The Cartesian Circle

Early Modern, Descartes on Method

The Circle

The problem of the circle is not, according to Van Cleve, merely Descartes’s problem. It is our problem as well, for it arises in the articulation of any suitably sophisticated epistemology. The generalized form of the problem is known as the ‘Problem of the Criterion’ and may be understood as asking the following question:

how can I know any epistemic principles unless I first know some other propositions from which to derive them? But how can I know those other propositions unless I first know some epistemic principles? (@vancleve1979, 56)

Van Cleve articulates the problem of the circle this way:

The problem of the Cartesian Circle arose for Descartes because he appeared to commit himself to each of the following propositions:

  1. I can know (be certain) that (p) whatever I perceive clearly and distinctly is true only if I first know (am certain) that (q) God exists and is not a deceiver.
  2. I can know (be certain) that (q) God exists and is not a deceiver only if I first know (am certain) that (p) whatever I perceive clearly and distinctly is true.

Obviously, if (1) and (2) are both true, I can never be certain of either p or q. (@vancleve1979, 55)

If this correctly articulate the problem of the circle then the only way out of the circle is deny either premise (1) or (2).

Denying Premise (1) — The Memory Gambit

Perhaps we can deny premise (1) by claiming that God’s guarantee is required only for the accuracy and general reliability of our memories, rather than for underwriting the reliability of clear and distinct ideas themselves. Harry Frankfurt (@frankfurt2008, ch.14) offers one set of reasons for thinking that the Memory Gambit is not part of Descartes’s strategy. But Van Cleve offers another. First, consider what Descartes says about the plight of the atheist in the second set of Objections and Replies:

The fact that an atheist can be ‘clearly aware that the three angles of a triangle are equal to two right angles” is something I do not dispute. But I maintain that this awareness of his is not true knowledge, since no act of awareness that can be rendered doubtful seems fit to be called knowledge. Now since we are supposing that this individual is an atheist, he cannot be certain that he is not being deceived on maners which seem to him to be very evident . And although this doubt may not occur to him, it can still crop up if someone else raises the point or if he looks into the matter himself. So he will never be free of this doubt until he acknowledges that God exists. (O&R 7:141; CSM 139-40)

Van Cleve argues that the above passage supports the claim that the atheist cannot rely on memory in coming to know truths via clear and distinct ideas. He puts the argument as follows:

  1. I remember clearly and distinctly perceiving p.
  2. So, I did clearly and distinctly perceive p.
  3. So, p is true.

The atheist cannot move from (a) to (c). The Memory Gambit says that the atheist cannot move from (a) to (b). Van Cleve thinks that we can reject this claim and still think that the move to (c) is problematic, since it is still an open possibility that, given (a) and (b), (c) is nevertheless false. So we need some guarantee of the move to (c), and that is where God comes in. Thus, Van Cleve concludes, Descartes cannot reject premise (1) after all.

Rejecting Premise (2)

Van Cleve examines two strategies for rejecting premise (2). 1 The first, by Alan Gewirth, attempts to show that Descartes needs God only to prove the metaphysical certainty of clear and distinct ideas, while psychological certainty consists only of an irresistible compulsion to believe, and is all that we need have prior to proving the existence of God.

Van Cleve’s primary objection is that Gewirth never gives us a means of passing from psychological certainty to metaphysical certainty.

What is added when at the end of the argument we say that God’s veracity and other things clearly and distinctly perceived are metaphysically certain? Just this: that we are psychologically certain not only of those propositions themselves, but also of the falsehood of every reason for doubting them. Thus, we have not advanced to a new kind of certainty at all. We have merely extended the class of psychological certainties. Descartes played for higher stakes. The certainty he sought was certainty in a sense entailing both maximal evidence and truth. Despite what Gewirth says, metaphysical certainty in his sense entails neither. It remains at bottom a purely psychological notion. (@vancleve1979, 60-1)

Van Cleve rejects Feldman’s strategy for similar reasons. Ultimately, Van Cleve denies that their conceptions of ‘metaphysical certainty’ are up to Descartes’s high standards (@vancleve1979, 62-3).

High Standards for Doubt

Why should we give any credence to such slight doubts as that there might be a deceiver capable of making what seems evident to one false? Here I present Van Cleve’s revised argument (@vancleve1979, 65). First, a few definitions:

Epistemic Possibliity:
if P is a proposition that S is considering at time t, then P is epistemically possible for S at t if and only if S is not certain at t of not-P
The Demon Hypothesis:
an evil demon brings it about that whatever seems evident to me is false
any manifestly evident propositions, such as 2+3=5

Van Cleve puts his argument as follows:

  1. The following proposition is epistemically possible for me: T seems evident to me and the Demon Hypothesis is true.
  2. If (P entails Q) is certain for me, and P is epistemically possible for me, then Q is epistemically possible for me.
  3. I am certain that the following entailment holds: (T seems evident to me and the Demon Hypothesis is true) entails (T is false).
  4. \(\therefore\) (T is false) is epistemically possible for me. [by (1)-(3)]
  5. \(\therefore\) I am not certain that T is true. [(4), definition]

Van Cleve makes two important points with this argument. First, that the activity of doubt presupposes the certainty of something, in this case, at least the entailment relation as described in (2). Second, one need not be certain of the truth of one’s doubts. They need merely be epistemically possible.

Finally, as Van Cleve notes, the only disputable premise in the above argument is premise (1). So one can challenge the argument only by challenging the epistemic possibility of radical doubt/the evil demon. This is equivalent to being certain that the evil demon scenario is impossible. And that is a very high standard of certainty indeed.

Van Cleve’s Solution

Van Cleve draws a distinction between two kinds of certainty, one particular, one general:

  1. For all P, if I clearly and distinctly perceive that P, then I am certain that P.

  2. I am certain that (for all P, if I clearly and distinctly perceive that P, then P). (@vancleve1979, 66-7)

The first claim (A) is particular. It says that one can be certain of a particular proposition P when one clearly and distinctly perceives it. The second claim (B) is a general claim. It says that clear and distinct perception is connected to truth, such that, whenever one clearly and distinctly perceives, then one may be certain of what one perceives.

The Plight of the Atheist

The distinction between (A) and (B) explains how Descartes thinks the theist has an advantage over the atheist without invoking the “Memory Gambit” as discussed above. Van Cleve explains:

[Descartes] concedes that even the atheist can be certain that the three angles of a triangle are equal to two right angles if he is clearly and distinctly perceiving this at the time. (A) is thus true of atheist and Descartes alike. But if at a later time both men merely remember having a clear and distinct perception of that theorem, Descartes will still be certain of it, but the atheist will not. This is not because (as the Memory Gambit would have it) Descartes can trust his memory and the atheist cannot. It is rather because Descartes can be certain (after he has proved the veracity of God) that anything he once clearly and distinctly perceived is true, whereas the atheist cannot. So (B) is true of Descartes, but not of the atheist. (@vancleve1979, 68)

Breaking Out of the Circle

If the distinction between (A) and (B) is sound then Van Cleve’s interpretation allows Descartes to straightforwardly reject premise (2) of the circle above. Recall that premise (2) says:

  1. I can know (be certain) that (q) God exists and is not a deceiver only if I first know (am certain) that (p) whatever I perceive clearly and distinctly is true.

So, according to Van Cleve, Descartes need only argue that that prior to proof of God’s existence and non-deceptive nature, the Meditator need only be certain of particular clear and vivacious ideas, not of the general principle (as articulated in (B)) that clarity and vivacity of one’s ideas is connected to (or a guarantor of) truth.

Thus, by the end of Meditation 2 the Meditator has a stock of truths which she may know for certain—viz., the cogito, and perhaps some of the particular metaphysical principles the Meditator relies on, such as the causal principle (a cause must contain at least as much reality as its effect). Van Cleve notes,

The fact that I clearly and distinctly perceive a proposition does not serve as a ground for accepting it. It is a source of knowledge, but not a ground. Nor does proposition (A) serve as a ground. Rather, it is a fact that enables knowledge to get started. (We can authenticate this fact later if we wish, but need not do so in the beginning.) (@vancleve1979, 69)

Van Cleve’s distinction between a source and a ground of knowledge is a distinction between that from which one knows (in this case the having of a C&D perception) and the reason one could cite which justifies one in thinking that one has knowledge.

This point is important for getting Descartes out of the circle. It has to be the case that (A) can be true without the Meditator’s requiring justification for believing (A)’s truth.

I maintain that in order to become certain of a proposition I do not need to know that I am clearly and distinctly perceiving it, nor that whatever I so perceive is either certain or true. It is enough that I do clearly and distinctly perceive the proposition. (A) says that this is enough. For (A) says that perceiving something clearly and distinctly is sufficient to render me certain of it…The point I have been insisting upon could be summed up as follows: (A) is not a principle I have to apply in order to gain knowledge; I need only fall under it. (@vancleve1979, 69-70)

So, from the fact that the Meditator falls under (A), and thus knows with certainty some stock of propositions (such as the cogito), she can derive (A) For all P, if I clearly and distinctly perceive that P, then I am certain that P—Van Cleve takes (A) to be equivalent to Descartes’s ‘truth rule’ (@vancleve1979, 71). Knowledge of this principle then grounds knowledge of higher-order propositions, such as that ‘I am certain that when I C&D perceive that P then P is true’, etc.

Descartes’s procedure could be summed up thus: by falling under proposition (A) (that is, the C&D Rule [or ‘truth rule’]), he becomes certain of premises from which he eventually derives proposition (A) itself. But since he does not have to use proposition (A) at any step along the way, there is no circle. (@vancleve1979, 71)

Hence, perhaps surprisingly, Descartes turns out to be a kind of epistemological externalist insofar as he thinks that our most basic beliefs admit of a warrant (viz., falling under the (A) rule) that need not be available to reflection. There is a kind of knowledge that we can attain that does not require the citation of reasons for its justification. It is thus “immediate” non-inferential knowledge. For Van Cleve’s Descartes, justification only comes in at a higher level, where one attempts to provide reasons for the kinds of epistemic principles articulated by (A) and (B).


  1. See @vancleve1979, 57-63. ↩︎

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