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Rene Descartes (1596 - 1650)

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Modern Western Philosophy

Rene Descartes (1596 - 1650)


  • Descartes, a Frenchman, was born in Touraine in 1596.
  • He is one of the earliest and best known proponents of Rationalism, a method of understanding the world based on reason and not on senses to attain knowledge.
  • He is considered as the father of modern philosophy. But he was not only a philosopher but also a well-known mathematician.
  • Some of the names of Descartes՚ writings are:
    • Principles of Philosophy
    • Meditation of First Philosophy
    • Discourse of Method
    • Geometry
    • Passions of the Soul

Questions Raised

  • How to attain philosophical truth by the use of reason?
  • How to get that clear and distinct knowledge?

Descartes՚ Objective

  • It should be absolutely certain, self-evident and indubitable (that which can never be doubted) .
  • A system with solid foundation free from skepticism.
  • To build a system of philosophy based upon deduction which will always remain certain as geometry.

Descartes՚ Approach

  • Descartes stated to discard all that he has ever learnt from past, from philosophers or from book and to always go from the reason that we all have got as being the virtue of being a human being.
  • He stated not to believe too firmly in anything of which had been persuaded only by example or custom and convention and to always believe in things only by reason.

Four Percepts to be Followed

  • Never accept anything as true which we could not accept as obviously true.
  • Divide each of the problems in as many parts as possible.
  • Go from the simplest to the complex one.
  • Make enumerations so complete and reviews so general that we could be assured that we have not omitted anything.

Process of Doubt

  • Body, extension, motion, figure everything can be doubted.
  • Doubt everything that can be doubted in order to reach the indubitable.
  • This indubitable- is the starting point of all knowledge.
  • This is the foundation.
  • Everything else other than, I am in doubt can never be doubted. I therefore exist because I think.
  • I think therefore I am- Cogito Ergo Sum

I Exist

  • The absolutely certain, self-evident, indubitable, first principle. The only necessary truth is I think.
  • If I cease to think then at the same time I cease to be.
  • Every time I doubt, I affirm my existence.
  • I exist, as a thinking thing (mind) .
  • Therefore affirmation of the mind is the beginning of all the knowledge.
  • All that ideas we have, is known to us only by mind.
  • But, this led to the threat of solipsism, according to which only me and my mind alone exist.

The Idea of God

  • Except the idea of God all other ideas can be fictitious.
  • He is all morally good, all positive and is infinitely good.
  • I have an idea of God who is morally perfect and this idea cannot proceed from the less perfect therefore God, who is perfect must be the cause of my idea of God as a perfect substance.


Body or physical substance is independent of mind but dependent on God because only God is absolutely independent. The source of motion is God. God created matter with motion and rest. God is the prime mover.

The Thinking Substance or Mind

According to Descartes, mind is that which doubts, understands, conceives, affirms, denies, wills, refuses, Imagines and feels.

Mind-Body Relationship

  • Mind and body are opposite substances.
  • Figures and motion are modes of bodies that are extended and passive.
  • Imagination or will are modes of mind that are not extended but are active.
  • Both domains follow their own independent laws.
  • But the question arises if there is no interaction between the mind and body then I may know I am hungry, but I may not feel it. But this is not the case.

Mind and Body Interaction

  • They are combined in mind, in unity of composition.
  • The mental state neither becomes nor produces a physical state or vice versa but is troubled by it.
  • According to Descartes, there is a causal interaction.
  • Mind has its principle seat in the pineal gland. But this has been criticized a lot by the critics and for this Descartes has not given a satisfactory answer.


1. Descartes was a ________.

A. Rationalist

B. Empiricist

C. Skeptic

D. Idealist

Answer- A

Explanation-Descartes was a rationalist according to whom all knowledge depends upon the reason. Certain knowledge is a priori or reason and the goal of knowledge is certain knowledge and not something which is mere probable.

2. According to Descartes, ________ is the mode of extended substance or bodies.

A. Imagination

B. will

C. Motion

D. thinking

Answer- C

Explanation- According to Descartes, figure and motion are modes of extended substance or bodies whereas imagination and will are modes of mind.

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