Lecture 2: The Gettier Problem

University of Wyoming, 1/26/04

 

Last time we saw that, while true belief may be a necessary condition for knowledge, it does not provide a sufficient condition for it. The problem, we said, is that a belief may be true by the sheerest coincidence; there is, to use a metaphor, no epistemic glue to hold the two conditions together. But that is precisely what we need in order to achieve knowledge.

 

This raises two questions. What is epistemic glue? And how strong does it have to be for knowledge (do we need superglue; or will Elmer’s suffice)?

 

For the moment, we will answer the first question simply by saying that epistemic glue is justification or the having of reasons/evidence that in some rational way support the belief.

 

But if justification provides the glue between our beliefs and their truth, how good does our justification need to be?  It is natural to break the answers to this question down into two classes: (i) The Superglue Class and (ii) The Elmer’s Glue Class.

 

According to philosophers of the first class, what is required for knowledge is certainty. Putting this in a slightly more revealing way, the Superglue crowd maintains that in order to have knowledge, our justifications must entail the truth of our beliefs. In shorthand:

 (justification ® truth)

Down this path lies the specter of skepticism[1] and, for that reason, we will hold off on it until next time.

 

According to philosophers of the second class, what is required for knowledge is mere justification (or a preponderance of the evidence, or good reasons). According to the Elmer’s glue crowd, it is enough that we have good reasons even if those reasons are consistent with the falsity of our belief. Thus, although the Elmer’s crowd believes that truth is necessary for knowledge, they reject the idea that our reasons for belief need to be so strong as to ensure that our belief is true―it is enough that they make the truth of our beliefs more likely (perhaps, much more likely).

 

As we are about to see, however, the Elmer’s approach has a problem of its own, namely, the Gettier Problem.

 

Here is a picture of the philosophical landscape:

 

Taken at face value, the Elmer’s glue approach is much more reasonable since it doesn’t set the standard for knowledge so high and appears to be far more consistent with our normal way of attributing knowledge.

 

The Gettier Problem

 

According to the present proposal, knowledge is justified true belief (where justification is not truth-entailing).

 

[G1]. Smith and Jones have applied for the same job and there is only one position to be filled. Smith has good reasons for believing the following propositions:

 

P1: Jones is the man who will get the job.

P2: Jones has 10 coins in his pocket.

 

Smith’s evidence for P1 is that the president of the company assured him that Jones would get the job. Smith’s evidence for P2 is that he counted the coins in Jones’ pocket 30 seconds ago.

 

But the following proposition, P3, follows simply by logic from P1 and P2:

 

P3: The man who will get the job has 10 coins in his pocket.

 

Suppose that Smith sees this entailment and, as a result, comes to believe P3. Now, since Smith is justified in believing P1 and P2 and since he sees that these claims entail P3, he is surely justified in believing P3.

 

But suppose further that Smith, not Jones is the man who will get the job (the president was lying to him, perhaps as a test); and suppose that, by chance, Smith also has 10 coins in his pocket (though he doesn’t know it). Under these conditions, P3 will be true.

 

Thus, Smith has a justified true belief that the man who will get the job has 10 coins in his pocket. But clearly he doesn’t know this!

 

[G2]. Suppose that Smith has strong evidence for the following claim.

 

P4: Jones owns a Ford.

 

Smith’s evidence for P4 is that Jones has always owned Fords in the past and Smith has seen him driving a Ford, etc.

 

Suppose Smith realizes that P4 implies the following claims:[2]

 

P5: Either Jones owns a Ford or Brown is in Barcelona.

P6: Either Jones owns a Ford or Brown is in Laramie.

P7: Either Jones owns a Ford or Brown is in Istanbul.

 

Suppose that Smith has no idea where Brown is. Clearly, Smith is justified in believing P5-P7 in virtue of the fact that he is justified in believing the first disjunct of each (i.e., P4).

 

Suppose, finally, that although Jones doesn’t own a Ford, Brown turns out to be in Barcelona. Thus, Smith has a justified true belief that either Jones owns a Ford or Brown is in Barcelona. (Note: he also has justified, but false beliefs that Either Jones owns a Ford or Brown is in Laramie and Either Jones owns a Ford or Brown is in Istanbul.) But he clearly doesn’t know that Either Jones owns a Ford or Brown is in Barcelona!

 

What’s gone wrong?

 

 

 

 

 

 

 

 


[1] Global skepticism is the thesis that we don’t know anything. Global skepticism has not been widely accepted and many philosophers think it is self-defeating. Consequently, philosophers have typically been skeptics about specific domains of knowledge; they believe that we can’t know anything about a certain domain. For example, some philosophers are skeptics about the external world (meaning that they believe that we can’t know anything about the external world, even that there is one). Although even these more careful formulations of skepticism are quite radical, we will see later that they are not particularly easy to dismiss.

[2] This holds because an ‘or’ statement is true if either conjunct is true.