Dr. WHEWELL, ON THE FUNDAMENTAL ANTITHESIS OF PHILOSOPHY. 177 



These laws of motion, as I have endeavoured to shew in a paper already printed by the Society, 

 depend upon the idea of Cause, and involve necessary truths, which are necessarily implied in the 

 idea of cause ; — namely, that every change of motion must have a cause — that the effect is measured 

 by the cause ; — that re-action is equal and opposite to action. These principles are not derived from 

 experience. No one, I suppose, would derive from experience the principle, that every event must 

 have a cause. Every attempt to see the traces of cause in the world assumes this principle. I do 

 not say that these principles are anterior to experience ; for I have already, I hope, shewn, that 

 neither of the two elements of our knowledge is, or can be, anterior to the other. But the two ele- 

 ments are co-ordinate in the development of the human mind ; and the ideal element may be said to 

 be the origin of our knowledge with the more propriety of the two, inasmuch as our knowledge is 

 the relation of ideas. The other element of knowledge, in which sensation is concerned, and which 

 embodies, limits, and defines the necessary truths which express the relations of our ideas, may be 

 properly termed experience ; and I have, in the Memoir just quoted, endeavoured to shew how the 

 principles concerning mechanical causation, which I have just stated, are, by observation and experi- 

 ment, limited and defined, so that they become the laws of motion. And thus we see that such 

 knowledge is derived from ideas, in a sense quite as general and rigorous, to say the least, as that in 

 which it is derived from experience. 



2] . I will take another example of this ; although it is one less familiar, and the consideration 

 of it perhaps a little more difficult and obscure. The objects which we find in the world, for 

 instance, minerals and plants, are of different kinds; and according to their kinds, they are called by 

 various names, by means of which we know what we mean when we speak of them. The discrimi- 

 nation of these kind of objects, according to their different forms and other properties, is the business 

 of chemistry and botany. And this business of discrimination, and of consequent classification, 

 has been carried on from the first periods of the development of the human mind, by an industrious 

 and comprehensive series of observations and experiments ; the only way in which any portion of 

 the task could have been effected. But as the foundation of all this labour, and as a necessary 

 assumption during every part of its progress, there has been in men's minds the principle, that 

 objects are so distinguishable by resemblances and differences, that they may be named, and known 

 by their names. This principle is involved in the idea of a Name ; and without it no progress could 

 have been made. The principle may be briefly stated thus: — Intelligible Names of kinds are 

 possible. If we suppose this not to be so, language can no longer exist, nor could the business of 

 human life go on. If instead of having certain definite kinds of minerals, gold, iron, copper and 

 the like, of which the external forms and characters are constantly connected with the same properties 

 and qualities, there were no connexion between the appearance and the properties of the object ; — 

 if what seemed externally iron might turn out to resemble lead in its hardness ; and what seemed to 

 be gold during many trials, might at the next trial be found to be like copper; not only all the 

 uses of these minerals would fail, but they would not be distinguishable kinds of things, and the 

 names would be unmeaning. And if this entire uncertainty as to kind and properties prevailed 

 for all objects, the world would no longer be a world to which language was applicable. To man, 

 thus unable to distinguisli objects into kinds, and call them by names, all knowledge would be impos- 

 sible, and all definite apprehension of external objects would fade away into an inconceivable 

 confusion. In the very apprehension of objects as intelligibly sorted, there is involved a principle 

 which springs within us, contemporaneous, in its efficacy, with our first intelligent perception of the 

 kinds of things of whicii the world consists. AVe assume, as a necessary basis of our knowledge, 

 that things are of definite kinds; and the aim of chemistry, botany, and other sciences is, to find 

 marks of these kinds; and along with these, to learn their definitely-distinguislied properties. Even 

 here, therefore, where so large a portion of our knowledge comes from experience and observation, we 

 cannot proceed without a necessary truth derived from our ideas, as our fundamental principle 

 of knowledge. 



