KANT.¹ 

"Being is evidently not a real predicate, or a concept of something that can be added to the concept of a thing. It is merely the admission of a thing, and of certain determinations in it. Logically, it is merely the copula of a judgment. The proposition, God is almighty, contains two concepts, each having its object, namely, God and almightiness. The small word is, is not an additional predicate, but only serves to put the predicate in relation to the subject. If, then, I take the subject (God) with all its predicates (including that of almightiness), and say, God is, or there is a God, I do not put a new predicate to the concept of God, but I only put the subject by itself, with all its predicates, in relation to my concept, as its object. Both must contain exactly the same kind of thing, and nothing can have been added to the concept, which expresses possibility only, by my thinking its object as simply, given and saying, it is. And thus the real does not contain more than the possible. A hundred real dollars do not contain a penny more than a hundred possible dollars. For as the latter signify the concept, the former the object and its position by itself, it is clear that, in case the former contained more than the latter, my concept would not express the whole object, and would not therefore be its adequate concept. In my financial position no doubt there exists more by one hundred real dollars, than by their concept only (that is their possibility), because in reality the object is not only contained analytically in my concept, but is added to my concept (which is a determination of my state), synthetically: but the conceived hundred dollars are not in the least increased through the existence which is outside my concept.

"By whatever and by however many predicates I may think a thing (even in completely determining it), nothing is really added to it, if I add that the thing exists. Otherwise, it would not be the same that exists, but something more than was contained in the concept, and I could not say that the exact object of my concept existed. Nay, even if I were to think in a thing all reality, except one, that one missing reality would not be supplied by my saying that so defective a thing exists, but it would exist with the same defect with which I thought it; or what exists would be different from what I thought. If, then, I try to conceive a being, as the highest reality (without any defect), the question still remains, whether it exists or not. For though in my concept there may be wanting nothing of the possible real content of a thing in general, something is wanting in its relation to my whole state of thinking, namely, that the knowledge of that object should be possible a posteriori also. And here we perceive the cause of our difficulty. If we were concerned with an object of our senses, I could not mistake the existence of a thing for the mere concept of it; for by the concept the object is thought as only in harmony with the general conditions of a possible empirical knowledge, while by its existence it is thought as contained in the whole content of experience. Through this connection with the content of the whole experience, the concept of an object is not in the least increased; our thought has only received through it one more possible perception. If, however, we are thinking existence through the pure category alone, we need not wonder that we cannot find any characteristic to distinguish it from mere possibility.

"Whatever, therefore, our concept of an object may contain, we must always step outside it, in order to attribute to it existence. With objects of the senses, this takes place through their connection with any one of my perceptions, according to empirical laws; with objects of pure thought, however, there is no means of knowing their existence, because it would have to be known entirely a priori, while our consciousness of every kind of existence, whether immediately by perception, or by conclusions which connect something with perception, belongs entirely to the unity of experience, and any existence outside that field, though it cannot be declared to be absolutely impossible, is a presupposition that cannot be justified by anything.

"The concept of a Supreme Being is, in many respects, a very useful idea, but, being an idea only, it is quite incapable of increasing, by itself alone, our knowledge with regard to what exists. It cannot even do so much as to inform us any further as to its possibility. The analytical characteristic of possibility, which consists in the absence of contradiction in mere positions (realities), cannot be denied to it; but the connection of all real properties in one and the same thing is a synthesis the possibility of which we cannot judge a priori because these realities are not given to us as such, and because, even if this were so, no judgment whatever takes place, it being necessary to look for the characteristic of the possibility of synthetical knowledge in experience only, to which the object of an idea can never belong. Thus we see that the celebrated Leibnitz is far from having achieved what we thought he had, namely, to understand a priori the possibility of so sublime an ideal Being.

"Time and labor therefore are lost on the famous ontological (Cartesian) proof of the existence of a Supreme Being from mere concepts; and a man might as well imagine that he could become richer in knowledge by mere ideas, as a merchant in capital, if, in order to improve his position, he were to add a few noughts to his cash account."

¹ Critique of Pure Reason. Translated by F. Max Muller. New York, 1896. P­483 et seq.