REN DESCARTES 15961650

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RENÉ DESCARTES 1596-1650

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DESCARTESS GOAL

• René Descartes (1596-1650) is widely regarded as
  the father of modern philosophy.
• Descartes was also a mathematician who wanted to
  make philosophy as certain as mathematics.
• Is it possible for epistemology to arrive at any
  certain knowledge? How would it go about finding
  it?

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CARTESIAN DOUBT

• Descartess method was to doubt everything which
  it is possible to doubt, to see if anything was
  beyond doubt.
• Cartesian doubt then has a goal, the goal is
  certain knowledge.
• What could be doubted could not form a legitimate
  part of epistemology. But if anything is beyond
  doubt, then at least one thing could be known for
  sure, and could form the foundation of a secure
  epistemology.

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DOUBT AND THE SENSES

• Descartes What I have accepted as most true and
  certain comes from the senses. But sometimes the
  senses are deceptive.
• Examples A stick looks bent in the water
  railroad tracks seem to come together in the
  distance water feels cold to a hand which has
  been in warm water and warm to a hand which has
  been in cold water a skyscraper looks smaller
  than it is from a distance people look like ants
  from the top of the skyscraper, etc.
• Descartes If the senses are even sometimes
  deceptive, then sense perception cannot form the
  foundation of certain knowledge.

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THE MÜLLER-LYER ILLUSION

• This is an example of a perceptual illusion. The
  line at the left looks longer, but is in fact the
  same length as the line at the right. This shows
  that seeing cannot always be trusted to give us
  the truth.

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THE RELEVANCE OF DREAMS TO CERTAIN KNOWLEDGE

• Although the senses sometimes deceive us, surely
  they do not always. Dont our senses tell us
  that we are all here in this room now listening
  to a lecture?
• Descartes says yes, we do think that based on
  sense perception. But how do we know that we are
  not dreaming that we are here listening to a
  lecture?
• Descartes . . . there are no certain
  indications by which we may clearly distinguish
  wakefulness from sleep . . .

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ARE DREAMS AND WAKING LIFE INDISTINGUISHABLE I?

• Is it possible for x to be indistinguishable from
  y, but for y to be distinguishable from x? If
  so, then a way to talk about this asymmetrical
  relation between x and y is to say that x has no
  property sufficient to distinguish it from y, but
  y has at least one property which is sufficient
  to distinguish it from x.

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ARE DREAMS AND WAKING LIFE INDISTINGUISHABLE II?

• Imagine that x is a coherent dream which, as
  coherent, is indistinguishable for the dreamer d
  from ordinary waking life (y) when d is asleep.
  When d is awake, he can distinguish his waking
  life (y) from dreaming (x) if y has some property
  which dreaming does not which is sufficient to
  make it known to d that he is awake and not
  asleep.

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ARE DREAMS AND WAKING LIFE INDISTINGUISHABLE III?

• Descartes thinks that there is nothing in waking
  life which I cannot also believe myself to feel
  when I am asleep.
• For contemporary philosophers such as Norman
  Malcolm and Anthony Kenny, this is incorrect.
  For them the difference is belief that something
  is the case, or the ability to judge that
  something is true. You can believe that you are
  in the room now, or judge that you are here now,
  but one does not have beliefs or make judgements
  during dreams.
• Descartes would say that I can dream that I am
  awake, and whereas Malcolm and Kenny would agree
  with this, they would say that to dream that you
  are awake is not to judge that you are awake.
  And if you can judge that you are awake, then you
  are awake and not asleep.

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ARE DREAMS AND WAKING LIFE INDISTINGUISHABLE IV?

• It would not seem to follow from the fact that
  the dreamer does not know that she is dreaming,
  and that dreams often seem indistinguishable from
  waking life, that waking life is not
  distinguishable from dreaming for the person who
  is awake.
• And dont dreams often have properties which
  waking life does not? For instance, they can be
  incredibly surreal and incoherent, whereas normal
  waking life is coherent and lacks the bizarre
  properties of fantastic imagery.

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CERTAINTY, SIMPLICITY, AND COMPLEXITY

• For Descartes, composite or complex things are
  less certainly known than simple things.
• And sciences such as physics, astronomy, and
  chemistry, which study complex objects are less
  certain than disciplines such as arithmetic and
  geometry which study things which are simple and
  general, and can be said of or applied to things
  whether they exist or not.
• If simple things are more certain than complex
  things, then we can approach a better
  understanding of things by breaking them down
  into their simplest parts.

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FANTASTIC ART AND COLOR

• An artist can make any number of unreal, surreal,
  or false images out of a number of shapes and
  colors. However, arent the shapes and colors
  themselves, as simple objects, real even if the
  complex object which consists of them is not?
  And arent simple colors and shapes impossible,
  or at least more difficult, to doubt than the
  fantastic images which they together compose?

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SURREALISM
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IMPRESSIONISM
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COLOR FIELD PAINTING
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GOD AND KNOWLEDGE

• 1. Descartes How do I know that God is not
  deceiving me into thinking that there is an
  external world?
• Descartes Perhaps there is no external world
  apart from my perceptions. However, arent there
  some things which dont depend on my
  consciousness? Doesnt a square have four sides,
  and 224 whether Im thinking of them or not,
  and whether I am awake or asleep?
• 2. But couldnt an omnipotent God deceive me even
  about the truths of geometry and arithmetic?
• If 1 and 2 are possible, then there is nothing
  in all that I formerly believed to be true, of
  which I cannot in some measure doubt.

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THE EVIL DEMON

• Since God is supremely good, He/She would not be
  a deceiver. Accordingly, Descartes imagines an
  evil genius who can deceive him in the matters
  previously considered.
• This is a kind of thought experiment to test
  knowledge claims.

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WHAT IS LEFT AT THE END OF DOUBT?

• Descartes Even if the external world does not
  exist, I have no body, my memories are false, and
  nothing is true which I formerly thought to be
  true, is it not at least true that I am
  something?
• If I try to persuade myself that I do not exist,
  then there is at least my self to which my
  doubting is directed.
• If there is doubt, there is a doubter who doubts.
  And this doubter must exist in order to doubt
  its own existence.

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THE DOUBTER AND THE DEMON

• Descartes I must exist for the evil deceiver to
  attempt to convince me that I do not exist.
• Descartes Let the evil demon deceive me as
  much as he will, he can never cause me to be
  nothing so long as I think that I am something.

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COGITO ERGO SUM

• Descartes I am something as long as I am
  thinking. Even if I am thinking that nothing at
  all exists at least that thinking exists.
• Descartes . . . this proposition I am, I
  exist, is necessarily true each time that I
  pronounce it, or that I mentally conceive it.
• It is necessarily true since nonexistent thinking
  is a contradiction in terms, or it is false that
  something can think which does not exist.
• Cogito ergo sum - I think, therefore I am I
  exist

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WHAT AM I? I

• My thinking guarantees that I am, but I who know
  that I am still am not sure what I am.
• What am I? What defines me essentially?
• If thinking that I might not exist ends in the
  certainty that I do exist, then thought is
  something that cannot be separated from me and
  belongs to me essentially.

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WHAT AM I? II

• I know that I exist when I think. That is
  certain. And I cant be certain that I exist
  when I am not thinking.
• My doubting guarantees that I exist as a doubter.
  Doubting is a kind of thinking or intellectual
  activity, and so my doubting everything which it
  is possible to doubt suggests that . . . I am
  not more than a thing which thinks . . . a mind
  or a soul, or an understanding, or a reason . .
  .
• What am I? A thing which thinks. At least
  this much I can know and cannot doubt.

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WHAT IS A THING THAT THINKS?

• It is a thing which doubts, understands,
  conceives, affirms, denies, wills, refuses and
  which also imagines and feels.
• Descartes is using thinking to cover mental
  phenomena in general and a being which is
  thinking through doubting, understanding,
  conceiving . . . imagining, and feeling, is a
  being which exists.
• If an event of doubting . . . imagining, or
  feeling is occurring, then there is a being which
  exists which doubts . . . imagines, or feels.
  This much is certain.

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ACTS AND OBJECTS OF EXPERIENCE

• Although I can doubt that the objects which I
  see, hear, feel and so forth really exist as they
  seem to, I cannot doubt that I am seeing,
  hearing, feeling. That is, I cannot doubt the
  experiences themselves as the experiences which
  they are.
• Such experiences constitute my mental existence
  when they occur. I then am essentially defined
  by mental operations, and these operations are
  mine and cannot be separated from myself.

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KNOWLEDGE, MIND, AND BODY

• I know of my body through perception, and the
  objects of perception may not exist. This
  includes my own body. However, it is nonsense to
  doubt the experiences themselves.
• Therefore, whereas I can doubt the existence of
  the objects to which my experiences seem to
  point, I cannot doubt the experiences themselves
  as mental experiences.
• The certainty of these mental experiences means
  that, for Descartes, the mind is more certainly
  known than the body. (We will later see that
  Richard Taylor disagrees with this, and says that
  it is the existence of bodies which are certain,
  and that it is minds which can be doubted.)

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CLEAR AND DISTINCT IDEAS I

• For Descartes, an idea is clear if its content -
  what we think about when we have that idea -
  includes the nature and essence of it.
• Thus it is of the nature and essence of a square
  to have at least four sides and at most four
  sides. And it is of the nature and essence of
  the arithmetic law which says that 224 that 2
  added to 2 cannot result in any other number.

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CLEAR AND DISTINCT IDEAS II

• An idea is distinct if nothing contradictory to
  the essence of an object is included within it.
• Thus it contradicts the essence of squareness to
  say that a square can have more or fewer than
  four sides. And it contradicts the essence of
  two added to two that it can equal a number
  greater or less than four.

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CLEAR AND DISTINCT IDEAS III

• It is easier to talk about the clarity and
  distinctness of our idea of something like a
  triangle, than it about something like our idea
  of a person. This is because it is harder to
  state the nature and essence of the idea of
  personhood. Does a being have to be conscious to
  be a person or just capable of consciousness? Is
  someone in a coma still a person even if doctors
  concur that his or her future consciousness is
  impossible? Does an entity have to be capable of
  a certain level of thought to be human? Are the
  abilities to talk and reason required? What
  about beings who are mentally handicapped, or are
  under the influence of intoxicants?

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RATIONALISM AND EMPIRICISM I

• rationalismdf. term in epistemology which holds
  that the ultimate source of knowledge is reason.
  Gould The focus of knowledge for rationalists
  is a priori knowledge. Main rationalists are
  Descartes, Spinoza, and Leibniz.
• empiricismdf. term in epistemology which holds
  that the origin of knowledge is experience alone,
  and the content of all knowledge is derived from
  experience. Gould The focus of knowledge for
  empiricists is a posteriori knowledge. Main
  empiricists are Locke, Berkeley, and Hume.

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RATIONALISM AND EMPIRICISM II

• There is not necessarily a hard division between
  empiricism and rationalism. Philosophers can see
  both knowing things through reason and knowing
  things through experience to be applicable to
  different kinds of object. For example, our
  source of knowledge of abstract objects such as
  those of logic and mathematics is reason. And
  our source of knowledge of objects in the
  external world is sense experience.

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DESCARTESS RATIONALISM I

• Descartes illustrates his rationalism through the
  example of the wax. This concerns the issue of
  the preservation of identity through change.
• Lets use an ice cube to illustrate. An ice cube
  named x which is taken at time t1 from the
  freezer is cold, hard, roughly cubic in shape,
  translucent but not transparent, can be picked
  up, carried, thrown, etc.
• At a later time t2, x has very different
  properties. It is now warm, liquid - and so
  neither hard nor cubic - transparent, cant be
  picked up, carried, or hurled across the room.
  And now it can be drunk, but before it could not.

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DESCARTESS RATIONALISM II

• Descartes would say that x is the same thing at
  t2 as at t1 - that the identity of the object
  survives the changes which it has undergone - and
  that none would judge otherwise.
• If this is true, and it is the same object x at
  t1 and t2, then the question is, how do we know
  that it is the same?
• Descartes says that it cannot be through the
  senses. This is because the sense tell us very
  different things at the two different times. If
  we went on the senses alone we would have to
  include that these are two different things.
  However, we know that they are the same thing in
  different form. How?

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DESCARTESS RATIONALISM III

• Through the mind or understanding. Descartes
  Although I cant perceive that it is the same
  object x at t1 and t2, my mind can know that it
  is the same object.
• We can only know that an object x is the same
  object x after a perceptible change as it was
  before the change by an intuition of the mind.
  This is because perception only gives evidence of
  difference, not sameness.
• To know or understand what an object is requires
  the mind. And this emphasis on the mind for
  understanding is rationalism.

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WHAT IS THE WAX (OR X)?

• Descartes Not the properties which we are aware
  of in perception, since these change while the
  wax itself remains the same.
• The wax (or our object x) which survives the
  perceptual changes is a body, distinguished from
  its external forms (those known to the senses)
  which is a certain extended thing, which is
  flexible and movable.
• This certain extended thing which underlies
  change is an object of the understanding.

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RECAPITULATION OF DESCARTESS POSITION

• Descartes would say that x cannot be identified
  with any one of its properties, such as its being
  cold or hard at t1, or its being warm or liquid
  at t2. He would also say that x cannot be
  identified with all of its properties at either
  time - all the properties it has at t1 or all the
  properties it has at t2 This is because these
  properties, as different, would constitute
  different objects. But the properties are said
  to be different properties of the same object.
• Since x cant be either any one of its properties
  at any time, or all of its different properties
  at either the earlier or later time, and yet we
  know that it is the same object, Descartes says
  that it must be the mind which recognizes x (or
  the wax) to be the same thing after change.

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AN OBJECTION THE MIND AND DIFFERENCE

• Rheinhardt Grossman points out that, if Descartes
  were correct that it is the mind which
  comprehends the identity of objects, then the
  mind ought to be able to tell whether or not
  something, such as our x at t2, is the same or a
  different object from x at t1. But this it is
  unable to do.
• Imagine that I take out x of the freezer at t1,
  leave the room, and return at t2. In the
  meantime you put x down the drain and take a
  different ice cube y from the freezer and let it
  melt. If Descartes were correct, then my mind
  ought to be able to see that y is not x at t2.

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A SECOND OBJECTION THE MIND AND SAMENESS

• Grossman points out that the mind cannot even
  tell whether two objects which have not changed,
  but which appear identical, are the same or
  different, such as two sheets of white paper. If
  Descartes were correct, then it should be
  possible for the mind to distinguish identity
  from difference in objects which are
  perceptually identical. But the mind cannot do
  this.

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THE KNOWER AND THE KNOWN I

• For Descartes, from the fact that I perceive
  something testifies to my existence. This is
  true even if that which I perceive does not
  really exist.
• Descartes . . . it cannot be that when I see,
  or . . . when I think I see, that I myself am
  nothing. I cannot be nothing since, even if the
  object which I think exists does not really
  exist, my seeing does. And if my seeing exists
  then I exist.
• Because it is false that beings other than
  existing ones can perceive, my existence follows
  from the fact that I perceive something.

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THE KNOWER AND THE KNOWN II

• For Descartes, objects are not known from the
  fact that they are perceived through sight or
  touch but only because they are understood the
  mind grasps their identity.
• And because understanding depends on a mind which
  understands . . . I see clearly that there is
  nothing easier for me to know than my mind.