In his consideration of the system of the world and the movement of the heavenly bodies, Descartes has worked out the mechanical view more fully. He thus comes to speak of the earth, the sun, &c., and of his conception of the circling motion of the heavenly bodies in the form of vortices: of metaphysical hypotheses as to how small particles pass into, out of, and through pores and act on one another; and finally to saltpetre and gunpowder.(35)Universal reflections should have the first claim on our attention; but on the other hand the transition to the determinate is accomplished in a system of Physics which is the result of observations and experiences, and this is done entirely by means of the understanding. Descartes thus mingles many observations with a metaphysic of this nature, and to us the result is hence obscure. In this philosophy the thinking treatment of empiricism is thus predominant, and a similar method has been adopted by philosophers from this time on. To Descartes and others, Philosophy had still the more indefinite significance of arriving at knowledge through thought, reflection, and reasoning. Speculative cognition, the derivation from the Notion, the free independent development of the matter itself, was first introduced by Fichte, and consequently what is now called philosophic knowledge is not yet separated in Descartes from the rest of scientific knowledge. In those times all the knowledge of mankind was called philosophy; in Descartes’
metaphysics we thus saw quite empirical reflection and reasoning from particular grounds, from experiences, facts, phenomena, being brought into play in the na?vest manner, and one has no sense of speculation in the matter. The strictly scientific element here really consisted mainly in the method of proof as it has long been made use of in geometry, and in the ordinary method of the formal logical syllogism. Hence it likewise happens that Philosophy, which ought to form a totality of the sciences, begins with logic and metaphysics; the second part is composed of ordinary physics and mathematics, mingled no doubt with metaphysical speculations, and the third part, ethics, deals with the nature of man, his duties, the state, the citizen. And this is the case with Descartes. The first part of the Principia philosophi? treats De principiis cognitionis human?, the second De principiis rerum materialium. This natural philosophy, as a philosophy of extension, is, however, none other than what a quite ordinary physics or mechanics might at that time be, and it is still quite hypothetical; we, on the other hand, accurately distinguish empirical physics and natural philosophy, first likewise pertains to thought.
3. Descartes never reached the third part, the philosophy of Mind, for, while he made a special study of physics, in the region of ethics he published one tract only, De passionibus. In this reference Descartes treats of thought and human freedom. He proves freedom from the fact of the soul thinking that the will is unrestrained, and of that constituting the perfection of mankind. And this is quite true. In respect to the freedom of the will he comes across the difficulty of how to reconcile it with the divine prescience. As free, man might do what is not ordained of God beforehand - this would conflict with the omnipotence and omniscience of God; and if everything is ordained of God, human freedom would thereby be done away with. Yet he does not solve the contradiction contained in these two different aspects without falling into difficulty. But conformably to the method which he adopts, and which we pointed out above (pp. 238,239), he says: "The human mind is finite, God’s power and predetermination are infinite; we are thus not capable of judging of the relationship in which the freedom of the human soul stands to the omnipotence and omniscience of God - but in self-consciousness we have the certainty of it given us as a fact. And we must hold only to what is certain."(36) When he proceeds further much appears to him still incapable of explanation; but we see obstinacy and caprice likewise exhibited in his stopping short at the assertion as to the best of his knowledge. The method of knowledge as set forth by Descartes, takes the form of a reasoning of the understanding, and is thus without special interest.
These, then, are the principal points in the Cartesian system. Some particular assertions made by Descartes, which have been specially instrumental in giving him fame, have still to be mentioned -particular forms which have been formerly considered in metaphysics, and likewise by Wolff. For example, in the first place we gather that Descartes regarded animals and other organisms as machines moved by another, and not possessing the principle of the spontaneity of thought within them(37) - a mechanical physiology, a cut and dry thought pertaining to the understanding, which is of no further importance. In the sharp opposition between thought and extension, the former is not considered as sensation, so that the latter can isolate itself. The organic must as body reduce itself to extension; any further development of this last thus only proves its dependence on the first determinations.
In the second place, the relation between soul and body now becomes an important question, that is, the return of the object within itself in such a way that thought posits itself in another, in matter.
