of government laid down in Bentham’s and my father’s writings, and the acquaintance I had obtained with other schools of political thinking, made me aware of many things which that doctrine, professing to be a theory of government in general, ought to have made room for, and did not. But these things, as yet, remained with me rather as corrections to be made in applying the theory to practice, than as defects in the theory. I felt that politics could not be a science of specific experience; and that the accusations against the Benthamic theory of being a theory, of proceeding a priori by way of general reasoning, instead of Baconian experiment, showed complete ignorance of Bacon’s principles, and of the necessary conditions of experimental investigation. At this juncture appeared in the Edinburgh Review, Macaulay’s famous attack on my father’s Essay on Government. This gave me much to think about. I saw that Macaulay’s conception of the logic of politics was erroneous; that he stood up for the empirical mode of treating political phenomena, against the philosophical; that even in physical science his notions of philosophizing might have recognised Kepler, but would have excluded Newton and Laplace. But I could not help feeling, that though the tone was unbecoming (an error for which the writer, at a later period, made the most ample and honourable amends), there was truth in several of his strictures on my father’s treatment of the subject; that my father’s premises were really too narrow, and included but a small number of the general truths on which, in politics, the important consequences depend. Identity of interest between the governing body and the community at large is not, in any practical sense which can be attached to it, the only thing on which good government depends; neither can this identity of interest be secured by the mere conditions of election. I was not at all satisfied with the mode in which my father met the criticisms of Macaulay. He did not, as I thought he ought to have done, justify himself by saying, “I was not writing a scientific treatise on politics, I was writing an argument for parliamentary reform.” He treated Macaulay’s argument as simply irrational; an attack upon the reasoning faculty; an example of the saying of Hobbes, that when reason is against a man, a man will be against reason. This made me think that there was really something more fundamentally erroneous in my father’s conception of philosophical method, as applicable to politics, than I had hitherto supposed there was. But I did not at first see clearly what the error might be. At last it flashed upon me all at once in the course of other studies. In the early part of 1830 I had begun to put on paper the ideas on Logic (chiefly on the distinctions among Terms, and the import of Propositions) which had been suggested and in part worked out in the morning conversations already spoken of. Having secured these thoughts from being lost, I pushed on into the other parts of the subject, to try whether I could do anything further towards clearing up the theory of logic generally. I grappled at once with the problem of Induction, postponing that of Reasoning, on the ground that it is necessary to obtain premises before we can reason from them. Now, Induction is mainly a process for finding the causes of effects: and in attempting to fathom the mode of tracing causes and effects in physical science, I soon saw that in the more perfect of the sciences, we ascend, by generalization from particulars, to the tendencies of causes considered singly, and then reason downward from those separate tendencies, to the effect of the same causes when combined. I then asked myself, what is the ultimate analysis of this deductive process; the common theory of the syllogism evidently throwing no light upon it. My practice (learnt from Hobbes and my father) being to study abstract principles by means of the best concrete instances I could find, the Composition of Forces, in dynamics, occurred to me as the most complete example of the logical process I was investigating. On examining, accordingly, what the mind does when it applies the principle of the Composition of Forces, I found that it performs a simple act of addition. It adds the separate effect of the one force to the separate effect of
