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Lecture

Week 10 notes


Department
Philosophy
Course Code
PHLA10H3
Professor
William Seager

Page:
of 3
Philosophy Week 10 Notes
Is PUN a priori?
-can we give a deductive proof of PUN?
-Is it possible that nature should not be uniform
-It seems possible, therefore, PUN sis not a priori
Therefore, PUN is a Posteriori
-so it must be proven either by observation or induction
-we cannot observe PUN because it is about the future
-so we must give an inductive argument for PUN
Therefore, the argument will contain an assumption
-the assumption – according to HUME – will be PUN
-although this is circular reasoning and cannot show PUN
Ex. Argument:
-in the past, PUN has always been true
-therefore, inductively, PUN is true
Hume notes that this argument depends on the assumption that nature will continue to obey PUN
The argument ought to be:
-in the past, PUN has always been true
-PUN
-Therefore, PUN is true
This argument fails because it blatantly assumes what it wants to prove
Hume’s attitude towards induction
-Hume thought we should reason inductively even though we have no rational reason to do so
-He thought we (and many other animals) are naturally structured to believe in and use induction
-Ex. Pavlov’s dogs
-Hume sometimes called this “habit
-He also noticed instincts – which arebuilt in” by nature and carry information about how organisms
“expect the world to work
-Hume wondered how instincts arose and came somewhat close to a concept of evolution
-But rationality cannot support the beliefs and expressed in instinct or by the habit of inductive inference
But is PUN needed for inductive arguments or the attack on induction?
What exactly is the content of PUN?
Is nature alwaysuniform”?
-do the seasons of the year show uniformity or diversity?
-Is the death of animals a feature of natural uniformity or a sudden dis-uniformity in an animals life
-It seems impossible to state PUN in any non-trivial way
-But PUN is not needed to create the problem of induction
Induction and reliability
-we want our inductive knowledge to be secure
-lets say that a Reliable method of inference is one that usually leads to the truth
o‘usually’ can be thought of as a scale, from the not very reliable to the highly reliable
o– ex. Prediction of solar eclipse – highly reliable
This scale can be expressed in terms of probability
-the probability of an eclipse given what we know about sun, earth and moon is virtually 1
-the probability of rain next week given our current knowledge is slightly more than 0.5
Sober’s version of the problem of induction
www.notesolution.com
-how do we know that induction in general is a reliable way to get knowledge?
Sobers new version of the problem of induction
-how do we know that induction in general is a reliable way to get knowledge?
-Now we replay Hume’s point
-Either we can deductively prove that induction is a reliable way to get knowledge or
-We have to inductively prove it is reliable
- There is no way to prove deductively that induction is reliable (because we can consistently imagine
induction failing)
-But to prove that induction is reliable inductively is to argue in a circle
-PUN plays no part in this argument
Sober’s version of the problem of induction
-think about what this means
-we have zero reason to think that induction is reliable
-this implies that we have no reason to believe what is inductively reasonable versus the opposite
-ex. We have zero reason to believe that the sun will rise tomorrow- it is exactly as reasonable to believe
it will not rise as that it will?
-How can that be right?
-Can we save induction
Strawson’s attempt to save induction
-maybe it is an analytic truth that induction is a rational way to amplify knowledge
-strawson seems to be claiming that the idea that induction is a good way to reason is part of the concept
of rationality
-suppose that is true
-would this prove that induction is reliable?
-It would seem not
Blacks attempt to save induction
-recall the argument in favour of induction:
oinduction has been successful in the past, so it will be successful in the future
Is the argument in favour of induction really circular?
-note that the difference between premise of an argument and a rule of inference
-black argues that an argument is circular just in case the conclusion appears (maybe only implicitly)
among the premises
-on that understanding, the inductive argument in favour or induction is not circular
-it just uses the inductive rule of inference
Is Black’s notion of circularity right?
-or is there something wrong with an argument that defends from of argument which you can accept only
if you already accept that from of argument?
We could also ask Black:
-even if we could give this inductive proof of induction would that show that induction is reliable?
-No, because counter-induction (CI) is equally supported by a counter-inductive argument
-CI = if X has happened in the past, except not-X
-Ex. Gamblers fallacy
The CI argument in favour of CI
-CI has failed in the past, so expect it to succeed in the future
-This is a good CI argument!
Sober’s trip beyond foundationalism
www.notesolution.com
-note how sober divides knowledge claims into 3 levels
-1. indubitable beliefs ( a priori/ introspectible )
-2. present and past observations
-3. predictions and generalizations
Descartes had problems getting from 1 to 2
Hume adds problems getting from 2 to 3
-sober thinks there is no way to
omove deductively from a level to a higher level
oeven use lower level stuff as evidence as higher level
that is IF one is restricted to the lower level
this is because something is evidence only relative to additional “background beliefs
-ex. Phantom limb pain
The Relativity of evidence
-suppose we have this evidence : we have examined 10,000 emeralds and they are all green
-is this evidence for: all emeralds are green
-not if we also believe X: there are many emeralds and they are 99% green OR all emeralds are green but
there are very few emeralds in the world
notice that X is not a level 2 statemetn
sober’s thesis: no strictly level n statement justify any level n+1 statements
-why? Because of the relativity of evidence
-what if we had no level n+1 beliefs?
-Then we could say nothing about level n+1 based only on level n evidence (except for trivial or a priori
truths)
-Is that true?
Anti-foundationalism about justification
-isrational justification” strictly about inter-level justification?
oIf so, Sober thinks its impossible to achieve
-or is there a sense of “rational justification” that takes into account our current epistemic position?
-That is, could we say something like
oGiven our current epistemic situation (what we believe now) evidence E would justify belief P
This assumes an idea of “shared epistemic situations
-amongst physicists, it is sharedknowledge that the external world is real
-example of ‘disputed fact in the legal world…
-so the induction has been justified ??
www.notesolution.com