GENERAL PRINCIPLES 59 



contradiction in the ideas, which is simply another way 

 of describing the immediate witness of consciousness to 

 itself. True ideas must be clear and distinct in order 

 that it may be manifest that they are free from self- 

 contradiction. All real knowledge must either be imme- 

 diately recognizable as eternal and necessary truth, or 

 must be deducible from such truth by a formally or 

 mathematically conclusive process. Thus the philosophies 

 of Descartes and Spinoza were ruled by the principle of 

 contradiction, that A cannot both be A and not A, or 

 that necessary truths are 'identical propositions, whose 

 opposite involves an express contradiction 1 .' In other 

 words, they held that self-consciousness is self-consistent, 

 that it never absolutely contradicts itself. 



Now this is, so far as it goes, a perfectly sound doctrine. 

 Its fault is that it does not go far enough. Self -con- 

 sciousness is much more than merely self-consistent. Its 

 self-consistency is not immediate and on the surface. It 

 is not a mere negative self-identity of parts, without 

 regard to their specific content. To be self-consistent, 

 according to the principle of contradiction, is for a thing 

 to be itself, that is, to be 'not anything else.' But a 

 thing whose ultimate essence is to be l not anything else ' 

 is nothing. 'Nothing' is immediately self-consistent 

 quite as much as l something 2 .' In other words, all real 

 (not merely formal) self- consistency must be mediate, it 

 must have grounds. It must spring from the specific 

 nature of the self-consistent thing 3 . And thus, as Leibniz 

 contended, even axioms may require proof 4 . Their self- 



1 Monadology, 35. Cf. ibid. 31. The principle of contra- 

 diction is that ' in virtue of which we judge false that which 

 involves a contradiction, and true that which is opposed or contra- 

 dictory to the false.' 



2 Cf. Locke's Essay, bk. iv. ch. 8, 3 ; Eraser's ed., vol. ii. p. 293. 



3 Cf. Nouveaux Essais, bk. iv. ch. 7, 9 (E. 362 a ; G. v. 392) : ' In 

 the natural ' [i. e. logical] ' order, the statement that a thing is what 

 it is, is prior to the statement that it is not another thing.' 



4 Cf. Nouveaux Essais, bk. i. ch. 3, 24 (E. 222 a ; G. v. 98) : ' It 

 is one of my great maxims, that it is good to work out proofs of 



