BTK 05 - Goldman

8/3/2019 BTK 05 - Goldman

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BTK05: Goldman (1 of 3) Week 2

Goldman,Discrimination and perceptual knowledge

An alternative to Cartesianism

Goldman claims that the traditional Cartesian view is that an analysis ofknowledge requires a theory of justification:

S knows P only if S is justified in believing that P. S is justified in believing that P only if P is either self-justified or justified by

something which is self-justified.

The problem. If S knows P, then either P is self-justified or justified bysomething which is self-justified. So, ultimately, whatever S knows must

bottom out in self-justified believes.

Our perceptual knowledge does not seem to be self-justified, and so must bejustified by other self-justified beliefs.

Goldman doubts the prospects of showing that there are any. So, Cartesianism seems committed to skepticism. Goldman takes it for granted that skepticism is false, and so that the

Cartesian view which encourages it must be rejected.

Specifically, Goldman rejects any appeal to justification and, instead,endorses a kind ofreliabilism.

Reliabilism.According to reliabilism, whether we know something or notdepends not upon what justification we have for believing it, but whether ourbelief was produced by a reliable process.

A process is reliable if (i) it produces true beliefs in actual situations and (ii)would produce true beliefs (or at least inhibit false beliefs) in relevant

counterfactual situations.

In order to be reliable, a process must be able to discriminate betweenincompatible states of affairs.

Reliabilism is externalist in the sense that whether a given belief isproduced by a reliable process is not typically part of our available evidence.

Relevant alternatives

Goldman asks us to consider the following case: Fake barn example. Henry is excellent at identifying barns. So we think

that if he identifies something as a barn, he knows. But suppose we learn


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that hes driving through a strange county where there are many fake barns.

If Henry saw one of these, he would mistake it for a barn. Because of this,

even if Henry actually sees a barn, we would not say that he knows that what

he sees is a barn.

What explains the change in our view about whether Henry knows? Traditional Cartesianism cannot explain the change in our view, since in

both scenarios, Henry has the same justification for believing that he sees a

barn.

Goldman suggests an alternative explanation: to know that it is a barn wouldrequire ruling out any relevant alternative in which it isnt a barn.

Henry doesnt know because: There is a relevant alternative state of affairs in which what Henry

sees is a fake barn.

Henry is unable perceptually to discriminate seeing a barn fromseeing a fake barn.

But Henry would have known were he able to discriminate these relevantalternatives.

This suggests a new account ofknowledge. Knowledge. S knows that P iff the actual state of affairs in which P is true is

discriminable by S from a relevant possible state of affairs in which P is false.

One question (which Goldman sets aside) is whether our concept ofknowledgeitself determines, for any given situation, which alternatives

are relevant or whether that is a matter of various psychological orlinguistic regularities.

Perception as a reliable discriminating mechanism

One perceptuallyknows P ifthe beliefs thus produced fit what is perceived. As a guiding example, Goldman suggests that Sam knows its Judy, not Trudy, if

he can discriminate perceptually between them.

Sam can perceptually discriminate between Judy and Trudy only if it isfalsethat: were he looking at Trudy, then he would believe it was Judy.

Counterfactuals. These are claims of the form: were P true, Q would be true(where P is actually false).

Were Hilary to have won more states, she would be the nominee. Were I a bird, I would have wings.


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Perceptual knowledge. Sperceptually knows P iff (i) S perceptually believesP; (ii) P is true; and (iii) there is no relevant contrary Q of P such that, were Q

true, S would still believe P.

A perceiver will then (i) acquire perceptual experiences from their perceptualmechanism which (ii) accordingly produce beliefs.

Perceptual equivalence

Dachshund counterexample. If I am prone to mistake wolves for dogs, thatdoesnt seem to preclude my knowing that Dack the dachshund is a dog when I

see him from afar. But it does, since (iii) fails.

Wolf perceptions are produced in a very different way then dog perceptions:they areperceptually inequivalent.

We can avoid the counterexample by requiring excluding as irrelevantperceptually inequivalentalternatives.

To specify whether an alternative is perceptually equivalent, we must have somegeneral idea of how to compareperceptual states of affairs.

Roughly, a perceptual state of affairs is an object, its properties, and aperspective from which that object is perceived (DOE relation).

We may then compare two perceptual states of affairs and see whether thesame object, properties, or DOE relations are involved.

Perceptual equivalence doesnt require that these two perceptual states ofaffairs be identical.

Their close similarity is good enough, so long as they would produceperceptual experiences which do not differ in any causally relevant way to

ones beliefs in question.

If a difference in shape between Judys and Trudys eyebrows is notregistered by Sam, then it is not a perceptual difference which is

causally relevant to his beliefs in question.

So, his Judy and Trudy experiences are perceptual equivalents. We then can explain what happens in both the fake barn and dachshund

examples: We avoid the dachshund counterexample by claiming that a wolf experience

is not a relevant alternative because it is not perceptually equivalent to a

dachshund experience.

We explain why Henry didnt know by claiming that a fake barn experience isa relevant alternative because it is perceptually equivalent to a barn

experience.

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BTK 05 - Goldman