Introduction:

In a paper that I was able to read in the time it takes me to microwave a bowl of popcorn, Edmund Gettier challenges the idea that knowledge is justified, true belief by providing two counter-examples in which the an agent has a justified, true belief and, yet, we don’t want to say that they have knowledge.

Case #451: Christmas Lights

Suppose that a certain graduate student, let’s call him ‘Nathan’, knows one of his fellow graduate students, let’s call him ‘Daniel’. Nathan has strong evidence for the following proposition:

1. After dusk, if the light is turned on at Daniel’s apartment, Daniel is inside.

Nathan’s evidence could be a number of things: whenever Nathan has dropped by in the past, and the light has been on, Daniel has always been at home. Conversely, whenever the light has been switched out, it has been the case that Daniel was out and about. Moreover, Daniel has testified to Nathan that it is easy to tell if he is at home: just look for the light.

Now winter break rolls around and, unbeknownst to Nathan, Daniel has traveled back home to see his family for the first week of break. Not wanting to attract burglars, Daniel has purchased a timer for his lights to give the “illusion” that he is at home. Nathan knows none of this. Each day of that week, as Nathan goes for his evening stroll, he passes by Daniel’s apartment, notices the light turned on, and formulates the belief that Daniel is inside. Finally, Daniel arrives back in Tucson, exhausted, and forgets to turn off his timer. As Nathan passes by on this evening, he once again formulates the belief that, because the light is turned on, Daniel is inside. Nathan has a true belief and it is justified by Daniel’s testimony and his past experience. Yet, he fails to have knowledge.

JTB: Necessary or Sufficient?

If we understand “justification” the way Gettier characterizes it, Gettier’s article makes a convincing case (for my money) that “justified, true belief” is not a sufficient condition for knowledge. We can craft a whole mess of cases in which a person has a “justified, true belief,” yet fails to have knowledge (generally because of the manner in which their “justified true belief” was formulated).

Regarding the question of whether it is a merely a necessary condition for knowledge, I am torn. It seems like there are naturally two paths one can travel down. On the one hand, we can travel the externalist route and say that the whole notion of “justification,” when conceived in the “internal” way that Gettier’s examples attack, is just confused and not necessary for knowledge at all. What matters is some external connection (causation) between a person’s knowledge and the truth/world. On the other hand, we can say that we need to hold onto an internalist sense of justification (making JTB a necessary condition) and simply add on further conditions to account for Gettier counter-examples. Regarding my own position, I am unsure. I think that externalism has a powerful response to Gettier examples, but I also believe in an internalist notion of justification and am not sure if I’m ready to give it up as a necessary condition for knowledge. So, I guess I would say that I am “leaning” towards viewing JTB as a necessary, but not a sufficient, condition for knowledge.

The Proper Subject of Epistemology

It seems that many philosophers before Gettier’s article were chasing down theories that held justified, true belief as the subject of epistemology. Gettier’s article takes a huge whack at such theories, suggesting that knowledge is the proper subject of epistemology and knowledge is not justified, true belief. While I agree with those philosophers who take “knowledge” to be the subject of epistemology, I’m not sure why we necessarily have to get rid of “justified” true belief. It seems to me that we can construe “justified” in ways that will match both internalist and externalist theories of knowledge. Thus, however the debate turns our, we could still take knowledge to be justified, true belief—we would merely differ on what counts as “justification.” For example, we could understand “justified” in the externalist sense (say, “reliably caused” and so forth) and we could also understand it in the way Gettier does. Perhaps the better word for it would be “warrant,” but I’m not sure the terminology really matters here.

Deduction

Consider the following principle:

1. “For any proposition P, if S is justified in believing P, and P entails Q, and S deduces Q from P and accepts Q as a result of this deduction, then S is justified in believing Q."

This principle is one that outlines the process of deduction: if I am justified in believing P, and I can deduce Q from P, then I am also justified in believing Q. Gettier lists this as one of his initial points and uses it to set up his counter-examples. I believe that Gettier believes that this principle is correct because he uses it to motivate his case against justified, true belief. However, it could be the case that Gettier is casting doubt on the process of deduction itself. In many Gettier examples, it is often the deduced proposition (Q) that lands the agent into trouble, suggesting that there might be a problem with forming certain kinds of inferences.

But, in my own opinion, the principle is mostly correct because it stays out of the “knowledge” arena by not taking account of the truth of P. All that the principle states is that S is justified in believing a deduced proposition, not that she knows the proposition. Now, I say mostly true because I am fairly convinced—both by Gettier cases and my own life—that it is not the case that we are always justified in believing deductions, precisely because we cannot guarantee the truth of the initial proposition. Hence, in the words of UNDER SEIGE II: DARK TERRITORY, “assumption] is the mother of all f#%$-ups.”

Consider a second principle:

1. For any proposition P, if S knows P, and P entails Q, and S deduces Q from P and accepts Q as a result of this deduction, then S knows Q.

-- DanielS - 07 Nov 2005