The final position may be shortly illustrated by Mill's relation to his contemporaries.It will show briefly what were the alternatives between which he had to choose,and that,if that which he chose leads to error,there were at least equal errors on the other side.Mill frankly states in his preface that but for Whewell's History of the Inductive Sciences the corresponding part of his own book 'would probably not have been written.'He remarks with equal candour that Sir John Herschel,in his Discourse on the Study of Natural Philosophy,(96)had recognised the four methods.Herschel,however,was his only predecessor,and a more distinct and articulate exhibition of their nature was desirable.Herschel and Whewell had graduated at Cambridge in 1813and 1816.Both of them were able mathematicians,and,with their contemporary Babbage,had done much to introduce at their university the methods of analysis developed on the Continent.The university was gradually roused;Herschel won a great name in astronomy,and Whewell took in earlier life a very active part in promoting scientific studies in England.(97)Both of them had much closer acquaintance with the physical sciences than Mill,for whom they provided a useful store of materials.Herschel,though a friend of Whewell,approximates to Mill.A 'famous'review of Whewell's two books in the Quarterly of June 1841(98)gives his position;but although he seems to perceive the source of Whewell's weakness,he scarcely comes to close quarters.It is enough for my purpose to speak briefly of the points at issue between Mill and Whewell.
Whewell,like his most eminent contemporaries at Cambridge,was becoming aware that German speculation could no longer be overlooked.Herschel was son of a German;and Whewell's friends,Julius Hare (1795-1855)and Connop Thirlwall (1797-1875)were taking up the study of German.Their translation of Niebuhr's History of Rome (1828-1832)marked an epoch in English scholarship.Whewell meanwhile had read Kant,and been greatly impressed.Especially,as he says,he accepted Kant's theories of space,time,and,in some degree,causation,although he differed from Kant's doctrine as to other so-called 'fundamental ideas.'(99)He 'gladly acknowledges,'too,his obligations to the Scottish school.(100)In fact,it may be said that,like Sir W.Hamilton,he made a compromise between two modes of thought which very rapidly diverge from each other.Whewell begins his Philosophy of the Inductive Sciences by considering the fundamental antithesis of philosophy,which corresponds to the distinction between thoughts and things,necessity and experience,object and subject,and so forth.Time and space are,in his phrase,'fundamental ideas,'upon which are founded the mathematical sciences.But there are other 'fundamental ideas'--'cause,''media,''polarity,''chemical affinity resemblance,''excitability,'and 'final cause'--which in succession become the foundation of various sciences.
These fundamental ideas are,as he admits,something like 'innate ideas,'except that they can be 'developed.'They can somehow be 'superinduced upon facts,'and are not 'generated by experience.'I shall not attempt to explain a theory which seems to be radically incoherent,and which made no converts.It will be quite enough to notice two of the points of collision with Mill.Mill and Whewell agree(101)that the 'first law of motion'which asserts the uniform rectilinear motion of a body not acted upon by a force was unknown till the time of Galileo.Whewell admits further that,'historically speaking,'it was made 'by means of experiment.'We have,however,attained a point of view in which we ae that it might have been certainly known to be true,independently of experience,Mill naturally ridicules this doctrine,according to which we burden ourselves with 'truths independent of experience'and yet admit that they were proved 'by (or 'by means of')experiment.'The history is admitted on both sides.It had been observed that the motion of all bodies ceases unless they receive a new impulse.The statement was true,though vague,for all bodies upon the earth.But the progress of astronomy and exact sciences required a more precise statement.
Science has not simply to recognise that motion declines,but to show at what rate,and under what conditions it declines.Then,as we cannot measure 'absolute motion,'or assign any fixed point in space,we can obtain no rule as to absolute motion.If we assume,however,that we have to account not for motion but for change of motion,we can get a consistent 'law'which at once gives a sufficient account of many observed phenomena.We proceed to define force as the cause of change in motion.Then it becomes an identical proposition that all change of motion implies force,or that bodies not acted upon continue to move uniformly.Thus the definition of force takes the shape of an a priori axiom as to force.We imagine that instead of simply co-ordinating our experience we are 'applying a fundamental idea'to it,the idea,namely,of a 'cause'or 'force.'(102)The axiom is not 'independent of experience.'Rightly understood,the whole process is one of interpreting experience.Mill,however,is hardly correct in saying that the law was proved by experiment.
