Cartesian circle
Encyclopedia
The Cartesian circle is a potential 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.
, in the "Fourth Set of Objections" to the Meditations:
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 did not say that he needed God to guarantee the truth of his clear and distinct ideas, only to guarantee his memory:
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 does not depend upon God's guarantee (AT VII 145–146). The cogito
in particular is self-verifying, indubitable, immune to the strongest doubt.
presents the memory defense 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:
A more interesting defense of Descartes against the charge of circularity is developed by Harry Frankfurt in his book Demons, Dreamers, and Madmen: the Defense of Reason in Descartes' Meditations (Bobbs–Merrill, 1970; reprinted by Princeton University Press, 2007). Frankfurt suggests that Descartes' arguments for the existence of God, and for the reliability of reason, are not intended to prove that their conclusions are absolutely true, but to show that reason can be compelled to accept them, even in the face of radical sceptical arguments. In fact, according to Frankfurt, the validation of reason is accomplished by the rejection of the main sceptical hypothesis, which is the first real (albeit negative) conclusion of the argument, whilst the proposition about God's existence is a merely preparatory step.
It must be conceded that once reached the real conclusion of the argument, the cartesian method would forbid the sceptic to reply that perhaps the cartesian proof was suggested to the meditator by the evil genius itself, in the first place (thereby accusing Descartes of vicious circularity). This accusation fails, since it requires the evil genius' possible existence to be still deemed a possibility – an idea which precisely, after the expanded "God's proof" the meditator has acquired a specific reason to reject.
However, according to Frankfurt the proof presupposes the validity of the principle of non-contradiction, since otherwise an argument leading to the (provisional) conclusion that a benevolent God exists, wouldn't force Descartes to reject the possible existence of the demon. Thus the proof might, after all, beg the question against a kind of scepticism radical enough to put in doubt the rule of non-contradiction.
Moreover, according to Frankfurt's Descartes, the meditator feels forced to accept his conclusion merely because of the evidence of the supporting argument, while Frankfurt himself started by explaining that the radical doubt is meant to be a criticism of evidence as a criterion of truth (even subjective truth, if you want). As Frankfurt pointed out, it seems hard to deny that the general proposition "evident statements can be false or misleading" can be thought without hindrance, and that Descartes seems to have countenanced this kind of doubt, when close to the end of the First Meditation he wrote that
The outcome seems to be that a doubt aimed at evident ideas is supposed by Frankfurt to be overcome by means of a further evident idea, thereby begging the question. Frankfurt's ideas about the cartesian circle are further developed by Edwin Curley and Jose de Teresa.
René Descartes
René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...
.
Descartes argues – for example, in the third of his Meditations on First Philosophy
Meditations on First Philosophy
Meditations on First Philosophy is a philosophical treatise written by René Descartes and first published in 1641 . The French translation was published in 1647 as Méditations Metaphysiques...
– 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 circular argument, 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 ArnauldAntoine Arnauld
Antoine Arnauld — le Grand as contemporaries called him, to distinguish him from his father — was a French Roman Catholic theologian, philosopher, and mathematician...
, in the "Fourth 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. 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 did not 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
Syllogism
A syllogism is a kind of logical argument in which one proposition is inferred from two or more others of a certain form...
, 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 does not depend upon God's guarantee (AT VII 145–146). The cogito
Cogito ergo sum
is a philosophical Latin statement proposed by . The simple meaning of the phrase is that someone wondering whether or not they exist is, in and of itself, proof that something, an "I", exists to do the thinking — However this "I" is not the more or less permanent person we call "I"...
in particular is self-verifying, indubitable, immune to the strongest doubt.
Modern commentators
Bernard WilliamsBernard Williams
Sir Bernard Arthur Owen Williams was an English moral philosopher, described by The Times as the most brilliant and most important British moral philosopher of his time. His publications include Problems of the Self , Moral Luck , Ethics and the Limits of Philosophy , and Truth and Truthfulness...
presents the memory defense 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
Andrea Christofidou
Andrea Christofidou is Senior Lecturer in Philosophy at Keble College and Lecturer in Philosophy at Worcester College, Oxford. She has taught philosophy at the University of Oxford since 1992, and at Keble since 2001. She previously held lectureships at New College, Balliol, and Wadham College.She...
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 defense of Descartes against the charge of circularity is developed by Harry Frankfurt in his book Demons, Dreamers, and Madmen: the Defense of Reason in Descartes' Meditations (Bobbs–Merrill, 1970; reprinted by Princeton University Press, 2007). Frankfurt suggests that Descartes' arguments for the existence of God, and for the reliability of reason, are not intended to prove that their conclusions are absolutely true, but to show that reason can be compelled to accept them, even in the face of radical sceptical arguments. In fact, according to Frankfurt, the validation of reason is accomplished by the rejection of the main sceptical hypothesis, which is the first real (albeit negative) conclusion of the argument, whilst the proposition about God's existence is a merely preparatory step.
It must be conceded that once reached the real conclusion of the argument, the cartesian method would forbid the sceptic to reply that perhaps the cartesian proof was suggested to the meditator by the evil genius itself, in the first place (thereby accusing Descartes of vicious circularity). This accusation fails, since it requires the evil genius' possible existence to be still deemed a possibility – an idea which precisely, after the expanded "God's proof" the meditator has acquired a specific reason to reject.
However, according to Frankfurt the proof presupposes the validity of the principle of non-contradiction, since otherwise an argument leading to the (provisional) conclusion that a benevolent God exists, wouldn't force Descartes to reject the possible existence of the demon. Thus the proof might, after all, beg the question against a kind of scepticism radical enough to put in doubt the rule of non-contradiction.
Moreover, according to Frankfurt's Descartes, the meditator feels forced to accept his conclusion merely because of the evidence of the supporting argument, while Frankfurt himself started by explaining that the radical doubt is meant to be a criticism of evidence as a criterion of truth (even subjective truth, if you want). As Frankfurt pointed out, it seems hard to deny that the general proposition "evident statements can be false or misleading" can be thought without hindrance, and that Descartes seems to have countenanced this kind of doubt, when close to the end of the First Meditation he wrote that
"...as I sometimes think that others are in error respecting matters of which they believe themselves to possess a perfect knowledge, how do I know that I am not also deceived each time I add together two and three, or number the sides of a square, or form some judgment still more simple, if more simple indeed can be imagined?"
The outcome seems to be that a doubt aimed at evident ideas is supposed by Frankfurt to be overcome by means of a further evident idea, thereby begging the question. Frankfurt's ideas about the cartesian circle are further developed by Edwin Curley and Jose de Teresa.
Sources and references
- René DescartesRené DescartesRené Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...
, The Philosophical Writings of Descartes Volume II, translated John CottinghamJohn CottinghamJohn Cottingham is an English philosopher, educated at Merchant Taylors’ School near London, and St John’s College, Oxford. He is a Professor Emeritus of Philosophy, University of Reading, Professorial Research Fellow, Heythrop College, University of London, Honorary Fellow of St John’s College,...
, Robert Stoothoff, and Dugald Murdoch (Cambridge University Press, 1984) ISBN 0-521-28808-8 - Andrea ChristofidouAndrea ChristofidouAndrea Christofidou is Senior Lecturer in Philosophy at Keble College and Lecturer in Philosophy at Worcester College, Oxford. She has taught philosophy at the University of Oxford since 1992, and at Keble since 2001. She previously held lectureships at New College, Balliol, and Wadham College.She...
, "Descartes' Dualism: Correcting Some Misconceptions" (Journal of the History of Philosophy XXXIX:2, April 2001) - Bernard WilliamsBernard WilliamsSir Bernard Arthur Owen Williams was an English moral philosopher, described by The Times as the most brilliant and most important British moral philosopher of his time. His publications include Problems of the Self , Moral Luck , Ethics and the Limits of Philosophy , and Truth and Truthfulness...
, Descartes: The Project of Pure Enquiry (Penguin Books, 1978) ISBN 0-14-022006-2 - Edwin Curley, Descartes Against the Skeptics (Harvard University Press, 1978) ISBN 978-0674198265
- Jose de Teresa, Breve introducción al pensamiento de Descartes (UAM, Mexico City, 2007). ISBN 978-9703104642