Knowledge as Justified True Belief

Knowledge as Justified True Belief

According to the following analysis, which is usually referred to as the "JTB" account, knowledge is justified true belief.

The JTB Analysis of Knowledge:
S knows that p iff

1. p is true;
2. S believes that p;
3. S is justified in believing that p.

Condition (i), the truth condition, has not generated any significant degree of discussion. It is overwhelmingly clear that what is false cannot be known. For example, it is false that G. E. Moore is the author of Sense and Sensibilia. Since it is false, it is not the sort of thing anybody can know.

Although the truth-condition enjoys nearly universal consent, let us nevertheless consider at least one objection to it. According to this objection, Newtonian Physics is part of our overall scientific knowledge. But Newtonian Physics is false. So it's possible to know something false after all.^[1]

In response, let us say that Newtonian physics involves a set of laws of nature {L₁, L₂,…, L_n}. When we say we know Newtonian physics, this could be interpreted as saying we know that, according to Newtonian physics, L₁, L₂,…, L_n are all true. And that claim is of course true.

Additionally, we can distinguish between two theories, T and T*, where T is Newtonian physics and T* updated theoretical physics at the cutting edge. T* does not literally include T as a part, but absorbs T by virtue of explaining in which way T is useful for understanding the world, what assumptions T is based on, where T fails, and how T must be corrected to describe the world accurately. So we could say that, since we know T*, we know Newtonian physics in the sense that we know how Newtonian physics helps us understand the world and where and how Newtonian physics fails.

1.1 The Belief Condition

Unlike the truth condition, condition (ii), the belief condition, has generated at least some discussion. Although initially it might seems obvious that knowing that p requires believing that p, some philosophers have argued that knowledge without belief is indeed possible. Suppose Walter comes home after work to find out that his house has burned down. He utters the words "I don't believe it." Critics of the belief condition might argue that Walter knows that his house has burned down (he sees that it has), but, as his words indicate, he does not believe it. Therefore, there is knowledge without belief. To this objection, there is an effective reply. What Walter wishes to convey by saying "I don't believe it" is not that he really does not believe what he sees with his own eyes, but rather that he finds it hard to come to terms with what he sees.

A more serious counterexample has been suggested by Colin Radford (1966). Suppose Albert is quizzed on English history. One of the questions is: "When did Queen Elizabeth die?" Albert doesn't think he knows, but answers the question correctly. Moreover, he gives correct answers to many other questions to which he didn't think he knew the answer. Let us focus on Albert's answer to the question about Elizabeth:

(E) Elizabeth died in 1603.

Radford makes the following two claims about this example:

1. Albert does not believe (E). Reason: He thinks he doesn't know the answer to the question. He doesn't trust his answer because he takes it to be a mere guess.
2. Albert knows (E). Reason: His answer is not at all just a lucky guess. The fact that he answers most of the questions correctly indicates that he has actually learned, and never forgotten, the basic facts of English history.

Since he takes (a) and (b) to be true, Radford would argue that knowledge without belief is indeed possible. But Radford's example is not compelling. Those who think that belief is necessary for knowledge could reply that the example does not qualify as a case of knowledge without belief because it isn't a case of knowledge to begin with. Albert doesn't know (E) because he has no justification for believing (E). If he were to believe (E), his belief would be unjustified. This reply anticipates what we have not yet discussed: the necessity of the justification condition. Let us first discuss why friends of JTB hold that knowledge requires justification, and then discuss in greater detail why they would not accept Radford's alleged counterexample.

1.2 The Justification Condition

Why is condition (iii) necessary? Why not say that knowledge is true belief? The standard answer is that to identify knowledge with true belief would be implausible because a belief that is true just because of luck does not qualify as knowledge. Beliefs that are lacking justification are false more often than not. However, on occasion, such beliefs happen to be true. Suppose William takes a medication that has the following side effect: it causes him to be overcome with irrational fears. One of his fears is that he has cancer. This fear is so powerful that he starts believing it. Suppose further that, by sheer coincidence, he does have cancer. So his belief is true. Clearly, though, his belief does not amount to knowledge. But why not? Most epistemologists would agree that William does not know because his belief's truth is due to luck (bad luck, in this case). Let us refer to a belief's turning out to be true because of mere luck as epistemic luck. It is uncontroversial that knowledge is incompatible with epistemic luck. What, though, is needed to rule out epistemic luck? Advocates of the JTB account would say that what is needed is justification. A true belief, if an instance of knowledge and thus not true because of epistemic luck, must be justified. But what is it for a belief to be justified?^[2]

Among the philosophers who favor the JTB approach, we find bewildering disagreement on how this question is to be answered. According to one prominent view, typically referred to as "evidentialism", a belief is justified if, and only if, it fits the subject's evidence.^[3] Evidentialists, then, would say that the reason why knowledge is not the same as true belief is that knowledge requires evidence. Opponents of evidentialism would say that evidentialist justification (i.e., having adequate evidence) is not needed to rule out epistemic luck. They would argue that what is needed instead is a suitable relation between the belief and the mental process that brought it about. What we are looking at here is an important disagreement about the nature of knowledge, which will be our main focus further below. In the meantime, we will continue our examination of the JTB analysis.

Let us return to Radford's objection to the belief condition, which we considered above. We are now in a position to discuss further how that objection can be rebutted. Recall that Albert does not take himself to know the answer to the question about the date of Elizabeth's death. He does not because he does not remember having learned the basic facts of British history. Now, it is of course true that he did learn these facts, and is indeed able to recall them. But is this by itself sufficient for knowing them? Philosophers who think that knowledge requires evidence would say that it is not. Albert needs to have evidence for believing that he learned those facts. Until he is quizzed, he has no such evidence. After the quiz, when he is told that most of his answers are correct, he does have the requisite evidence. For once he comes to know that he is able to produce consistently correct answers to the questions he is asked, he has acquired evidence for believing that he must have learned this subject matter at school. This evidence is also evidence for the answers he has given. So at that point, the justification condition is met, and thus (since the other conditions of knowledge are also met) he knows (again) that Elizabeth died in 1603. However, he did not know this before finding out that he must have learned those facts, for at that point his answer to the question lacked justification and thus did not add up to knowledge. Evidentialists would deny, therefore, that Radford has supplied us with a counterexample to the belief condition.^[4]

[From http://plato.stanford.edu/entries/knowledge-analysis/]