Cartesian circle


Cartesian circle

The Cartesian circle is a mistake in reasoning attributed to René Descartes.

Descartes argues – for example, in the third of his "Meditations on First Philosophy" – that whatever one clearly and distinctly perceives is true: "I now seem to be able to lay it down as a general rule that whatever I perceive very clearly and distinctly is true." (AT VII 35) He goes on in the same Meditation to argue for the existence of a benevolent God, in order to defeat his skeptical argument in the first Meditation from the possibility that God be a deceiver. He then says that without his knowledge of God's existence, none of his knowledge could be certain. The argument takes this form:1) Descartes' proof of the reliability of clear and distinct perceptions takes as a premise God's existence as a non-deceiver.2) Descartes' proofs of God's existence presuppose the reliability of clear and distinct perceptions.

Descartes' contemporaries

Many commentators, both at the time that Descartes wrote and since, have argued that this involves a circle, as he relies upon the principle of clarity and distinctness to argue for the existence of God, and then claims that God is the guarantor of his clear and distinct ideas. The first person to raise this criticism was Antoine Arnauld, in the "Second Set of Objections" to the "Meditations":

"you are not yet certain of the existence of God, and you say that you are not certain of anything, and cannot know anything clearly and distinctly until you have achieved clear and certain knowledge of the existence of God. It follows from this that you do not yet clearly and distinctly know that you are a thinking thing, since, on your own admission, that knowledge depends on the clear knowledge of an existing God; and this you have not proved in the passage where you draw the conclusion that you clearly know what you are." (AT VII 124–125)

Descartes' own response to this criticism, in his "Author's Replies to the Second Set of Objections", is first to give what has become known as the Memory response; he points out that in the fifth Meditation (at AT VII 69–70) he didn't say that he needed God to guarantee the truth of his clear and distinct ideas, only to guarantee his memory:

"when I said that we can know nothing for certain until we are aware that God exists, I expressly declared that I was speaking only of knowledge of those conclusions which can be recalled when we are no longer attending to the arguments by means of which we deduced them." (AT VII 140)
Secondly, he explicitly denies that the "cogito" is an inference: "When someone says 'I am thinking, therefore I am, or I exist' he does not deduce existence from thought by means of a syllogism, but recognizes it as something self-evident by a simple intuition of the mind." (AT VII 140) Finally, he points out that the certainty of clear and distinct ideas doesn't depend upon God's guarantee; the "cogito" in particular is self-verifying, indubitable, immune to the strongest doubt.

Modern commentators

Bernard Williams presents the memory defence as follows: "When one is actually intuiting a given proposition, no doubt can be entertained. So any doubt there can be must be entertained when one is not intuiting the proposition." (p. 206) He goes on to argue: "The trouble with Descartes's system is not that it is circular; nor that there is an illegitimate relation between the proofs of God and the clear and distinct perceptions [...] The trouble is that the proofs of God are invalid and do not convince "even when they are supposedly being [intuited] ". (p. 210)

As Andrea Christofidou explains:

"The distinction appropriate here is that between "cognitio" and "scientia"; both are true and cannot be contradicted, but the latter is "objectively" true and certain (with the guarantee of God), while the former is "subjectively" true and certain, that is, time-bound, and objectively possible (and does not need the guarantee of God)." (pp 219–220)

A more interesting and more cogent defense of Descartes its against the charge of circularity is developed by Harry Frankfurt in his book Demons, Dreamers, and Madmen: the Defense of Reason in Descartes's Meditations (Bobbs-Merrill, 1970; reprinted by Princeton University Press, 2007). Frankfurt suggests that Descartes's arguments for the existence of God, and for the reliability of reason, are not intended to prove that their conclusions are true, but to show that reason leads to them. Thus, reason is validated by being shown to confirm its own validity instead of leading to a denial of its validity by being shown to be incapable of demonstrating the existence of a benevolent God.

ources and references

*René Descartes, "The Philosophical Writings of Descartes" Volume II, translated John Cottingham, Robert Stoothoff, and Dugald Murdoch (Cambridge University Press, 1984) ISBN 0-521-28808-8
*Andrea Christofidou, "Descartes' Dualism: Correcting Some Misconceptions" ("Journal of the History of Philosophy" XXXIX:2, April 2001)
*Bernard Williams, "Descartes: The Project of Pure Enquiry" (Penguin Books, 1978) ISBN 0-14-022006-2


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Cartesian circle — Allegedly circular reasoning used by René Descartes to show that whatever he perceives clearly and distinctly is true. Descartes argues that clear and distinct perception is a guarantor of truth because God, who is not a deceiver, would not allow …   Universalium

  • Cartesian circle — noun A supposed error in reasoning attributed to René Descartes. A form of circular argument …   Wiktionary

  • Cartesian circle — See method of doubt …   Philosophy dictionary

  • Cartesian doubt — Certainty series Agnosticism Belief Certainty Doubt Determinism Epistemology Estimation Fallibilism Fa …   Wikipedia

  • circle — circler, n. /serr keuhl/, n., v., circled, circling. n. 1. a closed plane curve consisting of all points at a given distance from a point within it called the center. Equation: x2 + y2 = r2. 2. the portion of a plane bounded by such a curve. 3.… …   Universalium

  • Circle — This article is about the shape and mathematical concept. For other uses, see Circle (disambiguation). Circle illustration showing a radius, a diameter, the centre and the circumference …   Wikipedia

  • Cartesian coordinate system — Illustration of a Cartesian coordinate plane. Four points are marked and labeled with their coordinates: (2, 3) in green, (−3, 1) in red, (−1.5, −2.5) in blue, and the origin (0, 0) in purple. A Cartesian coordinate system specifies each point… …   Wikipedia

  • Circumscribed circle — Circumscribed circle, C, and circumcenter, O, of a cyclic polygon, P In geometry, the circumscribed circle or circumcircle of a polygon is a circle which passes through all the vertices of the polygon. The center of this circle is called the… …   Wikipedia

  • Mohr's circle — Mohr s circles for a three dimensional state of stress Mohr s circle, named after Christian Otto Mohr, is a two dimensional graphical representation of the state of stress at a point. The abscissa, , and ordinate …   Wikipedia

  • Great circle — For fictional interstellar organization called Great Circle, see Andromeda (novel). A great circle divides the sphere in two equal hemispheres A great circle, also known as a Riemannian circle, of a sphere is the intersection of the sphere and a… …   Wikipedia


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.