Descartes’ Philosophy: Reason, Method, and Existence
Descartes’ Philosophical Journey
He received a scholastic education, educated by the Jesuits. He lived during the scientific revolution and against Galilean processes, including the Thirty Years’ War.
The Central Questions of Modernity
The problems of knowledge, its source, and veracity are central questions of modernity. Man took refuge in that which is universal and offers some security: reason. Descartes opens a new phase in the seventeenth century called rationalism. The rationalists reject realism for idealism.
Descartes’ Contributions
Descartes wrote about a dozen philosophical and scientific works. He was a brilliant mathematician. He invented and developed analytic geometry, which marked his philosophical system and his understanding of the physical world. Descartes questioned all learned knowledge, which was confusing and scattered, reaching a stage of intense skepticism.
Descartes’ Concerns
The problems that Descartes was concerned about were: How can I safely move into the path of knowledge? Why the diversity of opinions, many of them contradictory, in philosophical thought? Why is science progressing while philosophy is not? His answer: Because philosophy lacks a proper method like mathematics.
The Nature of Reason
Reason has a unitary nature, and therefore knowledge that is the result of reason must also have a unifying effect. A correct method is needed to properly address reason.
The Tree of Knowledge
Philosophy is the tree of knowledge, with its roots in metaphysics, the trunk being natural philosophy, and the branches being the various sciences.
Descartes’ Method
Descartes defines the procedure as “the set of certain and easy rules through which, the fact that nothing false will ever be met as true, and knowledge will gradually increase, the latter being true.”
Mental Procedures for Organizing Knowledge
According to Descartes, the human mind uses two mental procedures for organizing knowledge:
- Intuition: Reason is able to capture an idea immediately and evidently, without the possibility of error.
- Deduction: Reason is able to discover the connections that exist between simple ideas to develop new ones.
Four Basic Rules of Method
In his Discourse on Method, Descartes identifies four basic rules to switch to other truths, thus verifying the steps given in successive rational deduction:
- The Evidence: Do not accept as true any proposition which is not self-evident. Intellectual intuition allows our minds to distinguish an idea that is manifestly evident, clear, and distinct.
- The Analysis: Resolve the problem being analyzed into its simplest parts.
- The Synthesis: Build complex knowledge from the simple elements obtained in the analysis using deduction.
- The Verification: Review all steps in the deduction for errors, ordering and listing the elements of knowledge.
This method, inspired by mathematics, is eminently rational. Descartes distrusts empirical experimentation as the data provided by the senses can be misleading.
Reasons for Doubt
- Data from the senses are a frequent source of deception.
- The confusion between waking and dream states; dreams are sometimes believed to be real.
- The ability of intelligence to establish reasoning, including mathematical proofs. Maybe we were created by a God who made us unable to distinguish truth from error. Conscious that this argument can lead to a slippery slope, he introduces the “thesis of the evil genius.” As God is infinitely good and unable to deceive, perhaps there is an “evil genius” that forces us to think wrongly, believing that we are right, or, what is the same, perhaps our intelligence capability is not sufficient to find the truth.
Cartesian Doubt
The Cartesian argument leads to absolute skepticism. Cartesian doubt is provisional. Skepticism is a prerequisite to achieving the indubitable.
The Intuition of Existence
The process takes Descartes to doubt everything except the only idea that cannot be doubted: the intuition of our own existence. The subject who thinks, exists. Cogito, ergo sum: I think, therefore I am.
Clarity and Certainty
Clarity and certainty are subjective criteria.
Ideas
- Adventitious: (From outside, like the idea of a “tree”).
- Factitious: (Ideas that have been made, like a “siren”).
- Innate: (Like the idea of God; as he is an imperfect being, a supremely perfect being has put the idea in him).
The Existence of God
God exists as res infinita, an infinite substance. It is part of God’s nature to prove the existence of God. God is infinitely good (eliminating the evil genius hypothesis). This ensures that ideas correspond to the outside world, providing objective certainty.