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Contribution of Rene Descartes to Philosophy
René Descartes (1596 - 1650) was a French philosopher, mathematician, scientist and writer of
the Age of Reason. He has been called the "Father of Modern Philosophy", and much of subsequent
Western philosophy can be seen as a response to his writings. He is responsible for one of the best-
known quotations in philosophy: "Cogito, ergo sum" ("I think, therefore I am"). His philosophy
became known as the Cartesian philosophy.
• He thought the world consisted of two kinds of substances: thinking substance (mind) and
extended substance (matter)
• He struggled with how mind and matter interacted.
• René Descartes was one of the first to claim that all we really know is what is in our own
consciousnesses, and that the whole external world is merely an idea or picture in our
minds.
Dualism
Rene Descartes is considered the father of modern philosophy because he introduced the
idea that all knowledge is the product of reasoning based on self-evident assumptions .Modern
philosophers often concerned themselves with the question of dualism. Descartes was the first to
formulate the mind-body problem in the form in which it exists today (see the section on Philosophy
of Mind), and the first to clearly identify the mind with consciousness and self-awareness, and to
distinguish this from the brain, which was the physical seat of intelligence (Dualism). In
his epistemological work in the "Discourse on the Method", he had realized that, although he could
doubt that he possessed a body, he could not under any circumstances doubt that he possessed a
mind, which led him to conclude that the mind and the body were two very different and separate
things.
His particular form of Dualism (known as Cartesian Dualism) proposed that the mind
controls the body, but that the body also influences the otherwise rational mind (such as when
people act out of passion) in a kind of two-way interaction, which he claimed, without much
evidence, occurred in the pineal gland. Gilbert Ryle later described this kind of Dualism (where

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mental activity carries on in parallel to physical action, but where their means of interaction
are unknown or, at best, speculative) as the "ghost in the machine". Although his own solution was
far from convincing, this kind of Cartesian Dualism set the agenda for philosophical discussion of
the mind-body problem for many years after Descartes' death.
Principles of Descartes
Descartes claims to have found principles that satisfy his conditions .These principles are
the following.
1. Existence of his own mind
 Descartes found he could doubt that things in front of him are really there and even that his
body exists, since he could be dreaming or hallucinating.
 However, he couldn’ t doubt that he has a mind (when he consider it attentively) because
he was doubting other things and doubting can only be done by a mind.
 It is not possible for us to doubt that, while we are doubting we exists; and…this is the
first thing which we know by philosophizing in the correct order.
 So Descartes first principle is that his own mind exists.
2. Existence of a perfect being (god)
One of Descartes arguments:
 Existence is a perfection
 So, the idea of a perfect being includes the idea of existence.
 So, a perfect being exists.
3. God created everything
Descartes argument:
 God is perfect as possible.

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 It is more perfect to have created everything that not to have done so.
 So, God created everything.
4. Whatever we clearly and distinctly perceive is true
 Descartes is here talking about perception by the mind, not the senses .He knows, and
stresses, that the senses are sometimes deceptive due to illusions, dreams, and
hallucinations.
 His argument for this principle:
 Since God created everything, he created our minds.
 So, if what we clearly and distinctly perceive to be true were false, God would be a
deceiver.
 Since God is perfect, he is not a deceiver.
 So, whatever we clearly and distinctly perceive is true.
Father of Rationalism
“Rationalism is an epistemological position in which reason is said to be the primary
source of all knowledge, superior to the senses.”
• French philosopher René Descartes, who wrote "I think therefore I am," is considered the
father of rationalism. He believed that eternal truths can only be discovered and tested
through reason.
• He was a pioneer and major figure in 17th Century Continental Rationalism (often known
as Cartesianism)
• Descartes further argued that sensory perceptions come to him involuntarily (not willed by
him), and are therefore external to his senses and therefore evidence of the existence of an
external world outside of his mind. He argued that the things in the external world
are material because God would not deceive him as to the ideas that are being transmitted,
and has given him the propensity to believe that such ideas are caused by material things.

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Because of this belief that God is benevolent and does not desire to deceive him, he can
therefore have some faith in the account of reality his senses provide him.
• Descartes dismissed the senses and perception as unreliable. Descartes concluded from this
that the senses can be misleading and that reason and deduction is the only reliable method
of attaining knowledge, which is the essence of Rationalism.
CONCLUSION
• Throughout his life, Descartes attempted to apply the rational inductive methods of science
and mathematics to philosophy.
• He also made contributions to the theory of equations.
• Descartes was the first to use the last letters of alphabet to designate unknown quantities
and the first letter to designate known quantities.
• He also invented the method for finding truth.