PHLA Knowledge and Reliability

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2 Internal Certifiability Knowledge is internally certifiable iff (1) there is an argument which shows that p must be true and (2) the premises of that argument are knowable a priori or by direct introspection Descartes s demanded that all knowledge be internally certifiable (small problem with basic knowledge what is the argument for the knowledge: I am conscious Let it be this: I am conscious; therefore, I am conscious) In most cases of knowledge there is an argument with (1) a subjective premise, (2) an objective conclusion and (3) a linking premise

3 Internal Certifiability Example: I know that grass is green Why: because grass looks green (subjective premise) and if grass looks green it is green (linking premise) Problem: I have to know the linking premise How can I know this? Danger of a regress (I know the linking premise only because I know something else...) Maybe I don t need to know the linking premise Maybe the linking premise merely needs to be true This is the idea behind the reliability theory of knowledge

4 What is epistemic reliability? Analogy: a reliable thermometer thermometers produce representations (or read outs ) of the local temperature the representation might be accurate or inaccurate depending on many factors a reliable thermometer is one which produces accurate representations in the conditions for which it was designed to operate consider the difference in reliability in an oven thermometer when used in an oven and if used to take a person s temperature (we might also consider the design error of a thermometer how close it gets and is designed to get to the real temperature in good conditions)

5 Is there a skeptical style argument against reliability? Is a thermometer unreliable because there are situations in which it does not work properly? all instruments are unreliable in some situations So if the fact that there was a situation in which an instrument was unreliable made the instrument unreliable in general then no instrument would ever be reliable That does not seem right Is a thermometer unreliable if we don t know whether it is in a situation in which it is reliable? Say we don t know if thermometer X is broken or not Does our lack of knowledge make X unreliable? It seems not whether X is reliable or not depends just on X and its situation; it does not depend on us

6 The analogy between reliability and knowledge A person is like a thermometer, except where the thermometer measures temperature, the person measures truth The RTK (reliability theory of knowledge) S knows P iff (1) S believes P (2) P is true (3) S is reliable about P (i.e. under the circumstances, if S believes P then P must be true) Note the must in clause (3) this is the concept of necessity Why is it needed here? Without it, S could fulfill (3) by accident

7 Logical Impossibility Impossibility based on definitions and logic example: it is impossible for a prime number greater than 2 to be an even number Nomological Impossibility Impossibility based on the laws of nature example: it is impossible for humans to fly merely by flapping their arms Circumstantial Impossibility Impossibility based on the particular situation example: My car can t go 60kmh now (because of traffic)

8 Is circumstantial impossibility/necessity real? Call the circumstances C. My car can t go more than 60kmh in C. This might mean that, given C, it would be nomologically impossible for my car to exceed 60kmh Perhaps we can define circumstantial necessity like this: NEC(C X) This way we don t need to add a new concept of necessity/possibility We still get what we want so long as C itself is not necessary General point about economy of thought We want to have the smallest number of basic concepts Nomological necessity can also be reduced NEC(L X), where L = laws of nature

9 RTK says that we know when it is circumstantially impossible for us to be wrong about our belief That is, S knows that P if it is circumstantially impossible for P to be false if S believes it This is like the reliable thermometer: it is reliable in circumstances where it cannot be wrong If it is the case that right now, in these circumstances, I can t be wrong that, say, I am in a lecture hall, then I know that I am in a lecture hall just in case I believe it Fred Dretske

10 This should mean that the skeptic cannot attack knowledge in the usual way. It does not matter that there is some other circumstance in which S could be wrong That fact (true though it is) does not make S unreliable The fact that there are some circumstances in which a thermometer is unreliable does not mean that the thermometer is unreliable, still less that it is unreliable in the present circumstances Even if S thinks she does not know, she will nonetheless have knowledge if she meets the conditions of the RTK This is completely different than Descartes s vision of internally certifiable knowledge

11 The KK principle If S knows P then S knows that S knows P Descartes s foundationalist theory of knowledge accepts the KK principle Why? If you know then you have grounds for your knowledge and you must be able to appreciate and in fact know these ground (otherwise you could doubt) If you know the grounds of your knowledge then you will know that you know (and you will know when you do not know) The RTK denies the KK principle Someone can have knowledge even when they have no idea whether or not they really know The thermometer analogy: the thermometer certainly does not (can not) know that it is reliable, but it might nonetheless be reliable.

12 The KK principle Example The unconfident examinee (from Colin Radford): Kate is asked on an exam to enter the date of Queen Elizabeth s death. She has studied well and would have had no trouble with this question except for exam time pressure panic. Under this pressure, she feels like she is guessing, but enters the date correctly. (1) Does Kate know that Elizabeth died in 1603? (2) Does Kate know that she knows?

13 The Power of Circumstances According to the RTK, whether S knows depends on the circumstances, C This makes knowledge relative; relative to C Consider the fools-barn example Suppose there s a place where most of the barns are mere facades If you drive into this part of the country, you suddenly don t know that there s a barn in a field (even if it s true) Why? Because in this place you are not a reliable barn spotter Even though you are reliable back home PHLA10 11

14 The Power of Circumstances The Zebra Problem Suppose you re at the zoo, looking at the zebras. Do you know they are zebras? You are reliable if, in the circumstances, if there was not a zebra in front of you, you would not believe you were looking at a zebra But what if the zoo sometimes paints horses to look like zebras (so that you could not tell the difference) In that circumstance you don t know So, do you know that these zebras are not painted horses? Are you a reliable zebra vs. painted horse spotter? NO! But if you know X is a zebra, and being a zebra logically implies NOT being a painted horse, don t you know that X is not a painted horse?

15 Israel restricts the importing of animals into Gaza, so the Marah Land Zoo's keepers covered the pair of donkeys in black and white stripes instead. Mohammed Bargouthi, the owner of the zoo, said it would have cost $40,000 to smuggle in a real zebra into Gaza. So, instead, he used French-manufactured hair dye. "The first time we used paint but it didn't look good," he said. "The children don't know so they call them zebras and they are happy to see something new." (08 Oct 2009, Telegraph)

16 Does knowledge grow by logic? It would have seemed that if (1) S knows that P and (2) S knows that P logically implies Q then (3) S knows Q The zebra (and barn) example seems to undercut this. Can that be right? This can be applied to the brain-in-vat problem too

17 Relativity of Knowledge What does it mean to say that some fact is relative It means that the truth depends on some context Example: Gertrude is very tall; she is 3 inches tall and she is a mouse / Fred is quite short; he is 5 10 but wants to join the NBA Einstein is famous for the theory of relativity What is relative? Time, mass, length example: twin paradox

18 Relativity of Knowledge If knowledge is relative, what about skepticism? The skeptic can say that no matter what we may think we know there is a circumstance in which do not know that thing The anti-skeptic can say: but in our present circumstances we do know things (and that s what matters) What about this question: Do you know you are not a brain-in-a-vat? Are you a reliable brain-in-vat non-brain-in-vat detector? Apparently not. But if you don t know this, has the skeptic won?