b. Descartes sought something in itself certain and true, which should neither be only true like the object of faith without knowledge, nor the sensuous and also sceptical certainty which is without truth. The whole of Philosophy as it had been carried on up to this time was vitiated by the constant pre-supposition of something as true, and in some measure, as in the Neo-Platonic philosophy, by not giving the form of scientific knowledge to its matter, or by not separating its moments. But to Descartes nothing is true which does not possess an inward evidence in consciousness, or which reason does not recognize so clearly and conclusively that any doubt regarding it is absolutely impossible. “Because we thus reject or declare to be false everything regarding which we can have any doubt at all, it is easy for us to suppose that there is no God, no heaven, no body - but we cannot therefore say that we do not exist, who think this. For it is contradictory to say that what thinks does not exist. Hence the knowledge that ‘I think, therefore I am,’ is what we arrive at first of all, and it is the most certain fact that offers itself to everyone who follows after philosophy in an orderly fashion. This is the best way of becoming acquainted with the nature of spirit and its diversity from body. For if we inquire who we are who can set forth as untrue everything which is different from ourselves, we clearly see that no extension, figure, change of position, nor any such thing which can be ascribed to body, constitutes our nature, but only thought alone; which is thus known earlier and more certainly than any corporeal thing.” (4) ‘I’ has thus significance here as thought, and not as individuality of self-consciousness. The second proposition of the Cartesian philosophy is hence the immediate certainty of thought. Certainty is only knowledge as such in its pure form as self-relating, and this is thought; thus then the unwieldy understanding makes its way on to the necessity of thought.
Descartes begins, just as Fichte did later on, with the ‘I’ as indubitably certain; I know that something is presented in me. By this Philosophy is at one stroke transplanted to quite another field and to quite another standpoint, namely to the sphere of subjectivity. Presuppositions in religion are given up; proof alone is sought for, and not the absolute content which disappears before abstract infinite subjectivity. There is in Descartes likewise a seething desire to speak from strong feeling, from the ordinary sensuous point of view, just as Bruno and so many others, each in his own fashion, express as individualities their particular conceptions of the world. To consider the content in itself is not the first matter; for I can abstract from all my conceptions, but not from the ‘I.’ We think this and that, and hence it is - is to give the common would-be-wise argument of those incapable of grasping the matter in point; that a determinate content exists is exactly what we are forced to doubt - there is nothing absolutely fixed. Thought is the entirely universal, but not merely because I can abstract, but because ‘I’ is thus simple, self-identical. Thought consequently comes first; the next determination arrived at, in direct connection with it, is the determination of Being. The ‘I think’ directly involves my Being; this, says Descartes, is the absolute basis of all Philosophy. (5) The determination of Being is in my ‘I’; this connection is itself the first matter. Thought as Being and Being as thought - that is my certainty, ‘I’; in the celebrated Cogito, ergo sum we thus have Thought and Being inseparably bound together.
