544 LOGIC OF THE MORAL SCIENCES. 



§ 5. While on the one hand Psychology is altogether, or principally, 

 a science of observation and experiment, Ethology, as I have conceived 

 it, is, as I have already remarked, altogether deductive. The one 

 ascertains the simple laws of Mind in general, the other traces their 

 operation in complex combinations of circumstances. Ethology stands 

 to Psychology in a relation very similar to that in which the various 

 branches of natural philosophy stand to mechanics. The principles of 

 Ethology are properly the middle principles, the axiomata media (as 

 Bacon would have said) of the science of mind : as distinguished, on 

 the one hand from the empirical laws resulting from simple observa- 

 tion, and on the other from the highest generalizations. 



And this seems a very proper place for a logical remark, which, 

 though of general application, is of peculiar importance in reference to 

 the present subject. Bacon has judiciously observed that the axiomata 

 media of every science principally constitute its value. The lowest 

 generalizations, until explained by and resolved into the middle princi- 

 ples of which they are the consequences, have only the imperfect 

 accuracy of empirical laws; while the most general laws are too 

 general, and include too few circumstances, to give sufficient indica- 

 tion of what happens in individual cases, where the circumstances are 

 almost always immensely numerous. In the importance, therefore, 

 which Bacon assigns, in every science, to the middle principles, it is 

 impossible not to agree with him. But I conceive him to have been 

 radically wrong in his doctrine respecting the mode in which these 

 axiomata media should be arrived at ; although there is no one propo- 

 sition laid do^vn in his works for which he has been so extravagantly 

 eulogized. He enunciates as an universal rule, that induction should 

 proceed fi'om the lowest to the middle principles, and fi-om those to the 

 highest, never I'eversing that order, and consequently leaving no room 

 for the discovery of new principles by way of deduction at all. It is 

 not to be conceived that a man of Bacon's sagacity could have fallen 

 into this mistake, if there had existed in his time, among the sciences 

 which treat of successive phenomena, one single instance of a deduc- 

 tive science, such as mechanics, astronomy, optics, acoustics, &:c., now 

 are. In those sciences it is evident that the higher and middle princi- 

 ples ai-e by no means derived from the lowest, but the reverse. In 

 some of them the very highest generalizations were those earliest as- 

 certained with any scientific exactness ; as, for example (in mechanics), 

 the laws of motion. Those general laws had not indeed at first the 

 acknowledged universality which they acquired after having been suc- 

 cessfully employed to explain many classes of phenomena to which 

 they were not originally seen to be applicable : as when the laws of 

 motion were einployed in conjunction with otlier laws to explain de- 

 ductively the celestial phenomena. Still, the fact remains, that the 

 propositions which were afterwards recognized as the most general 

 truths of the science, were, of all its accurate generalizations, those 

 earliest arrived at. Bacon's greatest mei'it cannot, therefore, consist, 

 as we are so often told that it did, in exploding the vicious method 

 pursued by the ancients of flying to the highest generalizations first, 

 and deducing the middle principles from them ; since this is neither a 

 ^^cious nor an exploded, but the universally accredited method of 

 modern science, and that to which it owes its greatest triumphs. The 

 error of ancient speculation did not consist in making the largest 



