Descartes’ Proof of God’s Existence and the Method of Doubt

Posted on Jan 5, 2025 in Geology

The Existence of God According to Descartes

The existence of God is not innate. Descartes discovered the way to identify with God through infinity. This is not an advantageous or factitious way. Experience is not external, because experiences are always our special realities. Being shows how it is finite. Beings cannot be factitious. The comings and goings of finite beings proceed from the finite. That said, only the first cause is innate. I am limited (this demonstrates what I doubt), then the first existence has an infinite nature, since the first cause of my reason is infinite. God exists.

Descartes’ Demonstrations of God’s Existence

Descartes offers various demonstrations of God’s existence:

  1. Using an ontological argument, similar to Anselm’s: The first perfection is existence, therefore God is infinite.
  2. Using an argument based on the principle of cause and effect, a philosophical principle from Aristotle:
    • a) All that exists has a first cause that explains its existence.
    • b) The cause is always prior to the effect.

    According to this principle, God is the infinite being found in my reason. God cannot proceed from me, but from a being endowed with infinite existence. Therefore, this infinite being, God, exists.

  3. As a corollary to the second argument, Descartes explains that God must exist because of my own existence. I recognize myself as an imperfect being, certainly not my own cause. If I were, I would not deprive myself of any of the perfections that I find in God. Thus, a superior being must exist for me to exist.

Descartes’ Refutation of Radical Doubt

After demonstrating God’s existence, Descartes can refute radical doubt. He addresses the hypothesis of the “evil genius” with the following reasoning: To pretend to deceive is not a sign of perfection, but of weakness and malice. These imperfections cannot exist in God. Therefore, we can trust the truth that we find in demonstrations that are shown to us with evidence.

As for the second doubt, the confusion between wakefulness and sleep, which puts into question our belief in the existence of an external reality: Since God exists, and is infinitely good and truthful, He cannot allow me to be deceived into believing that the world exists. Therefore, the world, as an extramental reality, exists.

However, God only ensures the existence of the world, but does not guarantee that my perception of the world is correct. From this, it follows that:

  • Sensible knowledge remains under suspicion.
  • Of all the qualities perceived in the world, only the “primary qualities” (extension and movement) are mathematizable. The “secondary qualities” (odor, color, taste, etc.) cannot be known, since they cannot be translated into mathematical language, in which there is certainty.

Thus, the world is defined by Descartes as “res extensa” (extended thing). Finally, for Descartes, God is the one who ensures that our clear and distinct ideas are true. It is clear that clarity and distinction are not in themselves true, but the possession of these perfections reveals their divine origin. God cannot proceed from any falsehood.

Descartes’ Method: Rules for the Direction of the Mind

The goal is to create a universally valid and irrefutable philosophical system. Descartes uses mathematics (mathesis universalis) or the inductive-deductive method, also known as the analytical method. Reason is a capacity equal in all men, and the diversity of human opinions originates from the different ways of guiding it and the objects to which it is applied. Descartes calls human wisdom “bona mens” (reason).

Descartes’ Four Fundamental Rules

  1. Evidence: Something is evident when it is clear (easy, it is perfectly understood) and distinct (different, it is not confused with anything else). Nothing doubtful should be admitted. Evidence is the opposite of conjecture (any system that does not allow reaching evidence is not intuition), which is that which does not appear true immediately. The act of the soul to reach evidence is intuition (a mental faculty that allows us to capture primary things). Descartes understands intuition as “a conception of the pure and attentive spirit (mind), so easy and distinct, that absolutely no doubt remains regarding that which we think.”
  2. Analysis: This consists of dividing each of the difficulties to be examined into as many parts as possible to better solve them. Analysis means breaking down complex problems into simpler ones.
  3. Synthesis: This consists of driving thoughts in order, starting with the simplest and easiest objects to know, to gradually ascend to the most complex knowledge. This rule presupposes deduction, resolving each part starting from the easiest to the most complex.
  4. Enumeration: This is about reviewing the entire process, being sure not to leave anything out. “It consists of making such complete enumerations and such general reviews that we are sure not to omit anything.” Analysis and enumeration verify the synthesis.

All these rules are reduced to evidence: We must find the first evident truth from which all others are deduced. It is certainly the instrument to reach certainty.

Cartesian Doubt

Descartes conceived the idea of building a supreme science, which he called primary philosophy. This involves the destruction of old opinions through Cartesian doubt. Doubt is not skeptical; it is a habit of thought, a moment in which we are not capable of saying if something is true or false. To elaborate the first philosophy, an instrument is needed, hence it is called methodical doubt. It can be said that it is a universal doubt and that it is a provisional doubt. It does not extend to beliefs or morals, only to the plane of theory.

Descartes’ Doubts

  • The senses: “Sometimes when we see something from afar, it seems to us one thing, and when we get closer, it is another.” Therefore, the senses deceive us. We eliminate the senses and everything that is supported by them.
  • The external world: Due to the lack of a criterion to distinguish reality from a dream, and because the senses capture them, we doubt the external world.
  • One’s own reasoning: “My understanding can be mistaken when it reasons.” Descartes eliminates judgments as true knowledge.
  • The self: “There may exist a ‘little elf’ or ‘evil genius’ within me, continuously inducing me to error.” Thus, all the truths that could have been reached with the previous criteria are destroyed.

Descartes intends to reach a truth believed by himself, independent of any prior knowledge.