René Descartes: Methodical Doubt and Rationalism
René Descartes (Cartesius)
Life and Work
René Descartes was born in The Hague in 1596 and died in Stockholm of pneumonia in 1650. Descartes inaugurated modern rationalism in philosophy. He suggests that to escape skepticism, one must use skepticism as a remedy. This requires carrying skepticism to its limits.
Descartes’ Methodical Doubt
In Descartes’ meditations, metaphysical doubt is methodical and radical, but it is also temporary since the objective of this doubt is to find a truth that is undeniable. Descartes starts by making a diagnosis applied to his age. He believed the human mind was sick and needed to be freed. The cause of this disease, according to Descartes, was that humanity had taken the wrong path from the outset. Therefore, Descartes decided to submit all certainty of our knowledge to a destructive criticism.
To critique knowledge one by one would be an impossible task. Instead, methodical doubt can be applied. It directly attacks the foundations and principles of our knowledge. We must apply methodical doubt to our senses and reason.
First Meditation: Arguments of Doubt
The first meditation presents three arguments of doubt:
- The first argument questions the reliability of our senses. Descartes argues that we should not rely on our senses because they often deceive us. Examples include an oar in the water and the geocentric model of the universe.
- The second argument questions the reliability of reason. Descartes states that we can never be 100% certain of our reason.
Objections to the first argument are that there are things that no one can doubt, that our reason is very reliable, and that the senses can be reliable.
- The second argument concerns the application of methodical doubt to the distinction between sleep and wakefulness. All our experiences are representations, images that, while false, we can dream about as if they were true. Methodical doubt cannot escape our experiences.
An objection to the second argument is that mathematical proportions resist methodical doubt.
- The third argument is the argument of the evil genius (hyperbolic doubt). We must imagine that there is an evil genius that makes us believe everything is wrong. This makes doubt reach its peak. At this point, Descartes reaches the same place as the skeptics.
Second Meditation: Cogito, Ergo Sum
In the second meditation, Descartes tells us that despite everything, when we doubt, we are thinking, and thinking means that there is something that thinks. Therefore, we exist. This is Descartes’ maxim: “Cogito, ergo sum” (I think, therefore I am). For Descartes, the self consists of the soul (“res cogitans“) and the body (“res extensa“).
Objections to the first argument are that there are things that no one can doubt, that our reason is very reliable, and that the senses can be reliable.
- The second argument concerns the application of methodical doubt to the distinction between sleep and wakefulness. All our experiences are representations, images that, while false, we can dream about as if they were true. Methodical doubt cannot escape our experiences.
An objection to the second argument is that mathematical proportions resist methodical doubt.
- The third argument is the argument of the evil genius (hyperbolic doubt). We must imagine that there is an evil genius that makes us believe everything is wrong. This makes doubt reach its peak. At this point, Descartes reaches the same place as the skeptics.
Second Meditation: Cogito, Ergo Sum
In the second meditation, Descartes tells us that despite everything, when we doubt, we are thinking, and thinking means that there is something that thinks. Therefore, we exist. This is Descartes’ maxim: “Cogito, ergo sum” (I think, therefore I am). For Descartes, the self consists of the soul (“res cogitans“) and the body (“res extensa“).