01/04/2005: Philosophical Ideas I: the Gettier problem
In addition to my Obscure Country of the Week series, I'll be doing a weekly series on philosophical ideas. There won't be much original philosophizing going on. I'm not doing much of that nowadays, and even if I was, I'm not sure it would blog well. The point of this series is to give you a taste of some of the problems and ideas that contemporary philosophers, at least in the English-speaking world, think and write about.
Most of these ideas will be in the fields of metaphysics and philosophy of language, which, along with history of early modern, were my areas of specialty. But the first idea in the series will come from the field of epistemology, the theory of knowledge: the Gettier problem.
Going all the way back to Plato, philosophers have tried to come up with definitions for concepts of philosophical interest. Probably the most famous historical example is the Republic, in which Plato tries to come up with a definition of justice. In the Theaetetus, Plato tries to come up with a definition of knowledge:
This attempt at definining knowledge is known as the Theaetetus thesis. In contemporary language, the Theaetetus thesis is that knowledge is justified true belief. (Plato, through his character Socrates, goes on to reject the Theaetetus thesis, for reasons unrelated to the Gettier problem.)
Socrates: But if true belief and knowledge were the same thing, the best of jurymen could never have a correct belief without knowledge. It now appears they are different things.
Theaetetus: Yes, Socrates, I have heard someone make the distinction. I had forgotten, but now it comes back to me. He said that true belief with the addition of an account (logos) was knowledge, while belief without an account was outside its range. (201d, trans. F. M. Cornford)
In a famous essay Is Justified True Belief Knowledge?" (Analysis 23, 1963), Edmund Gettier gives several counter-examples to the Theaetetus thesis: hypothetical examples of justified true belief that we would not classify as knowledge. Here's one:
(Paraphrase shamelessly stolen from Wikipedia.)
Smith has applied for a job, but has a justified belief that "Jones will get the job". He also has a justified belief that "Jones has 10 coins in his pocket". Smith therefore (justifiably) concludes (by the rule of the transitivity of identity) that "the man who will get the job has 10 coins in his pocket".
In fact, Jones does not get the job. Instead, Smith does. However, as it happens, Smith also has 10 coins in his pocket. So his belief that "the man who will get the job has 10 coins in his pocket" was justified and true. But it does not appear to be knowledge.
A lot of ink has been spilled on trying to come up with the elusive "Gettier clause" to complete a definition of knowledge. Suffice it to say, there's no general agreement among philosophers on a solution.
And although Gettier got his name attatched to the problem, Bertrand Russell came close to seeing it years earlier, in The Problems of Philosophy:
If a man believes that the late Prime Minister's last name began with a B, he believes what is true, since the late Prime Minister was Sir Henry Campbell Bannerman. But if he believes that Mr. Balfour was the late Prime Minister, he will still believe that the late Prime Minister's last name began with a B, yet this belief, though true, would not be thought to constitute knowledge. (second paragraph of chapter XIII)
Brock on 01.04.05 @ 09:57 PM CST