Descartes’ Philosophy: Existence of God and the Human Soul
Part 4 of the Discourse on Method: Reasons for the Existence of God and the Human Soul
Certainty and Cogito Ergo Sum
Analysis of the consequences of “Cogito ergo sum” (I think, therefore I am):
- Thinking is the essence.
- The soul is distinct from the body (substantial anthropological dualism).
- Cartesian substance dualism.
- Knowledge of the soul is evident and raises the criterion of truth: the two notes of evidence are clarity and distinction.
- Immortality of the soul.
Substance
A substance is something that exists and needs no other to exist. Therefore, strictly speaking, there is only one substance: God. When Descartes qualifies the bodies or the “self” as substances, he applies the concept in an analogical mode, as the “self” and the bodies have some independence from other beings, but both have been created and, therefore, depend on God.
Substances are essentially characterized by their attributes. There are three (infinity, thought, and extension), so there are three types of substances: infinite substance, thinking substance, and extended substance. Secondly, substances other than the infinite are the different ways that modifications can undergo.
- Extended substance or body: A substance whose attribute is extension.
- Infinite substance: God. A substance whose attribute is infinity or perfection.
- Thinking substance: A substance whose attribute is thought. It is identified with the “self” or soul.
Descartes’ Method
Descartes suggested nothing less than reshaping human knowledge, for which he resolved to doubt everything of which he did not have immediate and undeniable certainty. He noticed that many times the fluctuating testimony of the senses deceived him, sometimes he believed he was awake when he was asleep, and reasoned deductions and calculations obtained results that ultimately were discovered to be erroneous. But finally, he realized that he had something he could not doubt, that is, self-doubt, and always with the feeling of thinking came the feeling of being. All my thoughts are accompanied by the certainty of being me who is holding them.
Rationalism and the Search for Fundamental Truths
To understand rationalism, one must find within oneself the fundamental truths from which it is possible to deduce the whole edifice of our knowledge. This starting point has to be a truth that is absolutely certain, about which doubt cannot be exercised. The search for this starting point requires the task of removing all knowledge, ideas, and beliefs that do not appear absolutely certain: one must remove everything that is possibly doubtful. Hence, it begins with doubt, which is a methodological question (not skeptical or existential) that is required at the time of his analytical method.
Radicality of Doubt
Doubt everything possible; we doubt even our own doubts.
Reasons to Doubt Our Knowledge
- The senses often deceive us, and it is prudent never to trust completely those who have deceived us once. But doubts about the senses allow us to doubt that things are how we perceive them, not that there are no such things.
- The inability to distinguish dream from waking. This reason to doubt appears to affect the existence of things and the world, but not certain mathematical truths (asleep or awake, in Euclidean geometry, the three internal angles of a triangle add up to 180 degrees).
- The hypothesis of an evil genius of extreme power and intelligence that makes every effort to mislead, an extension of the doubt to the whole field of knowledge.
The Ontological Argument for the Existence of God
The argument used is the ontological argument. St. Anselm of Canterbury was the first to formulate a proof of the existence of God from the very idea of God. The argument, in summary, is this: God is, by definition, a being possessing all perfections in the highest degree, yet existence is a perfection, and therefore existence is part of the divine perfections; then God exists.
Thomas Aquinas and Kant would oppose this argument: that existence is not a perfection adds nothing to the concept or essence of a thing.
Conclusion of the Ontological Argument
The ontological argument tells us that the existence of God is within his own essence because if he did not exist, he would lack the perfection of existence (this has received much criticism).
Idea
Thinking that is “like a picture of a thing.” They are representations. Ideas are neither true nor false, since falsity or truth only occurs in judgments. Ideas have a twofold aspect:
- Their formal reality, that is, essentially what defines their being as modes of thinking. From this perspective, all ideas are equal.
- Their objective reality, considered as images that represent things, and then they are very different from each other. Some seem to me to be born with me (innate), others strange and coming from outside (adventitious), and others made and invented by myself (factitious).
Evidence
What is clear is attributable to knowledge (subjectively) or the known object (objectively). Objectively, the obvious is the object of an intuition of reason: simple natures. Subjectively, the obvious is the result of such knowledge intuition. Therefore, it is immediately evident truth. Not all knowledge is obvious, as some are also known by the deduction of reason.