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The Cartesian Circle Qualifying Paper by Matthew Meyer
I. Introduction
Ever since the publication of his Meditations, Descartes has been accused of reasoning
in a circle. The accusation is that (1) the existence of a non-deceptive God depends on the
general veracity of clear and distinct perceptions (CDP) and that (2) the general veracity of
CDPs depends on the existence of a non-deceptive God. Since Descartes’ time, and even
more so in recent years, scholars have devoted their energies to extricating Descartes from
this predicament. In this essay, I will continue this tradition by arguing that Descartes’
reasoning is not, in fact, circular, and I will do so by developing a solution to the issue that is
by no means novel. This is because my solution will be based on Descartes’ initial attempt
to deal with the circle in the Second Set and Fourth Set of Replies.
Descartes’ solution to the circle needs to be developed because a handful of scholars
have abandoned it in the wake of the debate between Willis Doney (1955) and Harry
Frankfurt (1962).1 In his interpretation of Descartes’ solution, Doney argued that the
existence of God was necessary to secure the certainty of recalled CDPs on the grounds that
our memory might otherwise be mistaken. In his response to Doney’s article, Frankfurt
showed that such an interpretation not only leads to some unsavory consequences, such as
the infallibility of memory, but even traps Descartes in another form of circular reasoning.
While his criticisms were correct, Frankfurt did not then return to Descartes’ solution in
1 Some not-so-recent commentators who abandon Descartes’ solution for their own are Frankfurt (1968, 1970) Kenny (1968, 1970), Curley (1978), Van Cleve (1979), and Etchemendy (1981). More recent commentators who pay little or no attention to Descartes’ solution are DeRose (1992), Murdoch (1999), and Rickless (2005). Both Broughton (2002, 183ff.) and Hatfield (2003, 169ff.) discuss it, but dismiss it (however, there are parts of Hatfield’s presentation with which I am deeply sympathetic). Bennett (1990), Loeb (1992), and Della Rocca (2005) make use of the distinction between occurrent CDPs and recollected CDPs, but their projects differ from my own. Newman and Nelson (1999) also make significant use of this distinction and Descartes’ general solution, but wrongly think, like Frankfurt, that Descartes is engaged in the task of establishing, rather than assuming, a criterion for truth. My own thinking most resonates with Williams (1978).
2
search of an alternative reading. Instead, he abandoned Descartes’ solution altogether and
set out to develop his own, arguing that the Cartesian circle is not about validating memory,
but rather reason itself.2
As we shall see, there are serious problems with Frankfurt’s own attempt to solve the
Cartesian circle, and after highlighting some of these problems, I will return to Descartes,
seeking to develop a more accurate reading of his proposal. Specifically, I shall show how
Descartes’ solution to the Cartesian circle revolves around the distinction between
knowledge (scientia) and temporary certainty. Although God’s existence is necessary for
knowledge, it is not necessary for temporary certainty. This is because, for Descartes, to
know something is to be certain of it even when one is not attending to its proof. Since the
possibility of a deceptive god can cause us to doubt our CDPs when we are not attending to
their proofs, we do not have knowledge of what we have clearly and distinctly perceived. At
the same time, Descartes can prove the existence of God without falling into the trap of
circular reasoning because the proof of God does not require knowledge. Instead, all
Descartes needs is temporary certainty, and for temporary certainty, he only needs to attend
to the proof of God’s existence.
In the fourth section of the paper, I will complicate the situation a bit by discussing a
point that Descartes’ response seems to overlook, specifically his claim that it is only after
the proof of God’s existence in the Fourth Meditation that he can be sure that whatever is
clearly and distinctly perceived is true. Here, I shall show that while Descartes does not
believe at the beginning of the Third Meditation that whatever is clearly and distinctly
perceived is true, he does believe throughout the Meditations that whatever (indubitable) is certain
is true, and it is this latter claim that allows him to prove the existence of God. Indeed, I will
2 Frankfurt (1968; 1970).
3
conclude my paper by contending that while Descartes is not guilty of circular
argumentation, he nevertheless presupposes that certainty is sufficient for truth.3 What this
means, however, is that Descartes’ proofs for God’s existence and even his own only work if
there is a natural correspondence between the way we think about the world and the way the
world really is. While this shows that Descartes has failed to refute the Pyrrhonian skeptic,
i.e. one who demands a proof for a criterion of truth, I will argue, pace Newman and Nelson
(1999), that Descartes did not write his Meditations to perform such a task. Instead, the type
of skepticism he was out to defeat was one of doubt, and he believed that he could defeat this
kind of skepticism by achieving the one thing that eliminates all doubt, namely certainty.
II. Doney and Frankfurt on the Cartesian Circle
In the Second Set of Objections, Descartes’ attention is called to a potential flaw in
the argument of the Meditations. The problem to which the objector alludes is a nascent
version of what is known as the Cartesian Circle:
You [Descartes] are not yet certain of the existence of God [at the beginning of the
Third Meditation], 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 yet proved in the passage where you draw the conclusion that you clearly know
what you are. (CSM II, 89; AT VII, 124-125)
In the Fourth Set of Objections, Descartes is again confronted with the problem, where
Arnauld writes:
I have one further worry, namely how the author avoids reasoning in a circle when
he says that we are sure that what we clearly and distinctly perceive is true only
3 In some respects, I am following the “presumption in favor of the intellect” strategy that Hatfield outlines (2003, 175ff.). Bennett (1990) also makes a similar point.
4
because God exists. But we can be sure that God exists only because we clearly and
distinctly perceive this. Hence, before we can be sure that God exists, we ought to
be able to be sure that whatever we perceive clearly and evidently is true. (CSM II,
150; AT VII, 214)
Descartes responds to Arnauld by noting that he had already responded to the problem in
his Second Set of Replies. There, his answer was:
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. Now awareness of first principles
is not normally called ‘knowledge’ by dialecticians […]. 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. (CSM II, 100; AT VII, 140f.)
In his Fourth Set of Replies, he repeats his earlier answer, stating that he had made “a
distinction between what we in fact perceive clearly and what we remember having perceived
clearly on a previous occasion.” He then adds:
To begin with, we are sure that God exists because we attend to the arguments
which prove this; but subsequently it is enough for us to remember that we
perceived something clearly in order for us to be certain that it is true. This would
not be sufficient if we did not know that God exists and is not a deceiver. (CMS II,
171; AT VII, 246)
Focusing primarily on the response to Arnauld, Doney has claimed that the Cartesian circle
revolves around two propositions: (1) God exists and (2) what we clearly and distinctly
perceive is true. According to Doney, Descartes straightens the circle by distinguishing
between two senses of (2). In the first sense (2a), Descartes is saying that what he clearly
and distinctly perceives at present is true. In the second sense (2b), Descartes is saying that
what he recalls having clearly and distinctly perceived is true. While Doney claims that
5
knowledge is possible in the first case (2a) without knowing the existence of God, knowledge
in the second case (2b) requires the existence of a non-deceptive God. According to Doney,
the reason for this distinction is that recalled clear and distinct perceptions depend on
memory, whereas present clear and distinct perceptions do not. Because recalled clear and
distinct perceptions depend on memory, the meditator is faced with the possibility that an
evil genius might be playing tricks with his memory and therefore he cannot be certain that
he actually perceived something clearly and distinctly in the past. To overcome such doubts,
one must prove that there is a non-deceptive God who guarantees the validity of our memory.
As Doney writes, “memory being fallible, God must vindicate its use.”4
In identifying memory as the source of doubt, Doney maintains that reason for
Descartes is infallible.5 To make his case, he appeals to the Rules for the Direction of the Mind,
where Descartes argues that memory, not reason, is the stumbling block for anyone who
wants to attain certainty with respect to extended mathematical proofs. In the Rules,
however, Descartes does not mention the need for God to guarantee the certainty of
memory. Instead, he devises a technique for eliminating memory altogether from such
proofs. If I want to show that some proposition s follows from a series of propositions
beginning with self-evident proposition p, I only have to repeat the intermediary steps, i.e. p
entails q, q entails r, and r entails s, enough times so that I can move from p to s in one
complete train of thought. Based on his analysis of the Rules, Doney concludes that a non-
deceptive God is not necessary for knowledge of proofs that do not involve memory.
However, once the chain of reasoning becomes too long, say from p to z (as opposed to
merely from p to s), then the existence of a non-deceptive God is required to carry out the
proof.
4 Doney (1955, 326). 5 Ibid.
6
Doney’s account also explains how Descartes can move from a simple intuition like
the cogito to a more complex proof of the existence of a non-deceptive God without falling
into doubt in the face of an evil genius. On this reading, Descartes would only fall into
doubt if the proof of God were so long that it required the use of memory. However,
Doney claims that the proof of God can be performed in a “single view,” such that no
memory is involved.6 Since memory is not involved in the proof of God’s existence,
Descartes does not first presuppose the validity of memory to prove the existence of God
and then appeal to the existence of God to guarantee the validity of memory. Thus, there is
no circle.
While Doney seems to have solved the Cartesian circle by making use of Descartes’
own distinction, Frankfurt (1962) provides three reasons why Doney has missed the mark in
his analysis. To begin, Frankfurt argues that Doney’s interpretation has effectively
undermined the radical nature of Cartesian doubt. To make his point, Frankfurt quotes A.
Boyce Gibson, who claims that “the wicked genius is genuinely presented as the enemy of
the principle of reason in the universe, and not merely as a minor interloping devil playing
tricks with our memory.”7 For Frankfurt, Cartesian doubt does not affect our memory, but
rather reason itself. Next, Frankfurt claims that Doney’s interpretation commits Descartes
to the absurd doctrine that memory is infallible once the existence of a benevolent God has
been shown.8 To show that Descartes did not hold such a commitment, Frankfurt cites a
passage from the Principles of Philosophy, where Descartes writes: “What does often give rise to
error is that there are many things which we think we perceived in the past; once these
things are committed to memory, we give our assent to them just as we would if we had fully
6 Ibid. 7 Frankfurt (1962, 506). 8 Ibid.
7
perceived them, whereas in reality we never perceived them at all” (CSM I, 207; AT VIIIA,
21). Finally, Frankfurt claims that Doney’s interpretation leads to another problem of
circularity. Quite simply, if I am unsure at a given time about the reliability of a CDP, it
would be senseless to recall a past CDP of God to guarantee the reliability of my memory.
Since I cannot trust my recalled CDPs, I also cannot trust my recalled CDP of God’s
existence. Thus, I would have to perform the proof of God over again to put myself in the
appropriate state of certainty.9
Historically speaking, Frankfurt’s criticisms were decisive. Not only did other
scholars agree with Frankfurt on the issue,10 even Doney acknowledged his mistake and
developed an alternative solution to the Cartesian circle, one more in line with Frankfurt’s
own reading.11 Nevertheless, Frankfurt’s attempt to solve the Cartesian circle did not
improve the situation. This is because Frankfurt wrongly argued, or so I shall contend, that
Descartes’ project was not about validating memory, but rather reason, a point expressed in
Frankfurt’s first criticism. Specifically, Descartes’ project is about overcoming the
metaphysical doubt that something indubitable can be false.12 While I will argue against
Frankfurt’s general position in the final section of this essay, I do want to mention here one
reason for thinking that Frankfurt’s own solution is off the mark. In his own response to
the problem of circularity, Descartes neither refers to the possibility that something
indubitable might be false nor does he talk about validating reason in his own solution to the
Cartesian circle.13 Instead, what he does say is that the proof of God is necessary so that we
can be certain of CDPs even when we are not attending to them, and this is important 9 Ibid., 508. 10 See Curley (1978, 100); Van Cleve (1979, 57). 11 I follow Curley (1978, 100) here. See Doney (1970) for his revised interpretation. 12 Frankfurt (1968, 212). 13 However, there are passages elsewhere in Descartes’ corpus that do suggest he is concerned about validating reason. I will treat these passages when I argue against Frankfurt’s general position by means of a critique of Newman and Nelson (1999).
8
because Descartes thinks that we can be said to know a proposition only if we are certain of
the proposition when we are not attending to its proof. Thus, Descartes must prove the
existence of God not because he wants to secure the claim that whatever is certain is true, but
because the existence of God is a necessary condition for the possibility of knowledge
(scientia), as defined by the dialecticians.
III. An Alternative Reading of Descartes’ Solution to the Cartesian Circle
By turning away from Descartes’ solution to the Cartesian circle, Frankfurt
effectively threw out the baby with the bathwater. While Doney’s interpretation of
Descartes’ solution certainly fails, this does not entail that Descartes’ own solution fails.
This would only be the case if Doney has read Descartes correctly on this issue. However, I
do not think this is the case. In this section, I want to rescue Descartes’ baby and bring it to
maturity, and I will do so by correcting Doney’s interpretation, developing my own reading
of Descartes’ solution, and then supplementing my interpretation with passages from the
main text of the Meditations. In so doing, we will see that there is a rather straightforward
solution to the Cartesian circle, one that follows Descartes’ own views. While I will
complicate the issue in the next section, we will nevertheless see that Descartes’ solution
remains intact.
To repeat the initial stages of Doney’s interpretation, the Cartesian circle stems from
the fact that Descartes allegedly presupposes that we can know p, i.e. what we clearly and
distinctly perceive is true, only if we first know q, i.e. that God exists, and that we can know
q only if we first know p. To this, Descartes responds by distinguishing between two types
of p: the first sense of p (p1) means that what is clearly and distinctly perceived at present is
true; the second sense of p (p2) means that what is recalled as a clear and distinct perception is
true. For Doney, both p1 and p2 are productive of knowledge. The only difference is that p2,
9
as it depends on memory, requires the existence of God before it can be regarded as
knowledge, whereas p1 does not require the existence of such a God before it can be
regarded as knowledge.
This, however, is not exactly what Descartes claims. As the Second Reply makes
clear, Descartes’ desire to prove the existence of a non-deceptive God in the Third
Meditation derives from his desire to elevate the certainty he has regarding CDPs while
attending to their proofs to the status of knowledge as defined by the “dialecticians” (CSM II,
100; AT VII, 140). Present CDPs, pace Doney, do not constitute knowledge in a world in
which a deceptive god is a possibility because they are subject to doubt when one is not
attending to their proofs. For any CDP to be called knowledge, however, it must be
indubitable at all times. For a CDP to be indubitable at all times, one must be certain that a
non-deceptive God exists. Thus, God is necessary for one to have any knowledge at all.
Although an atheist can be certain of CDPs when attending to their proofs, he can never know
anything. As Descartes writes, “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 is not true knowledge, since no act of awareness that can be
rendered doubtful seems fit to be called knowledge” (CSM II, 101; AT VII, 141).
In the opening paragraphs of the Third Meditation, the distinction between being
certain of a CDP when we attend to its proof and being in a state of doubt when we do not
attend to its proof is at work in the form of what has been called Descartes’ “epistemic
schizophrenia.”14 Descartes’ epistemic schizophrenia stems from the fact that he seems to
be saying in the span of a few lines that we can and cannot doubt CDPs. To begin the
Meditation, Descartes lists “everything he knows,” the most important of which is the fact
14 Newman (2005).
10
that he is “a thing that thinks” (CSM II, 24; AT VII, 34). In the next paragraph, he re-
affirms this point: “I am certain that I am a thinking thing” (CSM II, 24; AT VII, 35).
Based on this fact, he claims that he should therefore know “what is required for my being
certain about anything” (Ibid.). At this point, however, Descartes recoils from his certainty
with respect to clear and distinct perceptions: “[a clear and distinct perception] would not
be enough to make me certain of the truth of the matter if it could ever turn out that
something which I perceived with such clarity and distinctness was false” (Ibid.). According
to Descartes, this is a real possibility, first, because some sense perceptions he thought were
certain turned out to be doubtful and, second, because he thinks that there might be a
deceptive god who could cast doubt on the most basic of mathematical truths. Descartes,
however, quickly reverses his doubt about mathematical truths, reminding himself that:
When I turn to the things themselves which I think I perceive very clearly, I am so
convinced by them that I spontaneously declare: let whoever can do so deceive me,
he will never bring it about that I am nothing, so long as I continue to think I am
something; or make it true at some future time that I have never existed, since it is
now true that I exist; or bring it about that two and three added together are more
or less than five, or anything of this kind in which I see a manifest contradiction.
(CSM II, 25; AT VII, 36)
Based on this simple summary of the beginning of the Third Meditation, one might
conclude that Descartes is simply confused about the status of CDPs with respect to their
dubitablility. However, a better reading would be that he is trying to communicate the very
distinction that he made in his response to the potentially circular nature of his project.
Specifically, the distinction at work in the opening stages of the Third Meditation is between
the indubitability of CDPs when he turns to their proofs, and the dubitability of CDPs when
he reflects on the supreme power of a god who might bring it about that he errs even in
those matters he thinks he has seen utterly clearly with the mind’s eye.
11
On this reading, the reason why Descartes’ next task is to examine “whether there is
a God, and, if there is, whether he can be a deceiver” (CSM II, 25; AT VII, 36) is because he
needs to put an end to this epistemic schizophrenia, and he can only achieve this by
eliminating the possibility that there is an evil genius who forces him to doubt CDPs when
he is not attending to their proofs. Given the distinction that Descartes makes between
temporary certainty and knowledge as defined by the dialecticians, whether Descartes begs
the question in his proof of God hinges on whether he requires knowledge of his CDPs in
order to prove the existence of God. Drawing on the arguments made above, we can say
that the only way knowledge of a CDP would be required for the proof of God would be if
the proof of God were so long that one could not attend to the entire proof. Descartes,
however, believes that this is not the case. As he writes in the Conversation with Burman, “since
our thought is able to grasp more than one item in this way, and since it does not occur
instantaneously, it is clear that we are able to grasp the proof of God’s existence in its
entirety” (CSMK, 339; AT V, 149). Thus, Descartes is able to establish the existence of God
in the Third Meditation without presupposing what the existence of God is then supposed
to secure, namely knowledge of our CDPs.
One of the dangers of arguing that we can be certain of some truths prior to proving
the existence of God is that it eliminates the epistemic benefits that a benevolent God is
supposed to bestow in the Fourth and Fifth Meditations. However, on our reading of
Descartes’ solution, God still plays a significant role in liberating the meditator from the
pangs of doubt. Indeed, we find Descartes giving voice to these pangs in the Fifth
Meditation and, in so doing, repeating the distinction between temporary certainty and
knowledge that he identifies in his Second Set of Replies. While he tells us that so long as he
perceives something very clearly and distinctly he “cannot but believe it to be true,” the
12
problem is that he “cannot fix [his] mental vision continually on the same thing, so as to
keep perceiving it clearly” (CSM II, 48; AT VII, 69). This is because other arguments would
intrude on his thinking that destroy his clear and distinct perception if he “were unaware of
God” (Ibid.). Indeed, such doubts would prevent him from having “true and certain
knowledge about anything.” Instead, he would only have “shifting and changeable
opinions.” To explain his point, he uses the same example as in the Second Set of Replies,
namely that the three angles of a triangle are equal to two right angles (CSM II, 103; AT VII,
144). So long as he attends to the proof, he “cannot but believe this to be true” (CSM II, 48;
AT VII, 70). But as soon as he turns his mind’s eye away from the proof, then in spite of
still remembering that he perceived it very clearly and distinctly, he “can easily fall into doubt
about its truth, if [he is] unaware of God” (Ibid.).
Of course, the proof of God in the Third Meditation is supposed to have liberated
the meditator from this predicament. That is, there are now no reasons, good or bad, to
doubt what he has clearly and distinctly perceived. This is a significant step in the Cartesian
project because, until this point, one could only be certain of something while one was
attending to the proof of it. What this meant was that the most one could be certain of at
any one time was a small handful of CDPs. As a result, one could never significantly
increase the number of things that one could be certain about. Gaining certainty of one
proposition by attending to its proof would likely result in the loss of certainty about another
proposition. However, once God has been perceived to exist, Descartes can now claim that
“even if I am no longer attending to the arguments which led me to judge that this is true, as
long as I remember that I clearly and distinctly perceived it, there are no counter-arguments
which can be adduced to make me doubt it, but on the contrary I have true and certain
13
knowledge of it. And I have knowledge not just of this matter, but of all matters which I
remember ever having demonstrated, in geometry and so on.” (CSM II, 48; AT VII, 70)
IV. Some Complications: The Cartesian Circle and the CD Rule
Thus far, we have argued (1) that there is a fairly simple and straightforward solution
to the Cartesian circle, (2) that Descartes provides this solution in the Second Set and the
Fourth Set of Replies, and (3) that the rudiments of this solution are already present in both
the Third and Fifth Meditations. We have also argued that one reason why Descartes’ own
solution has been overlooked by some commentators was due to Doney’s initial misreading
of Descartes’ proposal. Here, however, it must be noted that Doney’s misreading is not the
only reason why commentators have found Descartes’ solution to be somewhat dissatisfying
and why they have sought to develop more nuanced solutions to the issue. The problem has
to do with Descartes’ position on what I will call the clear and distinct rule (CD Rule).15
Descartes puts forth the CD Rule at the beginning of the Third Meditation: “So I now seem
to be able to lay it down as a general rule that whatever I perceive very clearly and distinctly
is true” (CSM II, 24; AT VII, 35). The CD Rule is important because Descartes seems to
need to know that it is true in order to prove God in the Third Meditation. The CD Rule is
problematic because Descartes tells us quite explicitly in the Synopsis that “in the Fourth
Meditation it is proved that everything we clearly and distinctly perceive is true” (CSM II, 11;
AT VII, 15).16 Hence, Descartes reasoning seems to be circular.
The best way out of this circle is to deny that Descartes requires the CD Rule in
order to prove God, and it is the best way out because it enjoys the most textual support.
Whereas Descartes tell us quite explicitly that the CD Rule is proved only after the existence
15 Loeb (1992) calls this the “truth rule.” I avoid this appellation because I believe that Descartes has another, more fundamental “truth rule” at work in the Meditations, namely that whatever is certain (indubitable) is true. 16 Also (CSM II, 9; AT VII, 13). For more, see Newman (1999).
14
of God, he never says that the CD Rule is necessary for the proof of God’s existence. Here,
some readers might object, arguing that while Descartes does not tell us explicitly that the
CD Rule is a necessary component in the proof of God, it is nevertheless necessary to know
that our CDPs are true in order to prove God. Indeed, one might argue that this is why the
CD Rule is introduced in the Third Meditation.
The problem with this line of thinking is that the CD Rule is generated from
Descartes’ own discovery that he exists and that he is a thinking thing. Thus, it must be the
case that Descartes can be certain that at least some CDPs are true without already having
proven the CD Rule. The question that therefore arises is whether the proof of God’s
existence falls within the class of perceptions of which one can be certain without already
having proven the CD Rule. As we have seen from Doney’s analysis, the proof of the
existence of God does fall within the same class of propositions as the cogito in at least one
relevant respect. Specifically, the proof of God’s existence is short enough that one can
attend to it in one continuous mental act. Therefore, just as Descartes can be certain that he
exists and that he is a thinking thing, so too can he be certain that God exists without first
proving the CD Rule.
Nevertheless, it is also the case that Descartes’ clear and distinct perception of God
differs from the cogito, and it is this difference that allows him to generate the CD rule
(although not its proof) from the latter, but not from the former. Whereas Descartes can
doubt the proposition “God exists” when he is not attending to the proof of the
proposition, he cannot, at the same time, both think of and doubt the proposition “I think, I
am.” This is because the act of doubting the proposition “I think, I am” requires calling the
proposition to mind, and once he calls this proposition to mind, he cannot doubt the
15
proposition. In this sense, a proposition such as “I think, I am” functions as its own proof.
In the Second Set of Replies, Descartes makes precisely this point:
Now some of these perceptions are so transparently clear and at the same time so
simple that we cannot ever think of them without believing them to be true. The
fact that I exist so long as I am thinking, or that what is done cannot be undone, are
examples of truths in respect of which we manifestly possess this kind of certainty.
For we cannot doubt them unless we think of them; but we cannot think of them
without at the same time believing they are true, as was supposed. Hence we cannot
doubt them without at the same time believing that they are true; that is, we can never
doubt them. (CMS II 104; AT VII 145f.)
Thus, if all CDPs were like the cogito in that one could not doubt them when one called them
to mind, the truth of the CD Rule would not require a proof of God’s existence. They
would not only be unshaken, but unshakeable.17 This is because we would be certain of
whatever CDP we called to mind, and since whatever is certain is true for Descartes, it
would be the case that all CDPs are true.
It is because Descartes is focused on a proposition like the cogito in the Third
Meditation that he first introduces the CD Rule with such confidence. Because he clearly
and distinctly perceives that he exists and is a thinking thing every time he brings the
proposition to mind, he tries to establish a general rule that whatever he clearly and distinctly
perceives is true. The problem, however, is that not all clear and distinct perceptions are
believed as soon as they are called to mind.18 That is, some CDPs can be doubted because
they can be called to mind without attending to their proofs. This is because these
17 I am indebted to Newman and Nelson (1999, 377) for this distinction. 18 As Descartes writes, “there are other truths which are perceived very clearly by our intellect so long as we attend to the arguments on which our knowledge of them depends; and we are therefore incapable of doubting them during this time. But we may forget the arguments in question and later remember simply the conclusions which were deduced from them. The question will now arise as to whether we possess the same firm and immutable conviction concerning these conclusions, when we simply recollect that they were previously deduced from quite evident principles. […] My reply is that the required certainty is indeed possessed by those whose knowledge of God enables them to understand that the intellectual faculty which he gave them cannot but tend towards the truth.” (CSM II, 104; AT VII, 146).
16
propositions do not function as their own proofs. Two examples of such propositions are
“God exists” and “the three angles of a triangle are equal to the sum of two right angles.” In
each case, one can call the proposition to mind without clearly and distinctly perceiving that
it is true. At the same time, however, once one knows the proof of the proposition, one can,
by attending to the proof, temporarily eliminate any doubts that one may have had about the
truth of the proposition, even if such doubts are caused by the possibility of an evil genius.
It is because of these CDPs that Descartes’ confidence with respect to the CD Rule
is quickly extinguished in the Third Meditation. Specifically, he realizes that, in a world in
which there might be a deceptive god, it is not the case that whatever is clearly and distinctly
perceived is necessarily true. This is because he can doubt certain CDPs, such as “the three
angles of a triangle are equal to the sum of two right angles,” when he is not attending to
their respective proofs, and because he can doubt them when he is not attending to
respective their proofs, he must consider them false, as the method adopted in the First
Meditation dictates that whatever is dubitable must be treated as false (CSM II, 12; AT VII,
18). However, when he attends to the proof of propositions such as “God exists,” he
cannot doubt the proposition, and because he cannot doubt the proposition, the
proposition, according to Descartes, must be true. While this might seem a bit odd, it is
nevertheless Descartes’ thinking on the issue, and his thinking on the issue is generated by
what I think is the fundamental premise of Descartes’ project, namely that whatever is certain
(indubitable) is true.19 Indeed, it is this premise that leads to the epistemic schizophrenia of the
19 Much has been made of the different types of certainty (psychological, metaphysical, and moral) in the literature by Gewirth (1941, 1970), Kenny (1968, 1970), Markie (1986), Curley (1993), and Della Rocca (2005). Although I believe that commentators have focused too much on these distinctions, I will nevertheless provide my own interpretation of each. While moral certainty is necessary for action (CSM I, 289; AT VIIIA, 327), both psychological and metaphysical certainty have to do with epistemic matters. Some (Gewirth, 1941) have argued that metaphysical certainty concerns truth, i.e. if I am metaphysically certain that p, then p, while psychological certainty does not. This, however, is incorrect. Instead, both psychological and metaphysical certainty have to do with truth, i.e. if I am psychologically or metaphysically certain that p, then p. The difference between
17
Third Meditation and it is this premise that creates a situation in which the same proposition
can, at one time, be true and then, at another time, be treated as if it were false.20
Nevertheless, as we have detailed above, Descartes will soon resolve the situation by
removing the possibility that there is a god who is a deceiver. Once he does, it will no longer
be possible to doubt a CDP, even when one is not attending to its proof, and because it will
no longer be possible to doubt a CDP, he will have secured the CD Rule.
V. Descartes on Certainty, Truth, and Skepticism
In the preceding sections, we have claimed that Descartes is not guilty of arguing in a
circle. That is, he is not guilty of arguing that the validity of CDPs is necessary to prove the
existence of God and arguing that the existence of God is necessary to secure the validity of
CDPs. In making our case, we have followed Descartes’ solution to the issue, distinguishing
between knowing (scientia) that a CDP is true and being certain that a CDP is true while
attending to its proof. While the former depends on the existence of God, the latter does
not, and since certainty is sufficient to prove the existence of God, Descartes is not engaged
in circular reasoning. However, we have also seen that the issue is more complicated than
Descartes might want to admit. It is more complicated because Descartes indicates that the
CD Rule, i.e. that whatever is clearly and distinctly perceived is true, is only proven in the
psychological and metaphysical certainty has to do with metaphysical doubt, i.e. the possibility of a deceptive god. If there is metaphysical doubt, then I can be psychologically certain that p, but not metaphysically certain that p. This is because to be metaphysically certain that p means to be certain that p even when I am not attending to the proof that p (hence, metaphysical certainty is equivalent to knowledge (scientia)). Because I can never be certain of anything in a world in which there is metaphysical doubt when I am not attending to a given proof, I can never have metaphysical certainty when there is metaphysical doubt. However, I can have psychological certainty in a world in which there is metaphysical doubt because I can temporarily overcome the metaphysical doubt by attending to the proof of a given proposition. Finally, while psychological certainty is not sufficient for metaphysical certainty, as metaphysical certainty requires the permanent removal of metaphysical doubt, metaphysical certainty is sufficient for psychological certainty, as metaphysical certainty is obtained when metaphysical doubt is permanently removed. In other words, once the possibility of a deceptive god is eliminated, there is no longer any distinction between metaphysical certainty and psychological certainty. 20 Admittedly, this situation is not all that odd, as Descartes is not saying that there are propositions of which we can be certain that they are both true and false at different times. Instead, what is saying is that one can be certain that a proposition is true at t1 and then be forced to treat the same proposition as if it were false at t2, not because one is certain at t2 that the proposition is false, but because the proposition is dubitable at t2.
18
Fourth Meditation, after he has proven the existence of a non-deceptive God. On this issue,
we have argued that the CD Rule is not a necessary condition for the proof of God’s
existence, as it only needs to be the case that some (not all) CDPs are true when one is
attending to their proofs. At the same time, the CD Rule is only proven in the Fourth
Meditation because the existence of a non-deceptive God is a necessary condition for the
claim that whatever is clearly and distinctly perceived is true. Again, this is because in a
world in which the evil genius is a possibility, CDPs cannot be considered true when one is
not attending to their respective proofs, and the reason why they cannot be considered true
when one is not attending to their respective proofs is because they are, at this time,
dubitable.
What these further considerations led to was not the discovery that Descartes was
guilty of circular reasoning, but rather that there was a fundamental presupposition at the
heart of the Meditations, namely that whatever is certain is true. Indeed, this premise, along
with the related demand to treat anything that is not certain as false, is so fundamental that it
forced Descartes to reject the CD Rule at the beginning of the Third Meditation. Since it
was not the case that all CDPs were certain at all times prior to the proof of God’s existence,
he could not rightfully claim that all CDPs are true. Given that certainty functions
throughout the opening stages of the Meditations as a standard for truth, we might be
tempted to convict Descartes of presupposing what he wants to prove. Such a move,
however, would be wrongheaded, and it would be wrongheaded because Descartes never
seeks to prove that whatever is certain is true. Instead, he simply presupposes it.
Indeed, this is such a fundamental presupposition in Descartes’ writings that it is
difficult to find a passage in which he explicitly states the connection. True, Descartes does
explicitly say that whatever is dubitable must be considered false at the very beginning of the
19
Meditations (CSM II, 12; AT VII, 18), but he does not then say that whatever is certain is true.
However, there are passages in Descartes’ corpus which at least imply the connection
between truth and certainty. In his response to Bourdin, Descartes writes:
When an architect wants to build a house which is stable on ground where there is a
sandy topsoil over underlying rock, or clay, or some other firm base, he begins by
digging out a set of trenches from which he removes the sand, and anything resting
on or mixed in with the sand, so that he can lay his foundations on firm soil. In the
same way, I began by taking everything that was doubtful and throwing it out, like
sand; and then, when I noticed that it is impossible to doubt that a doubting or
thinking substance exists, I took this as the bedrock on which I could lay the
foundations of my philosophy. (CSM II, 366; AT VII, 537)
While this passage has suggested to some that Descartes is interested in generating stable
beliefs and that his interest in stable beliefs is not related to his goal of attaining truth in any
controlled way,21 the most natural reading of the passage is that Descartes plans to throw out
whatever is doubtful because it might be false and accept whatever is certain as the
foundation of his philosophy because it is true. Indeed, in a passage from the Rules,
Descartes couples the quest for truth with the quest for certainty. After praising arithmetic
and geometry for being “free from any taint of falsity or uncertainty” (CSM I, 12; AT X,
364), Descartes proceeds to write: “Now the conclusion we should draw from these
considerations is not that arithmetic and geometry are the only sciences worth studying, but
rather that in seeking the right path of truth we ought to concern ourselves only with
objects which admit of as much certainty as the demonstrations of arithmetic and
geometry” (CSM I, 12f.; AT X, 366 (my emphasis)).
What these passages suggest is that Descartes’ thinking is governed by the following
two principles: (1) Whatever is dubitable must be treated as false and (2) whatever is certain
21 Bennett (1990, 75f.).
20
is true. The problem, of course, is that while we might agree with the first, we might refuse
to accept the second. The reason why we might refuse to accept the second is that certainty
seems to be a necessary but not sufficient condition for truth. In order for it to be a
sufficient condition for truth, Descartes must first show that the way we reason about the
world is the way the world really is, that there is, to use the language of Parmenides, an
identity between thinking and being. The problem for Descartes is that he cannot argue for
the truth of this claim, for this would presuppose some higher faculty or superior means by
which he could grasp the way the world really is, and if he were to introduce such a faculty,
he would again be faced with the same question, i.e. how do you know that this faculty,
unlike the senses or even reason, provides us with access to the way things are.
Fortunately, Descartes is not entirely silent on this issue, as Arnauld’s objections do
force him to address the possibility that the things we are certain about might not be true in
an absolute sense. Unfortunately, Descartes’ response is rather weak and not entirely free of
ambiguity. On this issue, Descartes writes:
First of all, as soon as we think that we conceive some truth clearly, we are naturally
inclined to believe it. And if this belief is so strong that we could not ever have any
reason for doubting the thing that we believe in this way, there is nothing further to
be looked for: we have on that matter all the certainty that can be reasonably
wished. For what does it matter to us if someone pretends that this truth of which
we are so strongly persuaded appears false to the eyes of God or the angels, and that
therefore, absolutely speaking, it is false? Why should we worry about this absolute
falsehood since we do not believe in it in the least, and have not even the slightest
suspicion of it? For we are supposing a belief or persuasion so firm that it could not
be removed; which is consequently in exactly the same situation as perfect certainty.
(CSM II, 103; AT VII, 144f.)
As the passage indicates, Descartes thinks that the denial of the identity of thinking and
being, as I have called it, would be both unintelligible and uninteresting. That is, if there
21
were, say, a second world radically different from the world that reason, in this case,
constructs, this world would not matter to us. What we really want is certainty, indeed
absolute certainty, and if it turns out that the things we are certain about are false in an absolute
sense, then we would not be worried about this in the least, not only because we would not
believe it, but because we could not believe it.
Admittedly, the claim that absolute certainty is what we ultimately desire might
sound as though Descartes is therefore unconcerned with truth.22 Such a claim, however,
would be rather striking not only because Descartes explicitly declares in the Meditations that
he is after “true and certain knowledge” (CSM II, 48; AT VII, 69),23 but also because he
entitled one of his works The Search for Truth.24 Moreover, a careful reading of the passage
shows that Descartes is not saying that he is uninterested in truth. Instead, what he is saying
is that if it were the case that those things about which we are certain were false in some
absolute sense, we would not then be concerned with absolute truth. However, as Williams
has rightly argued,25 Descartes’ language in this passage indicates that he believes it cannot be
the case that those things about which we are certain are false in an absolute sense.
Specifically, Descartes speaks of someone pretending that the things of which we have
certainty are false in an absolute sense. While Descartes believes that someone could
construct such a fantasy world, it is not something that we can take seriously. Indeed, as
Hatfield notes,26 Descartes tells us a few paragraphs later that “the evident clarity of our
perceptions does not allow us to listen to anyone who makes up this kind of story” (CSM II,
104; AT VII, 146).
22 Or as Frankfurt (1970, 179) claims, that Descartes is concerned with a coherence theory of truth rather than a correspondence theory of truth. 23 See Hatfield (2003, 173). 24 Williams (1978, 199). 25 Williams (1978, 199f.). 26 Hatfield (2003, 173)
22
While one could certainly poke holes in Descartes’ response, it is difficult to see how
he could offer a stronger defense. Indeed, demanding that Descartes prove the fundamental
claim that whatever is certain is true is not much different from demanding that one prove
the principle of non-contradiction, and as Aristotle realized long ago, one cannot use the
principle itself to prove the principle in question. Instead, one has to resort to alternative
tactics that range from showing the absurd consequences that result from denying the
principle in question to asserting, as Aristotle does, that those who refuse to accept the
principle are no better than uneducated vegetables. For Descartes, this means labeling those
who argue this way mere pretenders and showing why such a scenario would not interest us
in the slightest, even if it turned out to be true.
Because this reading will undoubtedly disappoint those, like Frankfurt, who insist
that Descartes is engaged in the project of validating reason against the skeptic, I want to
conclude this essay by stating why this reading is incorrect, and we can do this by briefly
examining a more recent and refined version of Frankfurt’s general position as put forth by
Newman and Nelson (1999). Specifically, Newman and Nelson argue that Descartes’
project is an attack on Pyrrhonian skepticism and that his attack consists of an attempt to
establish a criterion of truth.27 The problem with this reading is twofold. First, the evidence
that Descartes’ primary target in the Meditations is Pyrrhonian skepticism and the
corresponding concern for establishing a standard for truth is sparse. In their article,
Newman and Nelson cite Popkin (1979) as their source for the view that Descartes was
responding to the rise of Pyrrhonian skepticism. However, when one turns to Popkin’s
work, the evidence he presents in support of this view is rather speculative, as much of it has
to do with Descartes loosely associating with people who had dealt with the issue of
27 Newman and Nelson (1990, 370).
23
Pyrrhonian skepticism in some capacity.28 Indeed, the only substantial piece of evidence for
Descartes’ interest in skepticism comes from his reply to Bourdin, where he writes: “We
should not suppose that sceptical philosophy is extinct. It is vigorously alive today, and
almost all those who regard themselves as more intellectually gifted than others […] take
refuge in scepticism because they cannot see any alternative with greater claims to truth”
(CSM II, 374; AT VII, 548f.). While this passage is certainly enough to secure the claim that
Descartes was aware of skepticism and at least marginally concerned about its influence,29 it
is not enough to secure the claim that skepticism is Descartes’ primary target in the
Meditations.30
The second, perhaps more serious, problem with the interpretation in question is
that while we might grant that Descartes is interested in combating some form of skepticism,
there is good reason to believe that he is not interested in combating the brand of
Pyrrhonian skepticism that Newman and Nelson identify in their article. This is because
there is a significant difference between the way Descartes defines skepticism and the way
Newman and Nelson define it. For Newman and Nelson, the skepticism that Descartes is
supposed to be attacking is a skepticism which calls into question any attempt to establish a
criterion of truth. For Descartes, however, skepticism is not about establishing a criterion of
truth.31 Instead, Descartes tells us quite explicitly in his response to Bourdin and elsewhere
28 Popkin (1979, 172ff.). 29 Then again, Descartes is writing to Father Bourdin, a Jesuit, and he might be overstating his worries about skepticism precisely because Father Bourdin would presumably be worried about the skeptics, as such people are, according to Descartes, “particularly insistent in their demands for a demonstration of the existence of God and the immortality of the human mind” (CSM II, 374f.; AT VII, 549). 30 Indeed, Popkin (1979, 172) notes that Descartes’ interest in skepticism had received scant attention before him. While this speaks to Popkin’s originality, perhaps the reason why Descartes scholars had paid little attention to skepticism prior to Popkin was that Descartes was not overly concerned with it. 31 While I agree with Newman and Nelson that the so-called “defective nature” passages, where Descartes wonders whether “our nature might not be such as to make us go wrong even in matters which seemed to us utterly evident” (CSM I, 203; AT VIIIA, 16), establish grounds for doubting our non-occurrent CDPs and therefore the CD Rule as such, I do not think that these passages show that Descartes is contemplating the possibility that our defective nature might lead us to be absolutely certain about something that is absolutely
24
that “the hallmark” of skepticism is “excessive doubt” (CSM II, 375; AT VII, 549).32 Now
this difference is by no means insignificant. On the interpretation provided by Newman and
Nelson, a refutation of skepticism would consist in establishing a criterion of truth without
begging the question. As we have seen, however, Descartes does not have much to say to
someone who demands a proof for the claim that whatever is certain (indubitable) is true.
Thus, we must conclude that if this is Descartes’ project, then he has failed. However, if we
define skepticism as excessive doubt, which Descartes does, then a successful refutation of
skepticism would not be one that develops a non-question-begging strategy for establishing a
standard of truth, but rather one that conquers the most extreme forms of doubt. In other
words, a successful refutation of skepticism would be one that shows that we can, in fact, be
certain of at least some propositions. If we read Descartes’ Meditations as a project designed
to refute this kind of skepticism, and I think we should, then Descartes has achieved at least
some success, for he has, at the very minimum, shown that there is one thing that the skeptic
of this sort cannot doubt, namely his own existence.
false. That is, the purpose of these passages is to generate reasons for doubting CDPs when we are not attending to them. They do not, however, generate reasons for denying that the basic assumption of the Meditations that whatever is certain is true. Indeed, if Descartes were to deny this basic assumption, he could not even prove that there is thinking. For while he might be unable to doubt that he is doubting, his inability to doubt that he is doubting would not guarantee that he is, in fact, doubting. 32 Descartes defines skepticism in terms of doubt in six other passages (CSM I, 125; AT VI, 29), (CSM II, 94; AT VII, 130), (CSM II, 321; AT VII, 477), (CSMK, 196; AT III, 433), (CSMK, 223; AT VIIIB, 170), (CSMK, 333; AT V, 146).
25
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