Descartes: Reason, Method, and the Existence of God
Descartes
The Unity of Reason and Method, Doubt, and First Truth
Descartes believed that reason is unique, so wisdom needed to be unique too, and there would be only one science. Reason is known through two ways: intuition (perception of ideas directly, immediately ruling out any possibility of error; its act is itself evidence) and deduction (intuition laying successive passes of a term/idea to the next, and the memory involved). Having only one science, there is a unique method of applying these two modes of knowledge, formed by the processes of analysis (down to the simplest elements) and synthesis (deducing from the complex to the simple). To apply this method successfully in the enterprise of building a single science, we must find a truth that is absolutely true. To arrive at this truth, all possible doubt must be eliminated. The question is orderly, and according to Descartes, we have reason to doubt the following:
- Our senses can deceive us
- The possibility of confusing dreams with being awake, which casts doubt on the existence of things and the world
- Hypothesis of an evil genius
- God is a deceiver, allowing a continuous error in human understanding
Descartes finally found an absolute truth, immune to doubt: the existence of the subject who thinks and doubts. Because, even if I think wrong things, the fact that I think is not misleading, and moreover, I can doubt everything except that I doubt. This Descartes famously summed up as “I think, therefore I am” (Cogito ergo sum).
The first truth is the prototype of all truth and certainty because it is perceived clearly and distinctly. From this follows the criterion of certainty for Descartes: whatever is perceived with equal clarity and distinction will be true, and we can say with unwavering certainty.
Thought and Ideas
Descartes believes that we have thought (all that takes place in us so that we find ourselves immediately; thinking is understanding, willing, imagining, and feeling) and ideas (which are modes of thought and images of things, so that every idea is of one thing [objective reality]). Descartes argues first that thought is always thinking ideas and thinking with one that does not lie directly on things, but about ideas (contrary to what he thinks about philosophy).
There are three kinds of ideas:
- Adventitious: our experience seems to come from external sources
- Factitious: those that the mind builds from other ideas
- Inborn: which the soul has from the moment of its existence. Three ideas are natural, clear, and distinct, with which philosophy can be reconstructed on a sound basis: the idea of a perfect and infinite being (God), the thinking self (soul), and extension-res extensa (matter).
The Existence of God and the World
From the idea of God derives its existence through two arguments: the ontological, which says that the essence of God cannot be separated from their existence, and the causal, which argues that the idea of an infinite requires an infinite cause, as the objective reality requires a real reason given; then the infinite being (cause) exists.
The existence of the world is also demonstrated by Descartes from the existence of God. Since this exists and is infinitely good, it cannot let one be fooled into believing that the world exists; therefore, the world exists (provided that it consists exclusively of the extension and motion, primary qualities from which we deduce the physical laws of motion).
Substance, Soul, and Body
A substance is anything that exists so that it needs no other to exist. Descartes distinguishes three areas or domains of reality: the infinite substance (God), thinking substance (I), and extended substance (bodies).
For Descartes, the soul and body are distinct substances; the soul is a sphere of autonomous reality, independent of matter and therefore the body. These two substances interact in humans, according to Descartes, in the pineal gland: the point at which the soul connects with the body, acting on it and through which the spirits move.
Reason and Freedom
Descartes reports a fight between the lower and upper parts of the soul, between the passions and reason (and will). The passions are involuntary; they dominate the rational soul, are immediate, as they leave no room for reflection, and are not always consistent with reason. The soul uses trials led to strong knowledge of good and evil, according to which we drive the actions of our lives.
Liberty is the natural perfection of man and allows us to be masters of nature and our own actions. Its existence is certainly one of the first notions that are innate in us. It consists in choosing what is proposed by the understanding as good and true; it will bring understanding, discovering the order of reality by means of a deductive-mathematical way.
Cartesian Mechanism
Nature, for Descartes, is matter and motion, three-dimensional space, which excludes the void, and the cosmos is a machine composed of a series of vortices that are subject to certain laws of motion. There are three fundamental laws:
- Law of Inertia: everything remains in the state in which it is (rest/motion) if nothing changes it.
- Because of the system of vortices, the actual path is circular.
- Momentum will be distributed in clashes; one wins and one loses in the same proportion.