epistemology Flashcards
three kinds of knowledge
Acquaintance - “I know Sally” - personally acquainted with someone, or a place, etc
Know how - I know how to ride a bike - I have a certain skill
Propositional knowledge - I know that 3+5=8, there are things that I stand in certain relation to
propositions
Propositions state a possible way for things to be - they can be true or false depending on how the world is
eg. The proposition that grass is green states that grass is green
abstract objects
propositions that are not spatiotemporal. In this respect, they are like numbers
Propositions should be distinguished from sentences
Two distinct sentences may express the same proposition
propositional attitudes
propositional knowledge is a relation that an agent stands in to propositions
eg. Belief: Yuko believes that Herman will arrive late
Fear: Xavier fears that Helen will arrive late
Wishes: Simone wishes that Samuel would arrive late
that-clauses
In general attitude verbs that take that-clauses express propositional attitudes
ambiguity in the types of knowledge
it can be unsure what knowledge is which - for example, proposition knowledge “I know Sally” - acquaintance knowledge, but also could be propositional knowledge that I know facts about Sally
Knowledge as Belief
To know P is just to believe P
knowledge entails belief
However, not every case of belief is knowledge, you are able to believe false things
Knowledge’ can’t just be belief, as knowledge seems to have a property that belief doesn’t
By Leibniz’s law, we can say that belief and knowledge are distinct
factive
Things that are known to be true
A factive attitude Q is one such that from A Qs that P, we can infer P
Knowledge as True Belief
To know P is to have a true belief that P
Believing truly is factive
However, not every case of believing truly is a case of knowledge
you can know true beliefs just from lucky guesses, but you can’t know something from just guessing
Knowledge as a Justified True Belief
Justification would seem to be a necessary condition for knowledge. But it is not a necessary condition for having a true belief
To know P is to have a justified
true belief that P
A knows that P just in case A has a justified true belief that P
We want to ask: Are there any possible cases in which (i) A has a justified true belief that P, but (ii) A
does not know P
Justification
justification is person relative
Suppose I see Hanna engaging in various suspicious activities, but you know Hanna as a
pillar of the community.
Then I may be justified in believing that Hanna is a spy, while you would not be justified in believing
that Hanna is a spy.
The reason that justification is person relative is that justification depends on your evidence
connection between justification and belief
justified beliefs should be more
likely to be true than non-justified beliefs
But it’s tricky to spell out in exactly what sense this is true
However we can have cases of knowledge that are not justified - eg. coin example of flipping a coin and it being right
you can also have justified beliefs that aren’t true
you can also have justified beliefs that aren’t true
incredibly reliable watch. It
has never let you down.
Unfortunately today, as a result of a very unlikely glitch, it has stopped working
Looking at your watch it says 11:30, and on this basis you come to believe it’s 11:30. It is, however, 10:30
In this case, it’s natural to say that you’re justified in your belief, despite the fact that it is false
The reason that you can have false justified beliefs is that sometimes very good evidence can be misleading
Justification is something that comes in degrees
Suppose that your evidence entails P
For example your evidence might be Q, R, and the proposition for which it is evidence might be (Q and R)
In this case you have maximal justification for believing the proposition
But sometimes even though your evidence doesn’t entail P, it still makes P very likely
Suppose your evidence is that a bag B contains 100, 000 marbles only one of which is red.
Then your evidence makes it very likely that if you draw a marble it will be non-red
Given that justification comes in degrees, a natural question for the proponent of the JTB account is
what level of justification is required for knowledge
answer to what level of justification is required for knowledge (1)
The simplest answer would be maximal justification
But this might seem too demanding
Suppose I parked my car outside my office just before coming to class
It seems plausible that I know that my car is parked outside my office
But although my evidence makes it very likely that my car is outside, it isn’t clear that it entails that my
car is outside, it could have been stolen
Still in this case the natural thing to say is I know that my car is parked outside
answer to what level of justification is required for knowledge (2)
So let’s take the JTB account to say, somewhat vaguely, that one requires some sufficiently high level of justification, where this may fall short of maximal justification
When we say that a body of evidence supports P, It’s important that what we mean here is that the total body of evidence that you have supports P
It can happen that some proposition E1 is part of your evidence and that E1 supports P, but your total body of evidence does not support P
An example: If you walk into a room and the wall looks red, then the wall’s looking red is part of your evidence.
This proposition supports believing that the wall is red
However, if you learn that there is trick lighting, then you shouldn’t believe that the wall is red
In this case, you have some evidence, namely, that the wall looks red, that supports a belief P, but your total body of evidence: that the wall looks red, and there is trick lighting, does not support that belief
Here we say that the proposition that there is trick lighting defeats the evidence that the wall looks
red
defeasability approach
D defeats E as evidence for P just in case E is evidence for P, but D and E is not evidence for P
Note that evidential defeat can itself be defeated
An example: You go to a party of 100 people and you learn that 98% of the people are accountants
This supports believing that Max, who is at the party, is an accountant
You then learn (i) there are four people wearing vests, (ii) the two non-accountants are wearing vests, and (iii) Max is wearing a vest
This defeats this first bit of evidence
Finally, you learn that only the accountants have gold pens, and Max has a gold pen
This defeats the previous evidence that undermined your initial reason to believe that Max is an accountant
You now again have good—indeed conclusive—reason to believe that Max is an accountant
Ok, so to be justified in believing P, then, is for one’s total evidence to support P to a sufficiently high degree
Problem with JTB
if this analysis is correct then, at a
minimum, the following conditional must hold: A knows P just in case A has a justified true belief
that P.
One direction is certainly fine.
The question we want to focus on is whether they are jointly sufficient for knowledge
The question we want to consider is whether there are possible cases in which one has a justified and true belief that P, but one does not know P
the answer to this is yes
Assume, as before, that your watch has stopped working and that it shows 11:30 as the time
But now imagine that instead of looking at your watch at 10:30, you look at it, by chance, at 11:30, and so come to judge that it is 11:30
In this case, by looking at your stopped watch you come to form the true belief that it is 11:30
Moreover, as in the previous watch case, it would seem that since your belief is based on a normally
highly reliable watch, you true belief is also justified
In this case, then, it looks like your belief that it is 11:30 is true and justified, however it is not knowledge, as looking at the stopwatch was no way of learning what the time was
we have a case where we have a justified true belief, but not knowledge
another problem with JTB
other cases in which it would seem that one can have a justified true belief without having knowledge
there are cases in which logically valid
inferences would seem to give rise to justified true beliefs that don’t amount to knowledge
Smith and Jones have applied for a job
Smith has strong evidence for:
(J) Jones will get the job and Jones has ten coins in her pocket
On the basis of this Smith deduces:
(J*) There is someone who will get the job and who has ten coins in their pocket
this is a logically valid inference - as if F, therefore something is F
Now let us suppose that, as a matter of fact, the evidence about the job is misleading. In fact, Smith will get the job
And, though Smith doesn’t know this, it turns out that Smith has ten coins in his pocket
J* is still true and justified - it’s justified because Smith has good evidence for it - and J entails J*
but it’s still not the case that Smith knows this
For the reason that (J*) is true is that Smith is the person who will get the job. But Smith doesn’t know that he’ll get the job. And Smith doesn’t know how many coins he has in his pocket
So it looks like if we make the plausible assumption that logically valid inferences preserve justification
then we can have justified true belief without knowledge
A key feature of the preceding is that our logically valid inference takes us from a false (but justified) belief to a true (and seemingly justified belief)
Note that this is possible since while logically valid inferences can’t take us from truths to falsehoods, they can take us from falsehoods to truths
another case problem with JTB
(F) Jones owns a Ford
From this Smith then forms the following belief (amongst other similar beliefs):
(F*) Either Jones owns a Ford, or Brown is from Barcelona
Now suppose that the evidence about Jones’ car is misleading
However, as a matter of fact Brown is from Barcelona
This, though, is not something that Smith has any evidence for at all!
F* is a justified true belief, but it is not a case of knowledge
For the reason that (F*) is true is that Brown is from Barcelona. But this is not something that Smith knows
these are called Gettier cases
What would seem to be going on in the problem cases is that the justification for the claim in
question and what makes the claim true aren’t properly connected
gettier cases
named after Edmund Gettier who noted these sorts of counterexamples to the JTB account
of knowledge
recipe:
(1) Start with a case in which someone has justified belief in some false proposition P1
(2) Find some logically weaker proposition P2 which is true
To say that P2 is logically weaker than P1 is to say that P2 is entailed by P1, but the reverse is not true
(3) Assume that the agent comes to believe P2 by deducing it from P1
Principle of Deductive Closure
f (i) S is justified in believing P, and (ii) P entails Q, and (iii) S comes to
believe Q as a result of inference from P, then S is justified in believing Q
Amendments of the JTB account
JTB+1: To know P just is to have a justified true belief that P and to be such that one’s grounds for
believing P don’t include falsehoods
counter argument:
(J1) Jones works in my office and has always driven a Ford in the past and just drove by in a Ford
From this you infer: (J2) There is someone who works in my office who
has always driven a Ford in the past and who just drove by in a Ford
(J3) Someone in my office owns a Ford
But, let us suppose, that Jones does not in fact own a Ford. But someone else at your work, who you do not know, does own a Ford
In this case you have a true belief, that’s justified and that isn’t based on false grounds
However, it’s natural to say in this sort of case that you do not know that someone at your work owns a
Ford
JTB+1 is also too demanding
It would seem that there may be cases in which you know and, amongst your grounds for believing
something, there is some false proposition
eg. you ask twenty witnesses whether
they saw a particular crime. 19 did and truly report this. The other did not but says they did
it would seem that you can know that
the crime took place. But one of propositions that this belief is based on is false
