Dr. VVHEWELL, ON THE FUNDAMENTAL ANTITHESIS OF PHILOSOPHY. 179 



and experience, experiment and observation are needed, not only, as we have said, to supply the 

 objective element of all knowledge — to embody, limit, define, and modify our ideas ; but this 

 intercourse with objects is also requisite to unfold and fix our ideas themselves. As we have already 

 said, ideas and facts can never be separated. Our ideas cannot be exercised and developed in any 

 other form than in their combination with facts, and therefore the trials, corrections, controversies, 

 by which the matter of our knowledge is collected, is also the only way in which the form of 

 it can be rightly fashioned. Experience is requisite to the clearness and distinctness of our ideas, 

 not because they are derived from experience, but because they can only be exercised upon ex- 

 perience. And this consideration sufficiently explains how it is that experiment and observation 

 have been the means, and the only means, by which men have been led to a knowledge of the 

 laws of nature. In reality, however, the necessary principles which flow from our ideas, and 

 which are the basis of such knowledge, have not only been inevitably assumed in the course of such 

 investigations, but have been often expressly promulgated in words by clear-minded philosophers, 

 long before their true interpretation was assigned by experiment. This has happened with regard 

 to such principles as those above mentioned ; That every event must have a cause; That reaction 

 is equal and opposite to action ; That the quantity of matter in the world cannot be increased or 

 diminished : and there would be no difficulty in finding similar enunciations of tiie other principles 

 above mentioned ; — That the kinds of things have definite differences, and that these differences 

 depend upon their elementary composition. In general, however, it may be allowed, that the 

 necessary principles which are involved in those laws of nature of which we have a knowledge 

 become then only clearly known, when the laws of nature are discovered which thus involve the 

 necessary ideal element. 



25. But since this is allowed, it may be further asked, how we are to distinguish between the 

 necessary principle which is derived from our ideas, and the law of nature which is learnt by expe- 

 rience. And to this we reply, that the necessary principle may be known by the condition which we 

 have already mentioned as belonging to such principles : — that it is impossible distinctly to conceive 

 the contrary. We cannot conceive an event without a cause, except we abandon all distinct idea of 

 cause ; we cannot distinctly conceive two straight lines inclosing space ; and if we seem to con- 

 ceive this, it is only because we conceive indistinctly. We cannot conceive 5 and 3 making 7 or 9 ; 

 if a person were to say that he could conceive this, we should know that he was a person of imma- 

 ture or rude or bewildered ideas, whose conceptions had no distinctness. And thus we may take it 

 as the mark of a necessary truth, that we cannot conceive the contrary distinctly. 



26. If it be asked what is the test of distinct conception (since it is upon the distinctness 

 of conception that the matter depends), we may consider what answer we should give to this question 

 if it were asked with regard to the truths of geometry. If we doubted whether any one had 

 these distinct conceptions which enable him to see the necessary nature of geometrical truth, 

 we should inquire if lie could understand the axioms as axioms, and could follow, as demon- 

 strative, the reasonings which are founded upon them. If this were so, we should be ready to 

 pnmounce that he had distinct ideas of space, in the sense now supposed. And the same answer 

 may be given in any other case. That reasoner has distinct conceptions of mechanical causes who 

 can see the axioms of mechanics as axioms, and can follow the demonstrations derived from them as 

 demonstrations. If it be said that the science, as presented to him, may be erroneously constructed ; 

 that the axioms may not be axioms, and tiierefore the demonstrations may i)e futile, we still reply, 

 that the same might be said with regard to geometry : and yet that tile possibility of this does 

 not lead us to doubt either of the trutii or of the necessary nature of the pro])ositions contained in 

 Euclid's Elements. We may add further, that although, no doubt, the authors of elementary 

 books may be persons of confused minds, who present as axioms what are not axiomatic truths ; 

 yet that in general, what is presented as an axiom by a thoughtful man, though it may include 

 some false interpretation or application of our ideas, will also generally include some principle 

 vhich really is necessarily true, and which would still he involved in the axiom, if it were cor- 



Voi.. VIII. Pabt II. Aa 



