10 DOGMATISM AND EVOLUTION 



regard one of these as supreme, the others being substantial only 

 in a secondary sense, as dependent for their existence on the 

 supreme substance, or God, alone. Thus the existence of God 

 has a unique place in the rationalistic scheme of things. It 

 belongs, in a way, to both kinds of truth. It is a fact evident to 

 reason, and the necessary presupposition of all other facts. 



The development of rationalism in the seventeenth century 

 was followed by an equally brilliant development of empiricism 

 in the first half of the eighteenth century. Bacon at last came 

 into his own. The movement is commonly regarded as dating 

 from the publication of Locke's Essay concerning Human Under- 

 standing in 1690. Against the common view it has been urged 

 with much force that Locke was at least as much a rationalist as 

 an empiricist; and, indeed, his direct debt seems to be far greater 

 to Descartes and Hobbes than to Bacon. His theory of mathe- 

 matics and ethics is strongly rationalistic. He believes these 

 sciences are concerned wholly with the relations between ideas 

 in our own minds, and are in need of no confirmation from experi- 

 ence. The ideas of which they treat are arbitrarily put together 

 by us; and the principal caution which we must observe in their 

 manipulation is to define accurately and use consistently the 

 terms by which we choose to denote them. Locke therefore 

 accepts the distinction between intuitive and demonstrative 

 truths on the one hand and inductive probabilities on the other, 

 and maintains that the latter can never through any process of 

 experience be raised to complete certainty. He believes, for 

 example, that the existence of each one of us is intuitively certain 

 to himself, and that the existence of God is demonstrably certain ; 

 while the existence of other persons and things can only be morally 

 certain, that is to say, true enough for all practical purposes. 



On the other hand, there are two peculiarities in Locke's 

 doctrine which were very important for the future development 

 of empiricism. In the first place, he attacked one of the most 

 central positions of rationalism by maintaining that all our ideas 



