David Hume

1
David Humes Skepticism

• The nature of ideas and reasoning concerning
  matters of fact

2
David Hume 1711-1776

• Prolific and successful writer on philosophy,
  history and economics published his Treatise at
  the age of 26.
• Never held a university position (he was
  suspected of atheism).
• The French called him le bon David.

3
Empiricism

• Hume is called an empiricist, because of the
  emphasis he and his fellow empiricists placed on
  the contribution of experience to our knowledge.
• Descartes is called a rationalist he and his
  fellow rationalists emphasized the importance of
  fundamental principles of thought that he regards
  as a priori, that is, as knowable independent of
  experience.

4
The source of ideas

• For Hume ideas are merely faint images or copies
  of much more vivid experiences perceptions of
  the senses and emotional states.
• This difference in liveliness (force or
  vivacity) is the real difference between the
  weaker states of mind we call ideas and other
  perceptions of the mind, which Hume proposes to
  call impressions.

5
The imagination

• According to Hume we can freely combine our ideas
  in almost unlimited ways.
• But the basic materials that we combine and
  rearrange so freely depend strictly on
  experience, i.e. on having previously had an
  impression, of which our idea is a kind of pale,
  weak copy.
• Consider the contrast between Humes account of
  the idea of God and Descartes.

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Arguing for the view

• If you disagree, says Hume, give me an example of
  an idea that doesnt depend on experience in this
  way!
• We find, whenever someone lacks a sense (sight,
  e.g.) or the opportunity to experience something
  (the dry Laplander, the mild mannered man), they
  also lack the corresponding ideas.

7
One contrary case

• The missing colour
• Given a complete sequence of shades with one gap
  where a shade is omitted, we seem able to imagine
  what that shade is like, i.e. to form the idea of
  that shade.
• Hume thinks this exception is so singular that
  the general principle should be retained.
• What allows this to happen? Can we think of any
  other such cases?

8
A method for inquiry

• Since impressions are always more lively and
  clear, when we try to think about any idea (or
  the meaning of any philosophical term), we should
  always try to trace it back to the impression
  from which it is derived.
• If we cant do this, we are justified in
  suspecting that the term is employed without any
  meaning or idea.

9
Operations of the Understanding

• Relations of ideas
• Geometry, Algebra, Arithmetic
• Affirmations that are intuitively or
  demonstratively certain.
• Matters of Fact
• The contrary of these is possible.
• Cant demonstrate such facts (otherwise their
  contraries would be contradictions and could
  never be distinctly conceived by the mind).

10
The Sun

• The Sun will not rise tomorrow.
• Though were sure this is false, we cant
  demonstrate that it is (to do so requires showing
  that its somehow contradictory, but it isnt we
  can distinctly conceive this happening).
• So we have a puzzle (W)hat is the nature of
  that evidence which assures us of any real
  existence and matter of fact beyond the present
  testimony of our senses or the records of our
  memory?

11
Cause and Effect

• The basis of all reasoning concerning matters of
  fact.
• This is the link that connects any present or
  remembered facts to other facts that we infer
  from them.
• (It also links our memories to the facts they are
  memories of.)
• So how do we come by our knowledge of cause and
  effect?
• Hume says we have no a priori grounds for this
  only experience can do the job.

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An argument

• No one can tell what the effects (or causes) of
  an entirely new and unfamiliar sort of thing will
  be.
• Adam could not have known, simply from looking at
  it or feeling it, that water would suffocate him
  or fire burn him.
• Familiar causes and effects may seem, to us, to
  be obvious but only experience makes them so
  (the billiard table).
• How could the mind supply us with such
  information on its own? There are no necessary
  relations between (separate) facts!

13
Trouble

• Now, how do we reason from experience to our
  conclusions about cause and effect?
• Is this reasoning any good?
• Hume is worried!
• He says, even after we have experience of the
  operation of cause and effect, our conclusions
  from that experience are not founded on reasoning
  or any process of the understanding. (225)

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Like causes, like effects?

• We always presume when we see like sensible
  qualities that they have like secret powers.
• Past experience applies only to those particular
  objects and situations.
• It just doesnt follow that similar objects and
  situations will produce similar results. No
  reasoning justifies this expectation.

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Experience and reason dont do it.

• If something about a pattern of events shows that
  the pattern was necessary, we should see it (and
  be able to reason it out) the first time we
  experience the pattern.
• Yet we dont reach the conclusion that the
  pattern must be followed in every instance when
  we first see it. We need repeated experience to
  reach this conclusion.

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What does needing repetition show?

• If some kind of argument links cause to effect,
  then we should be able, once weve clearly
  grasped the cause, to infer that the effect must
  follow.
• If the argument infers a necessary connection
  from the experience of a repeated pattern, Hume
  asks what this medium joining cause and effect
  is supposed to be, and how repetition leads us to
  detect it?

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Furthermore, it should be obvious

• Animals and babies clearly reach these kinds of
  conclusions too.
• So any reasoning (or experience) that tells us a
  pattern will continue should be obvious when we
  think about it.
• if I be wrong (i.e.there is an argument
  linking cause to effect)I cannot now discover an
  argument whichwas perfectly familiar to me
  before I was out of my cradle.

18
What could repetition add?

• Humes view is that the only thing repetition of
  the pattern could do for us is to build a pattern
  in us, a habit of regularly expecting the effect
  whenever we witness the cause.
• Hume concludes that the experience of persistent,
  regular patterns leads us to form this kind of
  habitual expectation.
• But theres no justification we can give for this
  expectation it really is just a habit.

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The regress.

• Hume asks what sort of justification we could
  give, of basing our expectations about the future
  on the experience of regular patterns in the
  past.
• The only justification available seems to be that
  weve been successful, in the past, when we do
  this, i.e. these expectations have proven right.
  
• But thats just another past pattern, and the
  question here is what reason we have to think
  that past regular patterns will continue into the
  future!

20
Skeptical Modesty

• Hume defends a skeptical response to this puzzle.
• Even though there is no reason to expect the
  future to resemble the past, nature leads us to
  this expectation.
• A calm, skeptical attitude fits perfectly here
  we accept that we have no good reason for this
  expectation, but we have the expectation anyway.