Descartes and The Problem of Knowledge
1. I want to start with 2 things:
a) say a little about the concept of knowledge and the philosophical
position known as skepticism
b) say a little about intellectual history and the aims of Descartes' Meditations
2. Belief and Knowledge
a) If someone asked you for an example for one of your beliefs, you
might cite something deeply held such as your
belief that God exists. But to believe
something is just to assent to it or go along with it, e.g., I believe that the earth
is a sphere, that Montgomery is the capital of
Alabama, that Descartes was a Frenchman.
b) If you know something, you also believe it, but there are
things we believe but do not know.
c) What else is required? One thing is truth - If it is
not true, then you don't know it. Suppose Smith believes that Fargo
is the capital of North Dakota. He might feel
so confident about this that he exclaims, "I know that Fargo is the capital
of North Dakota!!" But he doesn't know it
because it is not in fact true. He only thinks he knows it.
d) Is knowledge = belief that is true (i.e., true belief)? To put it
another way, can someone believe a proposition that is in
fact true and yet not know it? Consider
the example of the lottery ticket that you correctly believe is a winning ticket.
This is not knowledge, but it is true belief.
e) This shows that something else is required besides true belief. What
is it?
An Example: I believe that
XXXX will not
be the next President.
Is this a true belief?
Possibly, but even if it is, I do not know it to be true. Why? Because I cannot be certain
of it.
Perhaps I can be pretty sure that this is so,
but "pretty sure" is not the same thing as being certain that it is true.
Knowledge requires certainty, and certainty is
what I do not have about this belief.
3. A tentative definition of knowledge:
S knows that P =df (i) S
believes p
(ii) p is (in fact) true
(iii) S is certain that p is true
Certainty, then, is the difference between knowledge
and true opinion. Some of our opinions are true, some aren't. But
what makes something mere opinion, as opposed to knowledge, is that it
is less than certain.
4. Another Example:
Let P = There are (say) 31 students in this room. Some ways I might be
mistaken (what some call 'skeptical hypotheses') A
skeptical hypothesis is just a story about how I could be mistaken in
believing a proposition.
a) I could have miscounted. Suppose I ask another person to count. Does
this rule out all the skeptical hypotheses?
b) Some people in the room might not be students. Suppose I check the
roll and all in the room are on my roll. Does this
rule out all skeptical hypotheses?
c) Other skeptical hypotheses: Not all on the rolls are students
[gremlins in the computer]; not all in the room are humans
[automata--see Descartes, p. 269.1].
5. It is important to understand that these examples don't prove that you can never
rule out all the skeptical hypotheses.
However, you might wonder if this is in fact the case. If you
think the answer to this question is, 'No,' then you are a
skeptic.
a) Skepticism is the doctrine that we really know nothing
at all about the world. We have many beliefs or opinions about
the world, but none of them count as knowledge
because one can never rule out all the skeptical hypotheses, which is
what we would have to do to be absolutely
certain about our beliefs.
b) Is skepticism true? Maybe it is and maybe it isn't. At this
point, we can't say. Important point: You can't just assert that
skepticism is true. You've got to provide some
reason for it. After all, we have lots and lots of beliefs and some of
them may be certain, in the sense that
all skeptical hypotheses can be ruled out. So, the skeptic owes us an argument
(or some arguments) to support his
position. This is the main purpose of the first Meditation--to investigate what
reasons (i.e., arguments) might be
offer in favor of skepticism.
6. Descartes: The Father of Modern Philosophy, notably, epistemology (1596-1650)
a) Educated by the Jesuits at La Fleche where he was accorded special
privileges such as lying in bed until noon.
b) died in Sweden in 1650; tutor to the Queen.
c) Made important discoveries in mathematics, notably he
invented analytical
geometry & the Cartesian coordinate system.
d) Had a mystical experience in November 1619 when the "Spirit of Truth,"
as he called it,
descended on him.
e) Published his most famous work the Meditations in 1641,
together with Objections and Replies.
7. Europe in the 16th & 17th century was in the throes of great intellectual ferment.
The beginning of modern science:
a) Copernicus (1473-1543) (Heliocentrism)
b) Kepler (1571-1630) (Elliptical Orbit Hypothesis)
c) Galileo (1564-1642) (Formulated Mathematically Expressed Laws of
Motion)
d) Newton (1642-1727) Also formulated mathematically expressed laws of
matter in motion, including the universal law
of gravitation.
8. To appreciate fully Descartes' contribution to the theory of knowledge, we have to
back-track a little.
a) for Medieval philosophers and theologians, to prove something, one
would cite Scriptural or other church sources for
one's views (not necessarily or exclusively the
Bible--that is a Protestant innovation). Also, after St. Thomas, citing
Aristotle as an authority was also OK.
b) Let us call this sort of epistemology authoritarian.
9. This authoritarian epistemology began to break down with the advent of the new
sciences, specifically, modern physics
and astronomy.
a) The methods employed in the new sciences were observational and
mathematical.
b) Galileo & Kepler formulated mathematically precise hypotheses
(e.g., Kepler's hypothesis that the planets moved in
elliptical orbits) which were tested against
the observed locations of the planets.
(1) Kepler's laws of planetary motion
(2) Galileo's laws of motion for bodies on
earth were tested by various experiments (e.g., rolling balls down an inclined
plane)
10. Reason and experience, then, were the touchstones for the new science. No other
authority was acceptable. No longer
was it appropriate to appeal to Scripture, writings of the
church fathers or Aristotle to prove a point. The main phil-
osophical problem this raised was to figure out the role of
reason and experience in giving us knowledge of the world.
a) This problem was to occupy philosophy for 150 years following
Descartes. One group emphasized reason as the
source of knowledge. They were
called the Rationalists
(1) Descartes
(2) Spinoza
(3) Leibniz
b) Another group of philosophers stressed experience. These were
called the Empiricists.
(1) Locke
(2) Berkeley
(3) Hume
c) A kind of grand synthesis was achieved in 1781 by the German
philosopher Kant in his Critique of Pure Reason. With
Kant the Modern Era draws to a close. The
problems with which the moderns grappled are, in one form or another,
still with us.
11. This brings us back to Descartes. Descartes' historical significance lies not so much
with the details of his theories but
with the questions he poses and the problems he raises.
a) Descartes was profoundly dissatisfied with the
"received wisdom" of his day. Unlike in mathematics, disputes seemed
endless, mistakes were common.
b) He was also greatly impressed by the new science and its
techniques.
12. Now we're ready to get to the Meditations. There is one overriding purpose in the Meditations:
A Critical Reconstruction of All Human Knowledge
To reconstruct human knowledge is to take
it apart and put it back together again. To say that it is a critical recon-
struction means that he is not going to use everything he
starts with; some things will get thrown out. But what does this
all really mean--without the metaphors? critical
reconstruction of all human knowledge involves three things:
a) Show that we really do know some things. In other words, he
wants to refute skepticism. Recall that skepticism is the
doctrine that we really don't know anything
about the world.
b) Explain how we know. This involves discovering a criterion
of knowledge, i.e., a way of distinguishing knowledge
from mere opinion.
c) Find out what we really do know. We have various beliefs
about the world, e.g.,:
(1) The sun will eventually die out.
(2) The moon is closer to the earth than the
sun.
(3) The earth is more than 1 billion years
old.
(4) This table is brown.
(5) The interior angles of a triangle add up
to 180 degrees.
(6) This is a hand.
d) Which of these things do we really know? The criterion of
knowledge will tell us. So, one of the things he wants to do
is to apply the criterion of knowledge to
discover particular claims that we can know to be true.
13. The skeptic denies that we really know any of these things. All of our beliefs
about the world are mere opinion. To refute
the skeptic Descartes must undertake his critical
reconstruction from the ground up, so to speak. At the end of his
journey, he will conclude that:
a) Some of the things we thought we knew we really don't
know.
b) Some of the things we thought we knew we really do
know.
c) There is a general criterion by which we can distinguish
(a) from (b).
14. At the end of the Meditations, Descartes claims to know:
a) He, Descartes, exists.
b) God exists.
c) Physical objects exist
d) He is a purely thinking substance and not a body.
e) Some truths of mathematics.
15. Now, if you've read the assignment, some of this might come as a bit
of a surprise. In Meditation 1 Descartes seems
to be taking the side of the skeptic--producing arguments
to show that some basic things we thought we knew are really
doubtful.
a) Part of the point here is to take one's opponent
(the skeptic) seriously and give him the best case you can. Descartes
ultimately wants to reject
skepticism, so the first thing he does is to try to construct the best and strongest case
for
skepticism that he can. Notice that
it is necessary for the skeptic to give arguments for his position. He cannot simply
assert that all of our beliefs are
mere opinion.
b) Secondly, Descartes is adopting a certain procedure
or method for finding out what we really know. The procedure
is called Methodological
Doubt. The basic idea behind this procedure is to consider beliefs and reasons for
doubting
them; if he can find some
reason for doubting them, he cannot be certain that they are true, and thus they don=t count
as knowledge. He follows this
procedure until he finds some beliefs that cannot be doubted. These will count as
knowledge an in turn
serve as the ultimate foundations for all human knowledge.
16. To see how this works in detail, let us turn to the 1st Meditation:
a) Descartes has discovered that many things he had
believed turned out to be false.
b) Although he says he is going to set aside all of his
beliefs, he doesn't actually do this.
c) Instead of considering particular beliefs, he considers
whole classes or categories of beliefs. He will mentally set
aside or suspend belief about one
of these kinds categories if and only if he can find some reason for doubting them,
however slight that reason might be
d) Two things Descartes does not do:
(1) He does not disbelieve
them. Distinguish disbelief from non-belief from suspension of belief
(2) He does not practically doubt
them (i.e. doubt them in practice) for the sake of action and getting around in
the world, Descartes accepts them. But, there remains the theoretical question:' Is
there some reason to doubt
these beliefs or are they absolutely certain? (RELATE TO EARLIER DISCUSSION OF SKEPTICAL
HYPOTHESES)
17. First Category: Beliefs based on sensory experience (the senses, generally)
a) Ground or Reason for Doubt: I've found in the
past that the senses have misled me (262.1) Examples:
(1) I thought I saw a cat on the
roof but it was a squirrel.
(2) the tower illusion
(3) bent oar in the water illusion
b) Upshot: Senses have led me astray; They are not
an indubitable starting point or foundation from which knowledge
can be rebuilt.
18. The problems alluded to above suggest that it is not all sense experience that
should be mistrusted but only sense
experience under less than ideal conditions. When our
sensory experience takes place under ideal conditions, our
sensations are what Descartes calls 'clear and evident.'
This leads us to:
Category #2 (262.1) Beliefs based on clear and
evident sensations
(1) This is a table & chair
(2) This is a hand
(3) I am seated by the fire, etc.
What ground or reason is there for doubting such beliefs? How
could I possibly be mistaken about these? Here is
where Descartes brings up some facts about his dreams.
19. What is the Dream Argument? (262, middle paragraph)
a) Let us first ask what the argument is supposed to prove.
What we're worried about are beliefs based on clear &
evident sensations. He wants to
prove that they are dubitable (i.e. there is some reason, however slight, to doubt
them)
b) The crucial premise is this: Sometimes, that I
have sensations in my dreams that are indistinguishable from the clear
and evident sensations I have when
awake. So, I can't be absolutely certain that beliefs based on these sensations
about the external world
(explain) are true.
20. More formally:
(1) Sometimes I have in my dreams clear & evident
sensations (e.g. visual sensations) which are so qualitatively similar
to those I have when
awake that the former are intrinsically indistinguishable from the latter.
(2) If (1) is true, then I might be dreaming at any time I
have clear & evident sensations.
Therefore,
(3) If I might be dreaming at any time I am having clear
& evident sensations, then no belief based on clear and evident
sensations is
indubitable.
Therefore
(4) No such belief is indubitable.
21. Why care about this argument? Well, let's ask what follows if the conclusion is true.
Recall our earlier discussion of
what knowledge is. One of the requirements for
knowledge is certainty or indubitability. To put it another way,
indubitability is a necessary condition for knowledge,
which means without indubitability there is no knowledge. This
leads us to a further argument, which can be tacked
onto the Dream Argument.
(5) If a belief is (genuine) knowledge, then it
is indubitable.
(6) No belief based on clear and evident
sensations is indubitable. (note that this just repeats premise (4), above)
Therefore,
(7) No such belief is known to be true.
This is an astonishing conclusion. Together
with the conclusion about the other category of beliefs, this means that
everything we think we know about the world
based on our sensory experience is not really known at all!! Indeed,
for all we really know, there may be no world that exists
independently of our minds. It might all be a dream or an
illusion!! This is true even if we cannot help but believe
otherwise. In other words, even if we cannot help but believe
that there is a world out there, there is no way that we
can know that there is.
22. An Objection
a) Now you might say, wait a minute! I can tell when
I'm dreaming and when I'm not for the most part. My dreams
are fuzzy and disconnected. Waking
experience is very different -- much more regularized and coherent.
b) Reply: But, Descartes might ask, how do you know
that? You believe there is this difference but can you prove it?
If you assert this, the burden of
proof is on you to give an argument for it. The real difference between clear and
evident dream sensations and clear
and evident waking sensations is that the latter but not the former correspond
to reality. But the question is,
how do we distinguish the two?
c) It's like saying it is easy to distinguish the good
stocks from the bad ones. The good stocks are going to increase in
value whereas the bad stocks will
decline in value.
d) True enough, but this does not help you distinguish the
good stocks from the bad stocks, and, equally important, it
does not imply that there are any
good stocks. They all might be bad. Explain the analogy with sensations.
e) It is important to focus on what Descartes is trying to
prove, viz., that each particular belief based on clear and
evident sensations is dubitable and
thus is not knowledge. Now it may or may not follow that the whole world is
an illusion, but that is not
what Descartes is trying to prove.
f) The bottom line is that some people have clear, vivid
and coherent dreams. Such people have, in their sensations,
nothing which is distinguishable
from waking experience.
g) When Descartes is looking at his hand, he does not
really believe that he is only dreaming that he is looking at it. He
really does believe that he is
looking at his hand. Nonetheless the dream argument shows that such beliefs are
dubitable (i.e. there is some
reason for doubt, some way he might go wrong), and that's what he is trying to show.
Descartes is playing the role of
the skeptic and skeptics only try to show that we don't know (or know for certain)
that somethings are true. They are
perfectly willing to guide their lives by mere appearance & opinion. The argument
is not about what we should
believe--here Descartes says we should follow our senses--but instead about what we
can know.
23. Descartes has now cast doubt on all beliefs based on sense experience. Thus none of
them counts as knowledge. What
other beliefs are there? Those about 'simple natures."
Read 263, 2nd paragraph.
a) What he's talking about here are simple truths of
arithmetic & geometry which do not suppose the existence of any-
thing in the world outside the
mind, e.g., '2+2+4,' 'A triangle has three sides', etc. (Note: This doesn't
presuppose the
existence of "real"
triangles, i.e., physical triangles. Ideal ones (mental constructs) will do.
b) Note also that he says these beliefs are not called into
question by the dream argument.
24. Is there any ground for doubt about this category of belief? Here he considers
how God might make him go wrong
about these beliefs (263.1)
a) For all I know, there is a God, or better yet, some evil
genius (264.1)who bends all of his efforts to deceive me,
even about those matters about
which I feel most certain.
b) I won't trot this argument out in detail. The basic
point is I believe these things, but I could be wrong, so there is a
slight chance that I am mistaken.
Therefore, these beliefs are not indubitable and thus do not count as knowledge.
25. An Objection: But, I can't doubt these things! I cannot help but believe that
1+1+2 or that the shortest distance between
2 points is a straight line. Such beliefs really are
indubitable, so there must be something wrong with the skeptical
argument here.
26. Reply:
a) We have to distinguish two senses of indubitable:
(1) A proposition P is psychologically
indubitable iff
Anyone who understands proposition p cannot help but believe it.
(2) A
proposition p is epistemically indubitable iff
There is no way a person could be mistaken in believing p.
b) A word of explanation about epistemic
indubitability: To say that a proposition is epistemically indubitable is to say
that there is no skeptical
hypothesis for that belief. Note that all the categories of belief we have examined
thusfar
have skeptical hypotheses attached
to them.
c) For an illustration of this contrast, see 271.1
d) Key point in the reply: Descartes is trying to
prove these propositions are epistemically, not psychologically certain
(i.e. indubitable). Epistemic
certainty, not psychological certainty, is what's required for knowledge.
27. Here Meditation #1 ends. Perhaps everything is epistemically dubitable. If so, the
skeptic wins. Everything we believe
might be wrong. We'd have no way of really knowing
anything!
Meditation #2
28. Meditation #2 begins where Meditation #1 leaves off: Descartes lost in a sea of doubt.
But is everything really doubtful?
a) Shortly, however, he establishes one thing as absolutely
certain: that he, Descartes, exists
b) This is the famous "cogito" passage.
Descartes is famous for saying, "I think, therefore, I am," but he doesn't
actually say this in the
Meditations, though he says it elsewhere.
c) Question: What is his proof for this?
29. The Main Idea:
a) Seems to be fairly simple & straightforward. Even if
there is a Evil Deceiver who spends all his time and effort trying
to deceive me, I can at least be
certain that I exist.
b) What is really going on here? The answer is much more
complex than it might first appear.
30. First Interpretation of the 'Cogito' Passage:
a) Let us consider the inference:
(1) I think.
Therefore,
(2) I am.
b) An immediate problem: It begs the question.
31. Second Interpretation of the Cogito Passage:
Let us interpret the passage as a kind of (valid) inference
called, 'Constructive Dilemma.'
The Argument:
(1) Either I am having deceptive thoughts (caused by an
Evil Deceiver) or I am not.
(2) If I am having deceptive thoughts (caused by an Evil
Deceiver), then I exist.
(3) If I am not having deceptive thoughts, then I exist.
Therefore,
(4) I exist.
32. The argument is valid. What about the premises?
a) (1) is obvious. The parenthetical remark just specifies
the skeptical hypothesis, which explains how I might go
wrong.
b) (2) is based on the observation that if the deceiver is
causing me to have deceptive thoughts, then I at least have
to exist to have such thoughts.
c) The idea behind (3) is that if I'm not having deceptive
thoughts and I believe that I exist, then I do in fact exist.
d) Notice that if we replace 'I exist' by say, 'I have 5
fingers' the argument fails because premise (2) isn't true. I don't
have to have five fingers in order
to be deceived. The same is true of any other statement about me (e.g., 'I have a
head.'). The statement, 'I exist'
has this special property that no skeptical hypothesis can call it into question.
33. Objections
a) Although all of the premises seem obviously true,
perhaps I am being deceived about them by the deceiver.
b) Indeed, how can I know for sure even that the argument
is valid? I said I can prove it and I can certainly write up
the steps of the proof, but if I do
that, would I really have proved the argument valid?
34. The Point: Isn't the Evil Deceiver such a powerful skeptical hypothesis that it
makes genuine knowledge impossible?
On the face of it, it seems so. But there is something
funny about my how I have represented or reconstructed
Descartes' reasoning. After all, (4) is supposed to be
known better than anything else. How could it even possibly
be proved?
a) I think the above argument misrepresents what Descartes
is up to. Note: I am about to criticize an intepretation of
Descartes I have just been
putting forth as correct.
b) I now want to suggest that he is not trying to
prove anything at all here--including the fact that he exists. To see why,
we have to back up about 1500 years
to consider the views of some ancient skeptics--views that I think Descartes
is trying to challenge here in
Meditation 2.
35. The ancient skeptics, notably Pyrrho, argued that no one could ever prove anything.
Here's why:
Insert Diagram From Class Here
Either the process goes on infinitely far
and thus is never completed or it begins at some arbitrary starting point.
(arbitrary=no reason for). If some premise somewhere up
this chain of reasoning arbitrary, then anything that depends
on it is also groundless.
a) If this argument succeeds, all proof is impossible. If knowledge requires proof, then all knowledge is impossible as well.
36. Let us suppose that Descartes was aware of this challenge. One way of looking at what
he is doing at the beginning of
Meditation #2 is to try to meet this challenge. How so?
a) He is explaining why the 'I exist' is not an
arbitrary starting point even though no argument can be offered in support
of it. Why?
b) Because it is indubitable-- epistemically
indubitble.
37. And its indubitability consists in the fact that no one can be mistaken in believing
it. There are no skeptical hypotheses
or potential explanations of how he could go wrong.
Any such explanation presupposes the 'I exist'
a) To summarize: He's not trying to prove his
existence - only explain its indubitability. This blocks the ancient
skeptic's argument.
38. What follows this is Descartes' attempt to prove that he is a thing that thinks, i.e.
that his essence is thought. We'll
not discuss this argument.
39. Other topics in Meditation #2
a) Descartes' knowledge of his own mental states
b) The wax passage
40. Descartes goes to great lengths to show that his knowledge of himself
& his existence is not sensory or by way of
what he calls his imagination.
41. However, certainty does attach to knowledge of my own mental states (p. 267.2)
This is extremely important.
a) Here we have, in outline, the problem of our knowledge
of the external world.
b) Incorrigibility as the mark of the mental
c) knowledge of mental states is epistemically privileged
42. The wax passage:
a) He's not even established that he knows that bodies
exist, but for the sake of discussion, he'll assume that he does.
b) The question: Assuming we do have knowledge of
the wax, what is the essence of the wax?
c) Descartes' answer: Not any of its sensible
qualities. Rather, its essence is extension (=filling up space)
d) Conclusions:
(1) The essence of
material objects is extension
(2) Our knowledge of
material objects is not through the senses but through the intellect.
(3) Knowledge of things
is knowledge of their essences.
43. The Problem of Other Minds
a) p. 269, at the top.
b) Not just a philosopher's puzzle - there are legitimate
questions about whether computers and animals think.
c) Descartes also raises the question here, which is also
raised by the wax passage, about what it is that we actually
see as opposed to what we judge
(interpret). This suggests the possibility that the mind is much more active in
perception than one might think.
This is something later philosophers and psychologists have picked up on.
44. Next, I want to do three things:
a) Explain why Descartes wants to prove the existence of
God.
b) Explain what is going on in Meditations #3 & #4.
c) Explain a major problem with what Descartes is doing,
which is commonly known as ‘the Cartesian Circle.'
45. At the beginning of Meditation #3, Descartes returns to what he knows with
certainty--his ideas & his existence--and
he asks what assures him of the truth of these
propositions.
a) His answer: the clarity and distinctness of the ideas.
On this basis, Descartes adopts the general
rule:
"Whatever I clearly and distinctly conceive of is true."
b) Read the last sentence of the second paragraph of
Meditation 3.
46. What's next: The 1st order of business is to prove that the Evil Deceiver
hypothesis is false. Remember, the possibility
that there is such a being, which was first brought
up in Meditation #1, has not been dealt with.
a) Now, according to Descartes, this amounts to
proving the existence of an all-perfect God. Here's why: If God
exists and is all-good
(which, by definition, He is), then He could not allow such a being to work his tricks on
poor Descartes.
God, would, in effect, be colluding in the deception that the deceiver practices and thus
would
himself be a
deceiver. So, if Descartes can prove that God does exist and is no deceiver,
then he will be able to
reject the Evil
Deceiver hypothesis.
b) Here's another way to make this point: What
Descartes is worried about is the possibility of being deceived
about psychologically
indubitable propositions. Recall that these are the ones he and every other mind cannot
help but believe. There
is something about the propositions themselves that compels assent.
c) How can he show that he can't go wrong in
believing such propositions? Answer: Prove that there is an all-per-
fect God.
d) Reason: If Descartes were to go wrong
in believing these propositions--proposition he and all other finite minds
cannot help but
believe, then God would be implicated, in effect God would be a deceiver.
e) So, the idea is that if there is an
all-perfect God, then we could not be mistaken about these propositions. That's why
Descartes wants to prove the existence of God.
47. The bulk of Meditation 3 is taken up with a proof of the existence of God. Meditation
4 tries to explain how, despite
the fact that an all-perfect God exists, error and false
belief are nonetheless possible.
a) We're going to skip the details of this
argument.
b) The basic idea is this: Descartes tries to
prove, from the fact that he has an idea of God, that God must
exist in
reality. Now, in general, one cannot do this; from the mere fact that someone has an
idea of something,
it does not follow that
this thing exists in reality, since we can readily think of things that do not exist. But,
claims
Descartes, the idea of God
is different. We are thinking about an all-perfect being, which by definition, has the
highest possible degree
of reality. Since there has to be "as much" reality in the cause as there is in
the effect," it
follows that there
would have to exist an infinitely real being to cause my idea of God. Since only God can
be
infinitely real, God exists
in reality. Now this argument both obscure and unconvincing, but for our purposes, it is
not necessary to grasp the
details of this argument or the problems with it. Descartes has another, much better
argument for the existence
of God in Meditation 5. What I would like you to assume is that he has succeeded in
proving the existence of
God.
48. For now, let us return to the main thread of Meditation #3. Before proving the
existence of God, Descartes investigates
the nature of his ideas and potential sources of error.
a) ideas, considered in and of themselves are neither true nor
false
b) some ideas, or to be less misleading, mental events, are
volitions or feelings, and they can be neither true nor false.
c) Only judgments have this property --capability of being true
or false, possibility of being in error.
49. Where do ideas come from?
a) Some seem to have been born with me
b) Some seem to come from me
c) Some seem to come from without--that is, from
something "outside" of me.
50. Descartes further notes that he believes that his ideas of things represent and
resemble those things (37.1). That is, he
believes in Indirect Representative Realism:
What is directly presented to the mind are its ideas and the contents
of
one's ideas resemble objects existing in a world external to
one's mind.
a) Contrast this view with Naive Realism, which holds that the
mind is directly acquainted with "external" objects.
b) Now Descartes will later argue in detail that Indirect
Representative Realism is true, but for now he will consider
and reject two quick arguments to
establish it.
50. Two reasons:
a) nature teaches me so (practical life)
b) some of my ideas are not dependent on my will
51. Descartes rejects both of these arguments:
a) Sometimes natural inclination leads me astray
b) A hidden faculty (dream argument)
52. Descartes' conclusion about Indirect Representative Realism is given at the top of
p. 273. Indirect Representative
Realism has not been established and the problem of our
knowledge of the external world has not been solved. It is
at this juncture that he begins his argument for the
existence of God alluded to above.
53. Meditation 4: In Meditation #4, Descartes investigates the nature of error and
explains how it is possible for an
all-perfect God to exist and for Descartes to make
mistakes.
a) He wants to prove that God is no deceiver to banish the
Evil Deceiver hypothesis because until that is done, he
cannot be absolutely certain that
the psychologically indubitable propositions are in fact true.
b) The argument for, 'God is no deceiver' goes as follows
(last sentence of the 1st paragraph on 276; all of the
second paragraph on that
page):
(1) Deception is an imperfection.
(2) God has no imperfections.
Therefore,
(3) God is no deceiver.
c) Yet he must explain how it is possible for him to be deceived about
some things. This takes up most of Meditation 4
and he gives something analogous to the Free
Will Defense in The Problem of Evil. We can skip the details of this
discussion.
54. The Cartesian Circle: First Statement:
a) Arnauld raises the following objection:
Descartes claims that we can be
certain and thus know that God exists because we can know each of the steps in
the proof that leads to the
conclusion - God exists. For each step in the proof, says Descartes, we have a clear and
distinct idea and thus we are
following his general principle stated at the beginning of Meditation #3.
EVERYTHING I CLEARLY AND DISTINCTLY CONCEIVE OF IS TRUE
b) But God's existence is proved to show that the Evil
Deceiver hypothesis is not a genuine possibility. But why do that?
c) Because if that were a genuine possibility, then
Descartes could be mistaken about anything, including things he clearly
and distinctly conceives of.
Indeed, he makes this very point in what I call 'The Startling Admission':
". . . . I must examine whether there is a God and if there is, whether he can be a
deceiver.
For if I do not know this, it seems that I can never be quite certain about anything
else."
(end of paragraph 1, p. 271)
It is not clear if Descartes
meant the scope of this doubt to include the "I exist" and statements about the
contents of
his consciousness. Although it
doesn't matter, let us suppose they are not included. However, the general principle,
"Whatever I clearly and
distinctly conceive of is true,' would surely be open to question until the existence of a
non-deceiving God has been proved.
d) One way of framing the problem is that Descartes' proof
for the existence of God relies on clear and distinct ideas,
which are themselves open to doubt
until he has actually proved the existence of God. So, his argument for the
existence of God begs the question
at issue. Indeed, it would seem that any argument for the existence of God
(at this point in the Mediations)
would have this problem. To put it another way, until he proves the existence of a
non-deceiving God, he is in no
position to rely on his clear and distinct ideas. But, of course, that is just what he
has done in the series of arguments
or proofs leading to the conclusion that there is a non-deceiving God.
55. The Cartesian Circle: Second Statement
a) It gets worse. Why does Descartes want to prove the
existence of a non-deceiving God? Because this would validate
the psychologically indubitable
propositions, which have been left hanging since Meditation 1. And some other things
as well.
b) To see what these other things are, let us look at how
he finally solves the problem of our knowledge of the external
world in Meditation 6. See 284.1.
The basic idea is that he can know that there is a material world beyond our
senses because God would be a
deceiver if there weren't such a world.
c) But that means that the failure to give a
non-question-begging argument for the existence of a non-deceiving God
means that he has failed to solve
the problem of our knowledge of the external world! And indeed that is the really
momentous problem that goes under
the heading of the Cartesian Circle.
d) And it is hard to see how this problem could be solved.
e) That's the ultimate problem of the Cartesian Circle.
f) To see how Descartes might get out of this problem, it
is necessary to take my Philosophy 241 course!
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