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 190 G. E. MOORE : exists now," and thereby imply a distinction from its past and future existence. And this connexion of red and existence with the moment of time I mean by " now," would seem to be as necessary as any other connexion whatever. If it is true, it is necessarily true, and if false, necessarily false. If it is true, its contradictory is as fully impossible as the con- tradictory of 2 + 2 = 4. But the necessity thus involved in existential propositions does not do away with the importance of Kant's distinction between the empirical and the a priori. So far as he attempts to base it upon the fact that what is empirical alone is " given in experience" and may be referred to " sense," it must indeed be given up ; but as against the English philo- sophers, who held the same view about sense-knowledge, it retains its full weight. The Transcendental Deduction con- tains a perfectly valid answer to Hume's scepticism, and to empiricism in general. Philosophers of this school generally tend to deny the validity of any propositions except those about existents. Kant may be said to have pointed out that in any of these propositions, which the empiricists con- sidered to be the ultimate, if not the only, data of knowledge, there was involved by the very same logic on which they relied to support their views, not only the uniform and necessary succession of time, and the geometrical properties of space, but also the principles of substance and causality. He does not, indeed, thereby prove the truth of the axioms and principles in question ; but he shows that they are at least equally valid with, and more ultimate than, those upon which empiricism builds. Although, therefore, it seems no longer possible to hold, as Kant held, that a reference to existents is necessary to any proposition that is to claim the title of " knowledge," and that the truth of such propositions can alone claim immediate certainty ; although, on the con- trary, it seems that existential propositions are only a particular class of necessary proposition : yet the transcen- dental deduction is still important. A deduction from the " possibility of experience " does not indeed really represent the nature of Kant's argument. For the possibility of ex- perience presupposes that we have experience, and this again means that certain existential propositions are true : but this does not involve the truth of any particular exis- tential propositions ; although its truth is involved in theirs. What Kant really shows is that space and time and the categories are involved in particular propositions ; and this work is of greater value than a deduction from the possibility of experience would have been. He does not indeed recog- f