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the individual human subject does not affect the nature of self-consciousness in itself or in its relation to knowledge. The force of Descartes’s argument really lies in this, that the world as an intelligible world exists only for a conscious self, and that therefore the unity of thought and being in self-consciousness is presupposed in all knowledge. Of this self it is true to say that it exists only as it thinks, and that it thinks always. Cogito, ergo sum is, as Descartes points out, not a syllogism, but the expression of an identity which is discerned by the simple intuition of the mind.[1] If it were otherwise, the major “omne quod cogitat existit” would require to have been known before the minor “cogito”; whereas on the contrary it is from the immediate consciousness of being as contained in self-consciousness that that major can alone be derived. Again, when Hobbes and others argued that thinking is or may be a property of a material substance, Descartes answers that the question whether the material and the thinking substance are one does not meet us at the outset, but can only be solved after we have considered what is involved in the conception of these different substances respectively.[2] In other words, to begin by treating thinking as a quality of a material substance, is to go outside of the intelligible world for an explanation of the intelligible world. It is to ask for something prior to that which is first in thought. If it be true that the consciousness of self is that from which we cannot abstract, that which is involved in the knowledge of anything, then to go beyond it and seek for a reason or explanation of it in anything else is to go beyond the beginning of knowledge; it is to ask for a knowledge before knowledge.

Descartes, however, is himself unfaithful to this point of view; for, strictly taken, it would involve the consequence, not only that there is nothing prior to the pure consciousness of self, but that there can be no object which is not in necessary relation to it. Hence there can be no absolute opposition between thought and anything else, no opposition which thought itself does not transcend. But Descartes commits the error of making thought the property of a substance, a res cogitans, which as such can immediately or directly apprehend nothing but thoughts or ideas; while, altogether outside of these thoughts and ideas, there is another substance characterized by the property of extension, and with which thought has nothing to do. Matter in space is thus changed, in Kantian language, into a “thing in itself,” an object out of all relation to the subject; and on the other hand, mind seems to be shut up in the magic circle of its own ideas, without any capacity of breaking through the circle or apprehending any reality but itself. Between thought and being, in spite of their subjective unity in self-consciousness, a great gulf seems still to be fixed, which cannot be crossed unless thought should become extended, or matter think. But to Descartes the dualism is absolute, because it is a presupposition with which he starts. Mind cannot go out of itself, cannot deal with anything but thought, without ceasing to be mind; and matter must cease to be matter ere it can lose its absolute externality, its nature as having partes extra partes, and acquire the unity of mind. They are opposed as the divisible and the indivisible, and there is no possible existence of matter in thought except a representative existence. The ideal (or, as Descartes calls it, objective) existence of matter in thought and the real (or, as Descartes calls it, formal) existence of matter out of thought are absolutely different and independent things.

It was, however, impossible for Descartes to be content with a subjective idealism that confined all knowledge to the tautological expression of self-consciousness “I am I,” “What I perceive I perceive.” If the individual is to Proof of existence
of God.
find in his self-consciousness the principle of all knowledge, there must be something in it which transcends the distinction of self and not self, which carries him beyond the limit of his own individuality. What then is the point where the subjective consciousness passes out into the objective, from which it seemed at first absolutely excluded? Descartes answers that it is through the connexion of the consciousness of self with the consciousness of God. It is because we find God in our minds that we find anything else. The proof of God’s existence is therefore the hinge on which the whole Cartesian philosophy turns, and it is necessary to examine the nature of it somewhat closely.

Descartes, in the first place, tries to extract a criterion of truth out of the cogito, ergo sum. Why am I assured of my own existence? It is because the conception of existence is at once and immediately involved in the consciousness of self. I can logically distinguish the two elements, but I cannot separate them; whenever I clearly and distinctly conceive the one, I am forced to think the other along with it. But this gives me a rule for all judgments whatever, a principle which is related to the cogito, ergo sum as the formal to the material principle of knowledge. Whatever we cannot separate from the clear and distinct conception of anything, necessarily belongs to it in reality; and on the other hand, whatever we can separate from the clear and distinct conception of anything, does not necessarily belong to it in reality. Let us therefore set an object clearly before us, let us sever it in thought so far as is possible from all other objects, and we shall at once be able to determine what properties and relations are essential and what are not essential to it. And if we find empirically that any object manifests a property or relation not involved in the clear and distinct conception of it, we can say with certainty that such property or relation does not belong to it except by arbitrary arrangement, or, in other words, by the external combination of things which in their own nature have no affinity or connexion.

Now, by the application of this principle, we might at once assure ourselves of many mathematical truths; but, as has been already shown, there is a point of view from which we may doubt even these, so long as the idea of a God that deceives us is not excluded. If it is not certain that there is a God that cannot lie, it is not certain that there is an objective matter in space to which mathematical truth applies. But the existence of God may be proved in two ways. In the first place, it may be proved through the principle of causality, which is a self-evident truth. We have in our mind many ideas, and according to the principle of causality, all these ideas must be derived from something that contains a “formal” reality which corresponds to their “objective” reality, i.e. which contains at least as much reality in its existence out of thought as they contain in their existence in thought. Now we might derive from ourselves not only the ideas of other minds like ourselves, but possibly also of material objects, since these are lower in the scale of existence than ourselves, and it is conceivable that the idea of them might be got by omitting some of the qualities which distinguish ourselves. But the idea of God, of a being who is eternal and immutable, all-powerful, all-wise, and all-good, cannot be derived from our own limited and imperfect existence. The origin, therefore, must be sought in a being who contains actually in himself all that is contained in our idea of him.

It was objected by some of the critics of Descartes that the idea of God as the infinite Being is merely negative, and that it is derived from the finite simply by abstracting from its conditions. Descartes answers that the case is just the reverse—the Descartes’s meta-physics. infinite is the positive idea, and the finite is the negative, and therefore the former is the presupposition of the latter. As Kant, at a later date, pointed out that space is not a general conception, abstracted from the ideas of particular spaces, and representing the common element in them, but that, on the contrary, the ideas of particular spaces are got by the limitation of the one infinite space that is prior to them, so Descartes maintains in general that the idea of the finite is had only by limitation of the infinite, and not the idea of the infinite by abstraction from the particular determinations of the finite. It is a necessary consequence of this that the self-consciousness of a finite being is bound up with the consciousness of the infinite. Hence the idea of God is not merely one among other ideas which we have, but it is the one idea that is necessary to our very existence as thinking beings, the idea through which alone we can think ourselves, or anything else. “I ought never to suppose,” says Descartes, “that my conception of the infinite is a negative idea, got by negation of the finite, just as I conceive repose to be merely negation of movement, and darkness merely the negation of light. On the contrary, I see manifestly that there is more reality in the infinite than in the finite substance, and that therefore I have in me the notion of the infinite, even in some sense prior to the notion of the finite, or, in other words, that the notion of myself in some sense presupposes the notion of God; for how could I doubt or desire, how could I be conscious of anything as a want, how could I know that I am not altogether perfect, if I had not in me the idea of a being more perfect than myself, by comparison with whom I recognize the defects of my own existence?”[3]

Descartes then goes on in various ways to illustrate the thesis that the consciousness of a defective and growing nature cannot give rise to the idea of infinite perfection, but on the contrary presupposes it. We could not think of a series of approximations unless there were somehow present to us the idea of the completed infinite as the goal we aim at. If we had not the consciousness of ourselves as finite in relation to the infinite, either we should not be conscious of
  1. Resp. ad secundas objectiones, p. 74,—quoting from the Elzevir edition.
  2. Resp. ad tertias object, p. 94.
  3. Meditatio tertia, p. 21.