Descartes’ Philosophy: Rules, Morality, Doubt, and Substance
1. Descartes’ Rules of Method
The first was to never admit anything as true without knowing the evidence that it was, that is, carefully avoiding precipitation and prevention and not including in my judgments nothing more than what was presented to my mind so clearly and distinctly that I had no reason to doubt it.
The second, to divide each of the difficulties I examined into as many parts as possible and into as many as required for its best solution.
The third, to drive my thoughts, starting with the simplest objects and the easiest to learn, to go slowly, rising as if by degrees to the knowledge of the most complex, and assuming an order even among those who did not precede naturally each other.
And finally, to do all enumerations so complete and reviews so general that I was sure not to miss anything.
2. Descartes’ Provisional Morality
These are four rules. The recent is the ideal choice for professional use.
The first was to obey the laws and customs of my country, constantly keeping the religion in which God has granted me the grace to instruct me as a child, governing myself in other things as more moderate opinions and more away from any excess, which were commonly accepted in practice by the most sensible people I would have to live with.
My second maxim was to be as firm and resolute in my actions as I could and still so constantly in the most doubtful opinions, once resolved on it, as if they were very safe.
My third maxim was to try always to conquer myself rather than fortune, to alter my desires rather than the world order, and get used to believing that only our thoughts are entirely in our power so that, having done the best we could, as to all things external, what we cannot do is absolutely impossible for us.
Finally, in conclusion of this morality, I had the idea of reviewing the different occupations that men have in this life to try to choose the best, and without meaning that none of the others, thought that nothing better could be done than to continue where I was, that is, applying my entire life to the cultivation of my mind and everything possible to advance the knowledge of truth according to the method I had prescribed.
3. Methodical Doubt and the First Truth
Finally, given that the same thoughts we have while awake may also occur to us when we sleep, without, in that case, any of them being true, I resolved to pretend that everything that had previously entered my mind was no more true than the illusions of my dreams. But then I noticed that even trying to think this way, that everything is false, it was required that I, who thought, was something. And noticing that this truth, I think, therefore I am was so firm and secure that the most extravagant suppositions of the skeptics were not able to move it, I thought I could accept it without scruple as the first principle of philosophy I sought.
4. The Three Substances: Thinking or Soul, Infinite or God, and Extensive or Body
Reason and Reality: The Theory of the Three Substances
Descartes defines substance as a thing that exists in such a way that it needs no other to exist.
Thinking Substance (Res Cogitans)
The thinking self is the first substance, which is the first truth or certainty. Universal doubt and methodically takes the subject to know the existence of this reality. The fundamental attribute of this substance is thought or consciousness.
Infinite Substance (Res Infinitas)
The second is the infinite substance or God. For Descartes, the thinking self is not perfect but has the idea of perfection (God). It is an uncreated substance that thinks and that is the cause of all created beings. God is a substance that is infinite, eternal, immutable, independent, omniscient, and omnipotent. God is the guarantee of veracity.
All that is in us comes from God.
Evidence of the Existence of the Substance God
a) The idea of perfect and infinite. Part of the idea of perfection and infinity that the subject can have, despite not being the subject neither perfect nor infinite. I recognize the finitude of me is the opposite of infinity that I know of God. He is the necessary cause of the idea of him in me. Descartes is the attribute of infinity.
b) The contingency of self. This argument is an explanation of the first test but introduces the principle of causality and blends the ideas of contingency and maintenance of created beings. Here Descartes comes to God as the cause of his being imperfect and finite. He claims that as I am not infinite and I have all the perfections, the being who has all the perfections is caused by this fact itself, and therefore exists.
c) The ontological argument. This is the most known of Descartes. The outline of the proof is the following: existence is a perfection, God has every perfection, then God exists.
The metaphysics of Cartesian and subsequent philosophies inevitably tend to show stocks through subjective mental acts. Kant later ruins the whole Cartesian metaphysics and opens a new channel to philosophy.
Extended Substance (Res Extensa)
The third substance is represented by material things (res extensa). This substance is a fundamental attribute of extension, and three dimensions: shape, position, and movement.
Descartes’ metaphysics without mishap leads to physics. The soul is defined by thought. The body is defined by the extension. We must consider two parts of Cartesian physics: mechanics and the theory of matter.
Descartes’ physics is mechanistic. Mechanism is the philosophical doctrine that explains the reality from efficient causality, that is, without reference to any purpose. Descartes does not want more stuff to explain phenomena and relationships that matter and motion.
Descartes’ physics is a pure mechanical quantity. The movement is stripped of whatever attacks clarity and purity of the concept: it is a change of position, which rejects Descartes.
The cause of the movement is twofold. A first cause is God. After entering the motion on the matter, God does not intervene again, except to continue to keep the matter in his being.
The second part of physics studies the theory of matter. Matter is nothing but space, pure extension, the very object of geometry. Secondary qualities we perceive sensible objects are intellectually inconceivable and therefore do not belong to reality. The matter comes down to the extension in length, breadth, and depth, with their modes, which are the limits of an extension for another.