58 INTRODUCTION 



And the difference between them is that the truths of 

 reasoning are either ultimate self-evident principles or 

 truths which are reducible to such first principles by 

 a process of strict logical analysis, while any attempt to 

 analyze truths of fact into their ultimate grounds leads 

 to an infinite process, and they must finally be referred 

 to God as their ground eminenter 1 . 



Logical Principles of the Philosophy of Leibniz, (a) 

 Principle of Identity or Contradiction. 



With this division of human knowledge into two great 

 kinds we come in sight of the guiding principles of 

 Leibniz's philosophy, its logical pre-suppositions as dis- 

 tinct from its specific metaphysical doctrines. The logic 

 underlying the philosophies of Descartes and Spinoza 

 was a logic of abstract self-consistency 2 . In their view 

 all real knowledge must be ultimately of one kind. All 

 apparent knowledge that is not of that kind must be 

 regarded as entirely unreal and illusory. This was neces- 

 sarily involved in the position that there is no appeal 

 beyond the witness of consciousness to itself. ' The order 

 and connexion of ideas is the same as the order and 

 connexion of things 3 .' And, as all things must be re- 

 garded as ultimately referable to one ground or cause, so 

 all ideas must ultimately be referable to one standard ; 

 that is, must be linked together by one principle. The 

 standard must be that of self-evidence or absence of self- 

 % 



1 Cf. Monadology, 35~38- 



2 Not that this was perfectly evident to themselves. Descartes, 

 for instance, regards his method of doubt as superior to a logical 

 deduction, based on the principle of contradiction. * Here, if I am 

 not wrong,' says Eudoxus, ' you must be beginning to see that he 

 who can make a proper use of doubt will be able to deduce from 

 it very certain truths, nay rather, more certain and more useful 

 truths than those which we derive from the great principle we 

 usually lay down as the basis or centre to which all other principles 

 may be referred, "it is impossible that one and the same thing can both be 

 and not be." ' Recherche de la Verite par les lumieres natureUes, (Euvres de 

 Descartes (Cousin), vol. xi. p. 366. 



3 Spinoza, Ethics, Part ii. Prop. 7. 



