Descartes’ Method and Metaphysics: A Summary
Descartes’ Method
Descartes understands method as a set of simple and easy rules, whereby those who exactly follow them will never take anything false to be true. Without unnecessary effort of mind, but always gradually increasing their scientific knowledge, they will arrive at the truth of everything that is within their capacity. The method consists of four rules, inspired by mathematics or geometry.
Rule of Order: Based on intuition, deduction, and logical induction.
- 1st Rule: The Rule of Evidence: This rule states the principle of evidence as a criterion of truth. An obvious truth is that which is presented with clarity and distinction. An idea is distinct when it cannot be confused with another. Through clear and distinct ideas, the understanding intuitively captures the simplest elements of which objects are composed. These are called simple natures. Intellectual evidence excludes precipitation, which is to admit as obvious something that is initially obscure and confusing.
- 2nd Rule: Analysis: This rule consists of the decomposition of a complex idea into its simplest elements. This allows for the understanding of simple natures. It is a good method of teaching.
- 3rd Rule: Synthesis: This rule consists of establishing a logical deduction, from the simple to the complex, based on simple natures.
- 4th Rule: Rule of Enumeration: This is the recording of the entire process. It is equivalent to an adequate and orderly intuition.
Metaphysics
Once the method is established, and since it is inspired by geometry, it is applied to other sciences to replicate the success achieved in mathematics. Descartes applies it to metaphysics, and since other sciences take their principles from it, it is first necessary to find an evident truth on which to build the philosophical system. Therefore, he decides to doubt everything in order to discover if there is something that resists all doubt. Cartesian doubt is characterized as:
- Methodological: The question of doubt is a methodological procedure to locate the beginning, which cannot be doubted, underpinning metaphysics.
- Theoretical: It applies only to the field of philosophical reflection; it is certainly not practical.
- Universal: Descartes questions all knowledge. The only things to which doubt does not apply are religious and practical matters.
Reasons for Doubt
The first reason is the reliability of the senses. If they sometimes deceive us, they can always do so. This reason is confirmed by the inability to distinguish the dream from wakefulness. A second reason to doubt is reasoning itself: we can be mistaken while reasoning. Finally, he questions the inability of intelligence itself: maybe God created us so that we are deceived. This would mean that in truth we are always in error. However, Descartes rejects the idea that God is good and can deceive, so he replaces it with the hypothesis of the existence of an evil genius, which does not require that we are always in error when thinking.
Cogito, Ergo Sum
This doubt has bracketed even the most common certainties: Descartes now distrusts the world’s existence and of external objects to it, even mathematical truths. The only thing that cannot be doubted is the doubting subject itself, the very subject who thinks the lack of sameness of things. From the act of doubting, an indubitable truth emerges: cogito, ergo sum, that is, I think, therefore I exist. This truth is the first taken by Descartes as the evident principle of truth in philosophy. It is a clear and distinct truth from which all other truths can be deduced. This evidence, “I think, therefore I exist,” is an intuition and it is an immutable principle, which cannot be doubted. For Descartes, thought is defined as any conscious act of the spirit, and the act of thinking is evident, not its content.
The Substance
Starting from the cogito, Descartes suggests that it is a res cogitans, a thing that thinks. He identifies “thing” with “substance,” and defines it as that which does not need anything else to exist except for God. Descartes divides substance into two:
- Infinite Substance: Descartes proves the existence of God from the idea of perfection. The fact that I doubt means that I am imperfect, and being aware of my imperfection implies that there is the idea of perfection in me. Ideas are mental acts on one side, and on the other, images that represent things. Ideas can be of several types:
- Adventitious Ideas: They come from outside experience, such as the idea of a butterfly.
- Factitious Ideas: They are constructed from the interference of imagination.
- Innate Ideas: These are ideas that the understanding has by nature. The idea of perfection must be an innate idea, put in my mind by a being that has the quality of perfection, God. The sample having doubts also shows that I am finite. The idea of infinity can only come from someone infinite. From there, Descartes concludes the necessity of God’s existence. The existence of the subject who thinks is thus demonstrated, and he believes that there is a perfect and extremely good God. God cannot delude us about the existence of the outside world or mathematical knowledge. Our errors are due to the precipitation with which we conduct our finite reasoning.
- Finite Substances: There are two kinds of finite substances: res cogitans (the soul) and res extensa (the body). Each substance corresponds to an attribute. Res cogitans is a thing that doubts. Thus, the attribute of the soul is thought. The attribute of bodies is extension. In the same way that we cannot imagine a subject that does not think, we cannot conceive of a body without length, width, and depth, which are characteristics of extension.