Gettier Is Justified True Belief Knowledge?
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ShaughanLavine - 30 Oct 2005
Gettier claims to prove, by means of counterexample, that knowledge is not just justified true belief. That is, he gives examples that he, and everyone else, take to be cases of justified true belief that are not knowledge. Since epistemology between Descartes (he suggests maybe even Plato) and Gettier has identified knowledge with justified true belief, that is taken to be an important result: epistemology has, as a result of Gettier's work, doubled its subject matter.
I'm a bit mystified by the universal acceptance. Why not take the examples to show something about justification, instead of knowledge? After all, "to know" is a good Anglo-Saxon verb, but "to be justified" is a philosopher's invention.
The principle that makes the argument work is:
If S is simultaneously justified in believing that P and that P entails Q, and S concludes Q from those beliefs, then S is justified in believing Q.
That is not what Gettier actually says: he omits the necessary condition that S is justified in believing that P entails Q.
That is not an uncontroversial solution, since it is not clear that 'P entails Q' is the sort of thing one can believe. That, I believe is why Gettier says what he does, instead, and it almost suggests reliablism by itself: what needs to be true about 'P entails Q,' well it isn't something that can be directly expressed as a state of S, and so one needs an external version, namely that the inference from P to Q is reliable.
Gettier gets it wrong in that he requires that P in fact entail Q, and that is irrelevant. What
is required is that S is justified in believing Q on the basis of P.
None of this requires S to know anything about it, it would seem. That is, Gettier says S is justified in believing P. Does that require that S know that S is justified? Surely not. Does it require that S be justified in taking Ss belief that P to justified? Probably not. Does the coherence of the picture require that S be able to distinguish justified from unjustified beliefs? I would suggest that it does. For one thing, otherwise S would never be in a position to make knowledge claims, which is not impossible, but at least one traditional part of epistemology has to do with figuring out what you are entitled to claim that
you know.
So it isn't quite clear what the game is. Gettier seems to take justification to be external. That is, S can be justified in believing that P whether or not S knows or is justified believing that S is justified in believing P. Gettier also seems to think that S is justified in concluding that Q from P so long as P, in fact, entails Q, whether or not S has any reason or justification for concluding Q from P. I'm taking that to just be a slip.
Suppose that S in fact is disposed to conclude Q from P whenever S believes 'P entails Q.' Then we can say that S is justified in believing Q if S is justified in believing P and justified in believing 'P entails Q,' if S has come to believe Q on the basis of those two beliefs via the disposition described.
All of this is to suggest that the notion of justification is itself subtle and the result of a philosophical theory. But then, why shouldn't we take the counterexamples to be counterexamples to the principle of justification instead of counterexamples to the claim that knowledge is justified true belief?
My answer to my own question, which is more a conjecture than answer I believe, is that "the tradition" always takes rational belief and rational knowledge (and rational justification?) to be deductively closed. For many purposes, that's a reasonable simplifying assumption, but, for many purposes, it isn't.
Now, let's look at the counterexamples. They take the form S is justified in believing P and P obviously entails Q. The conclusion is that S is justified in believing Q, but, as it happens, P is false, though Q is true, and so S does not know Q. The force of "obviously" is that the examples aren't strongly dependent on the details of the principle I criticized above.
Notice that the following principle is just fine:
If S knows that P and knows that 'P entails Q' (and has the right dispositions), and S concludes Q via the disposition as a result of the knowledge, then S knows that Q.
The same principle is also true if "knowledge" is replaced by "justified true belief."
What do I mean by "just fine"? Gettier's counterexamples don't touch that principle. They work only by have a false but justified belief as a premise.
One way of patching this up is to keep track of justifications. That suggests a theory of "defeaters." That suggests moving from traditional epistemology to a theory of "belief revision," which need not involve defeaters.
Of course, there are more traditional reactions: reliablism, coherentism (Lehrer if S knows Q, then Ss belief that Q doesn't depend on any false beliefs), foundationalism of defeasible knowledge ... .