The difference between Pure and Empirical KnowledgeThere can be no doubt that all our knowledge begins with experience. For how is it possiblethat the faculty of cognition should be awakened into exercise other than by objects whichaffect our senses, and partly of themselves produce representations, partly rouse our powersof understanding into activity, to compare, to connect, or to separate these, and so to convertthe raw material of our sense impressions into a knowledge of objects, which is called"experience"? Chronologically, therefore, no human knowledge is antecedent to experience,but rather begins with it. Term "knowledgea priori," therefore, in the rest of this work, weshall understand something not just independent of this or that kind of experience, butsomething absolutely independent of any experience. Opposed to this is empiricalknowledge, or that which is possible onlya posteriori, that is, through experience.Knowledgea prioriis either pure or impure. Pure knowledgea prioriis that with which noempirical element is mixed up. For example, the proposition, "Every change has a cause," is apropositiona priori, but impure, because change is a conception which can only be derivedfrom experience.The Human Intellect, even in an Unphilosophic State, is in Possessionof Certain Cognitions “a priori”Experience teaches us that this or that object is constituted in such-and-such a manner, butnot that it could not possibly exist otherwise. Now, first, if we have a proposition whichcontains the idea of necessity in its very definition, and, additionally, it is not derived fromany other proposition (unless from one equally involving the idea of necessity), it isabsolutely a priori. Secondly, an empirical judgement never exhibits strict and absolute, butonly assumed and comparative, universality (by induction); therefore, the most we can say is:"so far as we have observed, there is no exception to this or that rule." If, on the other hand, ajudgement carries strict and absolute universality (that is, admits of no possible exception), itis not derived from experience, but is valid absolutely a priori. The proposition, "Everychange must have a cause," will amply serve our purpose. In the latter case, indeed, theconception of a cause so plainly involves the conception of a necessity of connection with aneffect, and of a strict universality of the law, that the very notion of a cause would entirelydisappear, were we to derive it, like David Hume, from a frequent association of whathappens with that which precedes; and the habit thence originating of connectingrepresentations - the necessity inherent in the judgement being therefore merely subjective.Besides, without seeking for such examples of principles existing a priori in cognition, wemight easily show that such principles are the indispensable basis of the possibility ofexperience itself, and consequently prove their existence a priori. For whence could ourexperience itself acquire certainty, if all the rules on which it depends were themselvesempirical, and consequently fortuitous? No one, therefore, can admit the validity of the useof such rule as first principles. But, for the present, we may content ourselves with havingestablished the fact, that we do possess, and exercise, a faculty of pure a priori cognition; and,secondly, with having pointed out the proper tests of such cognition, namely, universalityand necessity.Philosophy needs a Science which shall Determine the Possibility,Principles, and Extent of Human Knowledge “a priori”the consideration that certain of our cognitions rise completely above the sphere of allpossible experience, and by means of conceptions, to which there exists in the whole extentof experience no corresponding object, seem to extend the range of our judgements beyondits bounds. And it is precisely in this "transcendental" or supersensible sphere, whereexperience affords us neither instruction nor guidance, that the investigations of reason lie,which, because of their importance, we consider far preferable to, and as having a far moreelevated aim than, all that the understanding can achieve within the sphere of sensephenomena. So high a value do we set upon these investigations, that even at the risk oferror, we persist in following them out, and permit neither doubt nor disregard norindifference to restrain us from the pursuit. These unavoidable problems of pure reason are:God, freedom (of will), and