Exam #1 Answers

A theory of knowledge is a statement of
the necessary and sufficient conditions for propositional knowledge. In
other words, a statement of this form:
For any person, S, and proposition, p,
S knows that p if and only if __________.
Such a theory provides an answer to the
question, "What is knowledge?"
(b) What is the JTB Theory of Knowledge?
Here is the official statement of the JTB
theory:
S knows that p if and only if
(i) S believes that p, and
(ii) p is true, and
(iii) S is justified in believing that p.
(c) Present one of the Gettier-style counterexamples to the
JTB theory of knowledge.
Suppose I see Caleb's driver's license and
it says he is from Oklahoma City. I come to believe that
(1) Caleb
is from Oklahoma City.
I am justified in believing that Caleb from
Oklahoma City, since seeing a driver's license from Oklahoma City
is pretty good evidence.
Suppose I infer from (1) that
(2) Someone
in my class is from Oklahoma City.
Certainly, if I am justified in believing
(1) and I deduce (2) from (1), then I am justified in believing
(2).
Now, suppose that Caleb's ID was a fake.
He's not really from Oklahoma City. Clearly, I don't know
(1), since it's not even true (though I was still justified in
believing it -- justification does not require truth). So
far so good for JTB, since JTB yields the correct result here
-- namely, that I don't know (1).
It also seems that I don't know (2), either,
since I inferred it from (1), something I didn't know.
But suppose finally that, unbeknownst to
me, someone else in the class is, just by luck, really from Oklahoma
City. That is, just by luck, (2) is true. Now, we agreed
that I don't in fact know (2). But the thing is, I have
a justified true belief that (2). So here is a case
in which I have justified true belief without knowledge. Since
JTB says that anytime someone has a justified true belief that
p, he thereby knows that p, JTB is proven to be false.
We could make Gettier's counterexample into
a little argument, as follows:
A Gettier-style Argument against JTB 1. If JTB is true, then I know that
someone in my class is from Oklahoma City.
2. I don't know that someone in my class is from Oklahoma City.
3. Therefore, JTB is not true.
2.(a) Who is David Hume? About when
and where did he live? Tell me some "fun facts" about
Hume.
David Hume was an 18th century British philosopher. He
is considered the greatest philosopher to write in the English
language. Immanuel Kant, perhaps the greatest German
philosopher in history, said that reading Hume "awoke me
from my dogmatic slumber."
(b) Explain the distinction between relations of ideas and
matters of fact. Give one example of each.
relations of ideas
- statements that are made true simply in virtue of the concepts
contained in the statement
For example, 'All triangles have three
sides'.
matters of fact
- statements that are not relations of ideas
For example, 'The earth revolves around
the sun'.
3. Here is Hume's Problem of Induction:
1. If there is any reason to believe
in PUN, then our justification for PUN is either a priori
or a posteriori.
2. Our justification for PUN is not a priori.
3. Our justification for PUN is not a posteriori.
4. Therefore, there is no reason to believe in PUN.
5. If there is no reason to believe in PUN, then there is no reason
to believe the conclusion of any inductive argument.
6. Therefore, there is no reason to believe the conclusion of
any inductive argument.
(a) For each premise of Hume's argument,
(i) explain the meaning of any technical
terms contained in it (e.g., 'a priori', 'a posteriori', 'PUN',
'inductive argument').
(ii) give its rationale (i.e., the
reason the line is (or seems to be) true).
1. If there is any reason to believe in
PUN, then our justification for PUN is either a priori or a posteriori.
Technical Terms
- PUN is the Principle of the Uniformity of Nature. It
claims that the future will resemble the past.
- a priori statements - statements one can know, or be
justified in believing, without needing to appeal to any particular
experience to serve as evidence for the statement.
- a posteriori statements - statements that can be known,
or justified, only by experiencing the world.
Rationale
Premise 1 is true because these two options -- a priori
and a posteriori -- are, by definition, exhaustive. For
any proposition, our justification for believing it must be either
a priori or a posteriori.
2. Our justification for PUN is not a
priori.
Rationale
Hume endorses the plausible thesis (which we called "A Humean
Thesis") that a statement is a priori only if it is
a relation of ideas. Given this thesis, if PUN were
a priori then, it would be a relation of ideas. But
PUN is not a relation of ideas -- we can coherently imagine PUN
being false. There is no contradiction is supposing that the future
is utterly unlike the past in the way nature operates. It
is at least coherent to suppose that, e.g., all of a sudden brake
pedals no longer stop cars or bread no longer nourishes.
3. Our justification for PUN is not a
posteriori.
Rationale An a posteriori justification
for PUN would have to come in the form of an argument with premises
about our experience and with a conclusion that is PUN itself.
Such an argument must be either a deductive or an inductive
argument. That is, our reasons for believing PUN would either
have to deductively entail that PUN is true, or would have to
inductively support PUN (i.e., make PUN more likely).
Deduction won't work. Because none of our experiences, which of
course are only of the past and the present, deductively imply
anything about the future.
Induction won't work. Of course, we usually use inductive arguments
to draw conclusions about the future based on our experience of
the past. And this is exactly what we're trying to do here
-- we're trying to infer PUN (a claim about the future) from our
experiences of the past. But we can't use an inductive argument
to establish PUN, because all inductive arguments for conclusions
about the future presuppose PUN. They need to use
PUN as a premise. So they certainly can't establish it as
a conclusion. That would make the argument circular.
4. Therefore, there is no reason to believe
in PUN.
[follows validly from (1), (2), and (3)]
5. If there is no reason to believe in PUN,
then there is no reason to believe the conclusion of any inductive
argument.
Technical terms: Inductive arguments are arguments in which the truth of
premises does not guarantee the truth of the conclusion, but in
which they do make the conclusion more likely. Here
is an example of an inductive argument:
Every time I have pressed the brake pedal
in my car, my car has stopped.
==================
The next time I press my brake pedal, my car will stop.
Rationale Premise 5 is true any inductive
argument implicitly uses PUN as a premise. If your
only argument for some conclusion has a premise that you have
no reason to believe, then you also have no reason to believe
the conclusion.
6. Therefore, there is no reason to believe
the conclusion of any inductive argument.
[follows validly from (4) and (5)]
(b) Make it clear how radical the
conclusion of Hume's argument is. (You might do this by giving
some examples of the sorts of things we have no reason to believe,
if the conclusion is true.)
Since we use induction all the time, this
conclusion (line 6) is extremely radical. If 6 is true,
then we have absolutely no reason at all to believe any matter
of fact about the future. For instance, we have no
reason at all to believe that the next time I press my brake pedal,
my car will stop, or that the next time I drink water, it will
quench my thirst instead of burning my throat like acid. Hume's
conclusion does not merely say that we cannot know these
things. It says that we have no justification whatsoever
for our belief in them.
(c) What do you think about Hume's
Problem of Induction? Does it really establish this radical conclusion?
Discuss your reaction to Hume's argument.
I have to say that I am pretty disturbed
by Hume's argument. I see no way out of it. Each
premise seems rock solid. Since it is valid, I guess
I have to accept the conclusion. And to think, all
this time, I thought I was such a rational guy.
There is a way to take some of the sting
out of Hume's Problem of Induction, however (as pointed out by
Sober). We can admit that we have no rational basis
for believing in PUN. But, about all the beliefs we
form on the basis of PUN, we can say that they are fairly rational
given PUN. So we have a sort of relative rationality. We
can say that, given PUN, it is more rational to press the brake
pedal of my car in order to stop it, instead of pressing the radio
dial to stop the car. True, on a absolute bases, both
of these practices are completely unjustified. But
relative to PUN, the former is more reasonable. Since
we can't have absolute rationality, I guess this relative rationality
is better than nothing.