PHL105Y Introduction to Philosophy Monday, December 4, 2006

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PHL105Y Introduction to Philosophy Monday,
December 4, 2006

• Wednesday is our term test. Term test review
  questions are now available on the web, along
  with a sample term test. If you can answer those
  questions, youll be ready for the test.
• There are no tutorials this Friday. Your first
  PHL 105 lecture after the break is Monday,
  January 8 your first tutorial after the break is
  Friday, January 12.
• In January, well continue reading Humes
  Enquiry. Your reading list for the whole spring
  term will be posted to the course website over
  the break.

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Two kinds of reasoning

• Deductive reasoning
• Inductive reasoning

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Two kinds of reasoning

• Deductive reasoning is concerned with the
  relations among ideas (this is the kind of
  reasoning we use in pure geometry)
• Inductive reasoning is concerned with matters of
  fact (this is the kind of reasoning we use in
  chemistry, physics, history, biology any
  science in which we have observations or
  experimental data)

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The problem of induction
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The problem of induction

• We have tasted bread in the past, and found it
  nourishing we assume that it will continue to be
  that way in the future. How?
• Past experience tells us how things were how do
  we draw conclusions about future time from that?
  How do you know it is safe to eat lunch today?

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The problem of induction

• How do we know that nature will go on the same
  way?
• (or that nature will be uniform this gets
  called the principle of the uniformity of nature
  or PUN for short)

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The problem of induction

• How do we know that nature will go on the same
  way?
• Not through pure reason (because you can conceive
  of a change in the course of nature nothing in
  the sheer ideas forces you to accept that nature
  is uniform)

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The problem of induction

• How do we know that nature will go on the same
  way?
• not through experience either! (Why not?)

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The problem of induction

• We have said that all arguments concerning
  existence are founded on the relation of cause
  and effect that our knowledge of that relation
  is derived entirely from experience and that all
  our experimental conclusions proceed upon the
  supposition, that the future will be conformable
  to the past. To endeavour, therefore, the proof
  of this last supposition by probable arguments,
  or arguments regarding existence, must be
  evidently going in a circle, and taking for
  granted, which is the very point in question.
  (23)

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The problem of induction

• We have said that all arguments concerning
  existence are founded on the relation of cause
  and effect that our knowledge of that relation
  is derived entirely from experience and that all
  our experimental conclusions proceed upon the
  supposition, that the future will be conformable
  to the past. To endeavour, therefore, the proof
  of this last supposition by probable arguments,
  or arguments regarding existence, must be
  evidently going in a circle, and taking for
  granted, which is the very point in question.
  (23)

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The problem of induction

• All arguments from experience depend on the
  principle that nature is uniform
• So dont expect an argument from experience to
  prove that nature is uniform (that would be
  circular)

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The problem of induction

• When we think there is a causal connection
  between two types of event
• (A putting my hand in the fire B feeling
  pain), we believe that events of type A will
  always (must always) be followed by events of
  type B

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The problem of induction

• When we think there is a causal connection
  between two types of event (A putting my hand in
  the fire B feeling pain), we believe that
  events of type A will ALWAYS (must always) be
  followed by events of type B
• Is it a valid objection to say that we can
  believe in that causal connection even if
  sometimes (like when Ive shot my hand full of
  Novocain) I wont feel the pain?

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The problem of induction

• When we think there is a causal connection
  between two types of event (A putting my normal
  hand in the fire B feeling pain), we believe
  that events of type A will always (must always)
  be followed by events of type B
• Is it a valid objection to say that we can
  believe in that causal connection even if
  sometimes (like when Ive shot my hand full of
  Novocain) I wont feel the pain?
• No, because in that case Im not in fact working
  with an event of type A anymore Ive changed the
  initial set-up, and I have an event of type A
  instead. Believing in causal connections means
  that every time the initial set-up is of exactly
  the same type, the same effect will result.

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The problem of induction

• So, how do we come to believe that events of type
  A will always (must always) be followed by events
  of type B?
• Again, its not through pure reason its not as
  though we could deduce from looking that the
  whiteness and softness of bread that it would
  nourish us the substances secret powers have
  nothing to do with its outward appearance

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The problem of induction

• So, how do we come to believe that events of type
  A will always (must always) be followed by events
  of type B?
• Through REPEATED experience (but how can repeated
  experience tell us something that a single
  experience could not?)

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The problem of induction

• Why does this matter?
• If there be any suspicion, that the course of
  nature may change, and that the past may be no
  rule for the future, all experience becomes
  useless, and can give rise to no inference or
  conclusion. (24)

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The problem of induction

• Hume is clear that we DO think that nature is
  uniform he just wants to know why we think that.
• My practice, you say, refutes my doubts. But
  you mistake the purport of my question. .. As an
  agent, I am quite satisfied in the point but as
  a philosopher I want to learn the foundation of
  this inference. (24)

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The problem of induction

• Is some very subtle reasoning required to learn
  that nature is uniform?
• Hume notes that the most ignorant and stupid
  peasants, nay infants, nay even brute beasts,
  improve by experience, and learn the qualities of
  natural objects, by observing the effects, which
  result from them. (25)

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The problem of induction

• Hume wants to establish that reason doesnt (and
  in fact cant) establish that nature is uniform

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The problem of induction

• Hume wants to establish that reason doesnt (and
  in fact cant) establish that nature is uniform
• Our belief in the uniformity of nature is not
  rational (although for Hume this doesnt amount
  to saying we should give it up)

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The problem of induction

• In all reasoning based on experience we assume
  the uniformity of nature. But why do we do this?
  And are we justified in doing so?

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Section V

• In which Hume proposes
• a sceptical solution
• of his doubts about our reasoning
• concerning matters of fact

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The limits of reason unaided by experience

• Hume imagines a rational adult brought suddenly
  into the world. Such a person would see a great
  succession of objects and events, but without the
  benefit of past experience would be unable to
  figure out rationally how these objects and
  events are causally related. The underlying
  causal powers joining the events never appear to
  the senses. (27)

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What it would take, to get the idea of cause

• Our rational stranger does see the secret power
  or connection directly, nor does he reason his
  way to it on the basis of what he does see.
• To reason causally as we do, he would need to
  have repeated experience of the causes and
  effects.
• But if theres nothing in a single experience to
  tip us off to the causal relation, how could
  repeated experiences do the trick?

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The solution

• What makes us infer an effect from a cause is not
  reason but custom or habit
• Repetition creates and entrenches the habit of
  moving from events of type A to events of type B
• All inferences from experience, therefore, are
  effects of custom, not of reasoning. (28)

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Custom and the idea of cause

• The sight of the flame and the idea of the pain
  Ill feel if I put my hand over it have nothing
  that connects them as ideas (this isnt like the
  triangle and 3-sidedness)
• What makes me feel that one causes the other is
  just the custom or habit I have of moving from
  one to the other (Ive gone enough times from
  flame-sightings to pain that this transition is
  very easy for me)

28
Why is this sceptical?

• In what way is Hume suggesting that we lack
  knowledge of causal relations?

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Why is this sceptical?

• In what way is Hume suggesting that we lack
  knowledge of causal relations?
• We are not detecting the presence of causal
  relations (the way we detect sweetness or
  redness), nor are we calculating that causal
  relations obtain (the way we calculate that the
  internal angles of a triangle sum to 180), based
  on what we observe

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• So far Hume has tried to explain which sorts of
  things we see as causally connected he hasnt
  explained why we believe in causes at all

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Why do we believe in causes?

• To explain why we believe in causal relations,
  Hume first needs to explain the difference
  between
• fiction (what is merely fancied or imagined) and
  belief (what we consider true)

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Fiction and belief

• What is the difference between believing
  something (say that Stephen Harper lives on
  Sussex Drive) and considering something you take
  to be fictional (say that Sherlock Holmes lives
  on Baker Street)?

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Fiction and belief

• What is the difference between believing
  something (say that Stephen Harper lives on
  Sussex Drive) and considering something you take
  to be fictional (say that Sherlock Holmes lives
  on Baker Street)?
• Hume it is a sentiment or feeling

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Distinguishing fiction and belief

• Your imagination is free to combine its original
  stock of ideas in all sorts of ways (imagine a
  horse with the head of a man!)
• If the difference between fiction and belief
  consisted in the addition of some special idea to
  all believings (absent from all fictions) then we
  could believe at will, by adding that special
  idea on to any combination of other ideas we
  could choose

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Distinguishing fiction and belief

• If the difference between fiction and belief
  consisted in the presence or absence of some
  tag idea, we could add that tag anywhere (for
  example, we could make ourselves believe that
  there really is a man-headed horse)
• We cant do that we are not free to believe at
  will (is that right?)

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Fiction and belief

• You can tell them apart because a feeling is
  attached to belief but not to fiction this
  feeling is produced naturally (like all other
  sentiments) it must arise from the particular
  situation, in which the mind is placed
• You can freely imagine the book fluttering up to
  the ceiling instead of dropping to the floor you
  cant just freely believe it will happen that way

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Fiction and belief

• Whenever any object is presented to the memory
  or senses, it immediately, by the force of
  custom, carries the imagination to conceive that
  object, which is usually conjoined to it and
  this conception is attended with a feeling or
  sentiment, different from the loose reveries of
  the fancy. In this consists the whole nature of
  belief (31)

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Fiction and belief

• belief is nothing but a more vivid, lively,
  forcible, firm, steady conception of an object,
  than what the imagination alone is ever able to
  attain. (32)

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Pre-established harmony

• Because of the way belief works, the power of
  custom over our thinking produces beliefs in
  causal transitions there is generally a nice
  parallel between the course of nature and the
  succession of our ideas
• Why would this be called a sceptical solution to
  Humes doubts about causation?