René Descartes: Foundations of Rationalism and the Pursuit of Certainty
René Descartes: A Foundation for Modern Philosophy
René Descartes lived during a period marked by uncertainty and confusion. This stemmed from the crisis experienced by individuals of the seventeenth century. The old ways of knowing were no longer valid and were actively debated and questioned by the intellectuals of the time. Two main factors contributed to this sense of unease and confusion: the scientific revolution and the loss of religious unity.
The scientific revolution dismantled theories that had been upheld for centuries, such as geocentrism, Aristotelian theories, and the scholastic method. Simultaneously, the loss of religious unity led to Christian Europe being divided into three groups: Catholic, Protestant, and Anglican. This division was the cause of many conflicts for centuries, such as the Thirty Years’ War.
The philosophy of the time attempted to approach the method and mathematical certainty with which science had made progress. Its mission was to create a foundation upon which new scientific theories could be related and made consistent, thus creating a new worldview. Two schools of thought emerged regarding how to achieve this: rationalism and empiricism. Both strands were based on the mathematical method and the observation of reality, and both valued the role of reason and experience in attaining knowledge.
However, rationalism, initiated by Descartes himself, gave reason the leading role. Empiricism, initiated by Thomas Hobbes, focused on experience as the basis of knowledge. Several key features characterized rationalist philosophy. On the one hand, there was confidence in human reason, arguing that only it could reach the truth. On the other hand, there was the affirmation of the existence of innate ideas, a Platonic trait claiming that knowledge is somehow present in the human soul.
Descartes’ Methodical Doubt
This excerpt from the book “Discourse on Method” by the French rationalist René Descartes deals with doubt. Doubt is a mechanism that the author chooses to use to analyze, from scratch, all the knowledge that until then had been considered true, and to determine if any of it remained valid thereafter. This requires a universal doubt, rejecting as false everything for which there is no evidence or certainty of its validity.
Descartes proposes rules for this that are known as “methodical doubt”:
- First, he rejects all information provided by the senses because these can give rise to deception, as has happened repeatedly throughout history.
- Secondly, he also accepts that human beings can be prone to errors in reasoning, and therefore he also doubts all arguments and demonstrations.
- Furthermore, he recognizes the difficulty of differentiating between dreams and thoughts, and that there is nothing that tells us exactly when we are dreaming or awake.
- Finally, although not in this text, Descartes also considered the existence of an “evil genius” who makes us see things as obvious when they are not.
This doubt, although universal and therefore denying all knowledge and truth, is not skeptical doubt. Quite the opposite: it is a step in a method to attain true knowledge. Furthermore, through it, the author concludes the first truth, absolute and unquestionable, and sets it as the bedrock of his new philosophy: “Cogito, ergo sum” (“I think, therefore I am”).
The Thinking Substance and the Criterion of Truth
From this first statement, the author concludes that although his body and everything around him were nothing but illusions, and he could pretend that they do not exist, he can never pretend not to think. Therefore, he claims that there is a part of us, which he identifies with the soul, separate from the body, and its mission is thinking. This is what he terms the “thinking substance” (res cogitans).
Furthermore, he also concludes that he can justify and demonstrate that first truth because it is clearly evident. Therefore, he states that only what is presented in a clear, obvious, and distinct manner can be regarded as true knowledge. This is the criterion of truth used by rationalists to decide whether knowledge is true or not: evidence.
The Existence of God and the Infinite Substance
In addition, he also realizes that in doubting, he ceases to be a perfect being since doubt is a flaw. To be is to be perfectly known. Hence, he concludes that the idea of perfection could only have been introduced by a being more perfect than himself because something imperfect cannot give rise to anything perfect, and nothing cannot arise from nothing. Descartes identifies the being that has put the idea of perfection in him with God, and he associates it with a new type of substance: the infinite substance (res infinita).
Thus, the author escapes solipsism, a position that argues that only the self can know anything for certain. This demonstration of God is strongly related to the ontological argument of St. Augustine, as both are based on the idea that one cannot deny the existence of God as a being who possesses all perfections, as this would lead to contradictions. It is also strongly related to the fourth way of St. Thomas Aquinas, which establishes a hierarchy of values and the need for someone who meets them all to the maximum degree.
The Extended Substance and Three Types of Ideas
Besides the two aforementioned substances, the thinking and the infinite, Descartes affirms the existence of a third substance that forms the rest of the world: the extended substance (res extensa). This is imperfect and finite, and it is part of the body, of matter.
Finally, the philosopher also identifies three types of ideas that are part of the thinking substance:
- Adventitious ideas: These come from experience and the senses and can be misleading.
- Fictitious ideas: These are invented ideas that do not come from sensory experience.
- Innate ideas: These are ideas whose origin is implicit in understanding itself. They are provided with evidence and are a confident basis for other knowledge.