therefore to remove knowledge, in order to make room for belief". 1 

 It is in the critique of Practical Reason that Kant argues for the 

 necessity and validity of making assumptions which theoretical 

 knowledge cannot disprove and which moral life demands. For 

 example, Practical Reason demands the freedom of the will. Man, 

 in the capacity of moral agent, as a member of the noumenal 

 world, gives laws to himself as a member of the realm of sense or 

 the phenomenal world. "Thou oughtest" implies "thou canst". 

 Because Kant separates so completely the rational and the sense 

 realms he seems to see no difficulty in positing the freedom of the 

 will. Freedom of the will is that autonomy, which constitutes the 

 will a law to itself, and it is possible because "Man, considering 

 himself ... as an intelligence, places himself in a different order 

 of things and in a relation to determining grounds of a wholly 

 different kind when on the one hand he thinks of himself as an 

 intelligence endowed with a will, and consequently with causality, 

 and when on the other he perceives himself as a phenomenon in 

 the world of sense (as he really is also) , and affirms that his causality 

 is subject to external determination according to laws of nature." 2 

 In theoretical knowledge the law of cause and effect has universal 

 applicability but it is a demand of the moral law that the will be 

 free. It is this freedom which makes possible obedience to the 

 Categorical Imperative, an imperative which the will is led to 

 utter because man is member not only of the rational world but 

 also of the sensible world. 



On the same basis, Kant goes on to show how man's practical 

 reason demands, likewise, two other Ideas, Immortality and God. 

 "The perfect accordance of the mind with the moral law is the 

 supreme condition of the summum bonum." 3 But such a condition 

 no rational being of the sensible world can attain at any moment 

 of his existence. It is therefore necessary to assume an infinite 

 progress towards that perfect accordance which again is possible, 

 Kant holds, only "on the supposition of an endless duration of 

 the existence and personality of the same rational being (which 

 is called the immortality of the soul)." 4 Therefore the immor- 

 tality of the soul is a second postulate of the Pure Practical Reason. 



1 The Critique of Pure Reason, Max Muller's Edn., P. 700. 



2 The Meta. of Morals, Abbott's tr., P. 77. 



3 Cr. of Pr. Reason, Abbott's tr., P. 218. 



4 Ibid. Pp. 218-9. 



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