[4.3.] Gettier and the Definition of Knowledge.

 

Edmund Gettier

·         born 1927, Baltimore, Maryland

·         Ph.D. from Cornell University, where his professors included Max Black and Norman Malcolm, who had been students of Wittgenstein

·         His first teaching job was at Wayne State University, and it was while he was there that he published “Is Justified True Belief Knowledge?” (1963), the paper that made him famous

·         today he is professor emeritus at the University of Massachusetts at Amherst

 

 

[4.3.1.] JTB Theory. 

 

How should (propositional) knowledge be defined? In other words, what are the conditions in which it is true to say that somebody has (propositional) knowledge?[1]

 

In the 1930s-50s, a consensus was more or less reached on an answer to this question. Most epistemologists agreed on the following:

 

Justified True Belief (JTB) Theory, a.k.a. the standard definition of knowledge:

S knows that P if and only if all three of the following conditions are met:

(1) it is true that P;

(2) S believes that P; and

(3) S is justified in believing that P.

 

JTB Theory states three conditions, each of which is individually necessary, and all of which are jointly sufficient, for knowledge.

 

This view (or something very close to it) was suggested by Plato and Kant. More recently, it was held both by (among others) the logical positivist A.J. Ayer (1910-1989) and by Roderick Chisholm (1916-1999), both members of the Tradition of Analytic Philosophy.[2]

 

 

[4.3.2.] Gettier Counterexamples. 

 

This consensus held until 1963, when Gettier’s “Is Knowledge Justified True Belief?” appeared in the journal Analysis.

 

Gettier argued that the JTB account is too broad, i.e., it counts as knowledge cases of belief which in fact are not knowledge (so it is too broad, in the sense of allowing as knowledge cases of belief that really aren’t knowledge—it lets in too much).

 

His argument consisted of two counter-examples, instances of JTB which he claimed were not instances of knowledge.[3]

 

 

[4.3.2.1.] A Crucial Assumption.

 

Before we look at those counter-examples, we need to notice that Gettier makes an important assumption:

 

“...for any proposition P, if S is justified in believing P, and P entails Q, and S deduces Q from P and accepts [believes] Q as a result of this deduction, then S is justified in believing Q.” (219)

 

E.g., suppose that I am justified in believing

 

P: The Atlanta Braves are playing in Atlanta tonight.

 

My justification is that I read it on the Braves’ web site, heard it announced on the radio, and saw an ad for Braves baseball on TV that specifically mentioned this game.

 

Here, P entails

 

Q: The Atlanta Braves are playing tonight.

 

Suppose that I deduce Q from P, i.e., on the basis of my belief that the Braves are playing in Atlanta tonight, I deduce that, simply, the Braves are playing tonight. Gettier’s point is that I am justified in believing Q, since I am justified in believing P and I deduced Q from P.

 

 

[4.3.2.2.] Counter-Example #1: The Man with Ten Coins.

 

Going for a job interview, Smith is informed by the boss that Jones is a shoe-in for the job and that there is no way that he (Smith) will get it.

 

While in the office, Smith spies Jones’s jacket draped over a chair and notices that there are ten coins in the pocket.

 

Now, bosses are reliable sources of information about who will and won’t get jobs; and one’s eyes are reliable sources of information about how many coins are in a given pocket.

 

So Smith’s belief that

 

(d) Jones is the man who will get the job, and Jones has ten coins in his pocket.

 

is justified. He then arrives at the justified belief that

 

(e) The man who will get the job has ten coins in his pocket.

 

What he doesn’t know is that (1) the boss was mistaken and that he himself will get the job and (2) he himself has ten coins in his pocket.

 

So Smith’s belief (e), that the man who will get the job has ten coins in his pocket, is true.

 

And it is also justified, given Gettier’s crucial assumption about justification.

 

So it meets the criteria set forth by JTB theory: if JTB theory is true, then Smith knows that the man who will get the job has ten coins in his pocket.

 

But, says Gettier, this is not a case of knowledge: Smith does not know that the man who will get the job has ten coins in his pocket.

 

 

[4.3.2.3.] Jones Owns a Ford.

 

Smith comes to believe that his coworker Jones owns a Ford; i.e., he believes that

 

(f) Jones owns a Ford.

 

Smith comes to believe this because he sees Jones driving a Ford, hears Jones singing the praises of Fords at the water-cooler, Jones offers him a ride while he (Jones) is sitting in a Ford, etc. His belief that Jones owns a Ford is justified, but, as it happens, false. Jones just borrowed the Ford he’s been driving.

 

Another coworker, Brown, has gone on holiday without telling anyone where he has gone. Smith has no reason at all to think that Brown is in any particular city, but yet comes to believe all of the following:

 

(g) Either Jones owns a Ford or Brown is in Boston;

(h) Either Jones owns a Ford or Brown is in Barcelona.

(i) Either Jones owns a Ford or Brown is in Brest, Belarus.

 

Smith comes to believe all of these because he knows enough logic to know that any disjunction [a disjunction is a statement of the form “p or q”] of which “Jones owns a Ford” is a part is true if “Jones owns a Ford” is true.

 

(We can suppose that Smith also comes to believe:

 

Either Jones owns a Ford or Brown is on Mars;

Either Jones owns a Ford or the moon is made of cheese;

 

and lots of other even sillier disjunctions. If in fact Jones owns a Ford, then any statement of the form “Either Jones owns a Ford or P” is true, no matter what proposition “P” stands for.)

 

Unbeknownst to Smith, Brown really is in Barcelona. So even though Jones really does not own a Ford, Smith’s belief (h) is true.

 

What’s more, it is justified, given Gettier’s crucial assumption about justification.

 

Thus, Jones’ belief that (h) is both true and justified. But, says Gettier it is not an instance of knowledge.

 

 

 

[4.3.2.4.] Summing Up Gettier’s View.

 

Gettier thinks that he had shown that the correct definition of “knowledge,” whatever it is, must be narrower than JTB theory, because JTB lets in instances of non-knowledge.

 

If he is right, then we have to either

 

(i)                 add a fourth condition to the standard definition, or

(ii)               abandon that definition altogether in favor of something stronger.

 

A big chunk of the history of epistemology over the last four decades has been devoted to revising JTB to save it from Gettier, or to replacing JTB altogether because of the sort of problem Gettier thinks he’s found.

 

 

[4.3.3.] Open Texture. 

 

But perhaps Gettier was wrong. Many philosophers have risen to the challenge of his counter-examples, arguing against Gettier in defense of JTB theory.

 

One promising response to Gettier is to say the following:

 

It is possible that the concept knowledge suffers from what Friedrich Waismann (1896-1959, a member of the Vienna Circle), called open texture.

 

open texture (df.): a concept has open texture if and only if it allows for the possibility that there are cases in which it neither definitely applies nor definitely fails to apply.

 

One of Waismann’s examples was the concept cat. Suppose that you see what appears to be a cat walking towards you. Suddenly, the creature grows in size until it is 20 stories tall—then just as suddenly, it shrinks back down to normal size.

 

According to Waismann, we would not know whether to say the creature is a cat. Our present concept cat just is not detailed enough, not determinate enough, to yield a definite answer to the question, “Is that thing a cat?”

 

This suggests a response to Gettier: our concept of propositional knowledge has open texture, too. Our experience can take unexpected turns not provided for in the meaning of the statement “S knows that P.”

 

Waismann’s notion of open texture is not the same as that of vagueness...

 

vagueness (df.): a concept is vague if and only if there are actual cases to which the concept neither definitely applies nor definitely fails to apply. E.g., bald: there are people who are definitely bald, and people who are definitely non-bald, and people who are neither definitely bald nor definitely non-bald. [We first encountered vague predicates in our discussion of Realism; see notes 3.7.3.]

 

On Waisman’s view, a concept is vague if there are actual cases for which it does not provide, while it has open texture if there are possible cases for which it does not provide; open texture is the possibility of vagueness.

 

 

The concept cat simply does not provide for all possible cases, and it is possible that the concept  knowledge is similarly deficient.

 

The language in which the word “knows” evolved is not designed to handle the very weird, highly uncommon circumstances that Gettier describes. It is only fixed enough to accommodate those situations which we typically encounter.

 

Perhaps if there were many actual cases of the sort that Gettier describes, we would know what to say about Gettier’s own cases, and our concept of propositional knowledge would be more detailed and determinate, such that we would know what to say about those cases.

 

 

Stopping point for Friday April 17. For next time, begin reading Moore’s “On Defining Good” (pp.314-319, to the end of section 11)