Download Rene Descartes Handout #1 Historical

Rene Descartes Handout #1
Historical Framework and Meditation I
I. Crisis of Knowledge
The medieval worldview was undermined in various ways during the Renaissance,
Reformation, and Counter Reformation movements of the 16th century. The science or
wisdom of the Middle Ages was based on three sources: Aristotle, Reason, and Theology.
The reliability of each of these comes under attack in various ways in the 16th century.
Since each of these represented a kind of foundation on a pyramid structure of human
knowledge, these attacks created cracks in the foundations of the Western intellectual
tradition. They were responsible for a crisis of knowledge, what we can call an
epistemological crisis. (Epistemology is the study of knowledge; epistemological, having
to do with knowledge).
A.
The authority of Aristotle was put into question with the rise of a new science,
specifically the new physics and scientific methodology of scientists such as
Copernicus and Galileo. The critique of geocentric cosmology is an important
example of the sort of challenges put to the old science rooted in the Greek
tradition.
B.
The authority of reason was put into question with the rise of various forms of
skepticism during the Renaissance. Various skeptical arguments had existed in
Greek philosophy subsequent to Aristotle. Since the Renaissance involved a
revival of classical culture, it also brought into circulation various writings by
Greek skeptics (e.g., Sextus Empiricus). One of the Descartes' contemporaries,
Montaigne, was an important defender of skeptical arguments. One of
Montaigne's central claims was that all we could "know" are appearances, not the
real nature of things.
C.
The authority of theology was put into question with the rise of the Reformation
and its challenge against the Roman Catholic ecclesiastic authority. Also, the
Reformation itself quickly became a very diverse and pluralistic movement,
further raising doubts about whether theological ideas based on the Bible could
serve as an authority since there were so many different interpretations of the
Biblical text.
A + B + C = an epistemological crisis for the Western world. It is this crisis that
Descartes aims to resolve.
II. Certainty and Indubitability
Descartes' project was to find a secure foundation for the sciences or knowledge. His
project was not simply to fix the foundations, but to actually establish a new foundation.
He wants to examine his beliefs to see which, if any, are certain or indubitable.
A. Beliefs and Propositions
1. In philosophy the word "belief" typically refers to the cognitive act of thinking that
"something" is true. It is belief that such-and-such is (or is not) the case. The "such-andsuch" is something we can express by declarative sentences. For instance, I believe that I
teach at Saint Michael's College. In other words, I take it to be true that I teach at Saint
Michael's College. The declarative sentence "I teach at Saint Michael's College"
expresses a meaning. What I believe when I believe that I teach at Saint Michael's
College is not the sentence "I teach at Saint Michael's College," but the meaning
expressed by this sentence. This meaning can be expressed by different sentences in
different languages, but it would still believe the same thing if I believed the sentences in
a different language that also asserted "I teach at Saint Michael's College." So the object
of belief is the meaning of a declarative sentence.
2.
Philosophers call the meaning of any declarative sentence a proposition (or
statement).There are other uses of the word belief. Sometimes we use it to refer to
religious views or faith, where there may be no evidence for what is believed, or where
we don't o can't know what we believe. In other cases, we speak about belief in
something or someone to indicate trust. These will not be the uses of the term in
Descartes. It will be propositonal belief.
3. We have propositional beliefs of various sorts. There are memory beliefs (e.g., I had
eggs from breakfast yesterday). There are sensory perceptual beliefs (e.g., I see a true).
There are introspective beliefs (e.g., I seem to see a true). There are logical and
mathematical beliefs (e.g., A=A, 2 + 2 = 4). And there are many other sorts of beliefs.
Not only do we have various kinds of beliefs, we have plenty of each sort. We form new
beliefs all the time. Not all our beliefs are conscious at a given time, but they are the sort
of thing that we could become aware of fairly easily upon reflection.
B. Certainty and Indubitability
We use the word "certain" and "certainty" in various ways. Frequently it is used to refer
to the state of believing something with maximal confidence. You are certain of
something if you are sure of it. This is a kind of psychological or subjective certainty.
This is not the sort of certainty Descartes is looking for. There are many beliefs that are
psychologically certain that will not be certain in Descartes' sense. Descartes is concerned
with certainty in a more objective sense. A certain belief will have as its object a
proposition that cannot, logically or objectively speaking, be doubted. It is one for which
there are no grounds for doubt, i.e., no objective reason to suppose that it might be false.
Such a belief is also called indubitable.
We can state Descartes general line of reasoning as follows:
1. If we know some proposition p, then we are certain of p.
2. If we are certain of p, then there are no grounds for doubting p.
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3. Therefore, if we know some proposition p, then there are no grounds for doubting p.
C. Grounds for Doubt
A ground for doubt, according to Descartes, will be any possible situation that raises a
"question-mark" over the truth of a belief. And we must place a "question-mark" over any
belief is if there is a possible situation in which our holding the belief would be consistent
with the belief being false. Hence, a ground for doubt does not require proving that a
belief is false, but only showing that it could be false or need not be true. In short: in
situation Q, it is possible that <I believe p and p is false>. In such a case, it is possible
that we are mistaken. Hence, we cannot be objectively certain that p is true.
III. The Method of Doubt Examined
A.
Descartes' method of establishing a new epistemological foundation begins with
"Methodological doubt." Descartes begins with the general destruction of his
former opinions with the hope to see what opinions or beliefs can be left standing
after subjecting all his opinions to rigorous philosophical critique. Descartes
argues that methodological doubt need not require proving that beliefs are false,
but only that they are not certain or indubitable.
B.
Descartes does not aim to examine each of his beliefs individually to arrive at a
general conclusion about his beliefs. He aims to examine the sources of belief or
principles by which we learn. Call this poisoning the cognitive well. If these
sources or principles are questionable, then there will be doubt also about the
beliefs we derive from them, in much the same way that poison in a well
contaminates any water taken from the well. To raise doubts about a source of
belief, propose a possible situation that would undermine the reliability of the
source for any belief it could produce.
C.
The source of most of our beliefs is sensory experience. At any rate, nearly all our
beliefs about the external world arise directly or indirectly from sense experience.
These beliefs are may be called empirical or a posteriori beliefs. They depend on
sense experience, or at least our knowing them depends on sense experience.
Descartes also recognizes reason as a source for some knowledge (such as
mathematical knowledge and logic). What is known on the basis of reason, in
contrast to sense experience, is known a priori in contrast to a posteriori. So there
are two basic sources of belief. The goal of his methodological skepticism is to
raise doubt about the reliability each category of belief.
III. Grounds for Doubt
Each ground of doubt raises a question mark over a basic source of belief. In essence,
each argument proposes a situation in which are beliefs would not likely be true (i.e.,
situations that involve misleading evidence). The inability to eliminate these possibilities
implies that we cannot be objectively certain that our beliefs are true.
A. Grounds for Doubting Empirical or A Posteriori Beliefs
1. Hallucination/Illusion Argument
If one is having a hallucination or there is a perceptual illusion of sort some sort, then the
a posteriori beliefs formed in response to such experiences will be based on misleading
or unreliable evidence. Unless one can eliminate this possibility, the condition remains a
possibility. And thus it also remains a possibility that one believes p and p is false. Hence,
one cannot be certain of p.
But this argument is not comprehensive in scope, for although hallucinations or illusions
provide mislead us in some situations, we can always determine whether we are
hallucinating by increasing the resolution of our experience, by checking something at a
closer distance or using other senses or instruments.
2.
The Dream Argument:
Descartes' dream argument, though, is a more comprehensive sort of ground for doubting
a posteriori beliefs. If one is dreaming, then the a posteriori beliefs formed in response to
such an experience will be based on misleading or unreliable evidence. Unless one can
eliminate the possibility that one is dreaming, one cannot be objectively certain that p is
true. But Descartes' thinks that we cannot eliminate this possibility, so we are stuck with
its skeptical consequences.
We can represent Descartes' form of argument here as follows:
(P1) If I am dreaming, then the evidence I have for my a posteriori beliefs is misleading
or unreliable.
(P2) It is possible that I am dreaming.
---------------------------------------------(P3) Hence, it is possible that the evidence I have for my a posteriori beliefs is
misleading or unreliable.
From (P3) it follows that in any situation I might find myself in, I might believe some a
posteriori proposition and yet it might be false. For the possibility of dreaming entails
that however much evidence I might have for my empirical beliefs, the evidence will
always be consistent with the falsity of my belief. Hence, the possibility that I am
dreaming entails that I will always have a ground to doubt my a posteriori beliefs.
Potential problem for Descartes' dream argument
Descartes' dream argument appears at points to rest on the assumption that Descartes has
had dreams in the past and that they are so similar to our waking state that we can't really
tell them apart. The latter belief in turn presupposes a belief about there being a
distinction between our waking state and the dream state and that we can compare one to
the other to see that they are similar. These, of course, are themselves a posteriori beliefs.
But would Descartes be entitled to use these beliefs as premises in an argument that aims
to raise doubt about a posteriori beliefs. There is a potential self-defeat here.
There are several possible responses to this criticism of Descartes. Here is one. Although
Descartes may have in fact utilized such premises, it is clear that his argument need not
make these controversial assumptions at all. The argument in essence comes down to a
claim about the possibility of humans having a particular kind of experience (which he
associates with what people call dreaming) in which our experience is a misleading guide
to truths about the external world. Put this way, the argument does not depend on
Descartes believing that he has had dreams before, much less than he can tell the
difference between dream-experiences and waking-state-experiences. The argument is
purely a priori or conceptual in nature, resting only on a premise about what is possible or
non-contradictory. Surely, we could be having a kind of experience to which we normally
refer to by the word "dreaming."
B. Ground for Doubting A Priori or Conceptual Beliefs
The Evil Demon Argument:
The evil demon argument has the same general structure as the dream argument. This
time, though, the possibility under consideration is the existence of an all-powerful,
malevolent being who controls are minds and makes us have the thoughts we do. He
could control our thoughts so most of our beliefs are false, or at any rate such that all our
experiences were misleading. However, unlike the dream argument, the evil demon
argument would extend doubt even to a posteriori beliefs, such as mathematics.
Therefore, we have grounds for doubting whether any of our sensory perceptual beliefs
are true, as well as our various a priori beliefs.
(P1) If there is an all-powerful, evil demon who deceives my mind, then the evidence I
have for either my a posteriori or a priori beliefs is misleading or unreliable.
(P2) It is possible that there is an all-powerful, evil demon who deceives my mind.
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(P3) Hence, it is possible that the evidence I have for either my a posteriori or a priori
beliefs is misleading or unreliable.
Why did Descartes give this second argument? Clearly, the dream argument applies only
to a posteriori beliefs, whereas the evil demon argument applies also to a priori beliefs.
Hence, the latter argument provides a more comprehensive skeptical argument. But also,
perhaps Descartes saw certain weaknesses in his dream argument, and thus had need for
another skeptical argument. He clearly recognizes the applicability of the evil demon
argument to a posteriori beliefs.