Theory of Knowledge
Fall 2006
Lecture Notes: Evidentialism

I. Introduction

Some preliminary comments. Some review of ideas previously discussed.

1) Epistemic justification is an evaluative notion applied to beliefs and other cognitive attitudes. Other things, like actions or policies, can be justified as well. But epistemic justification attaches to these attitudes alone.

2) Epistemic justification is the sort of justification that is an important necessary condition for knowledge. Beliefs may also be evaluated in non-epistemic ways. Eg., you might have a practical reason for having a belief - if I'll give you a lot of money if you believe a certain thing, then you might have a sort of justification for believing it. But that's not epistemic justification. Epistemic justification is justification that has to do with truth and knowledge. This should help to get us to focus on the right concept. The key idea is that the fact that I will benefit from believing something has nothing whatever to do with whether I know it to be true, and thus has nothing to do with whether I am epistemically justified in believing it.

3) It is relatively easy to provide good clear examples of beliefs that are justified and others that are unjustified. These initial evaluations may be revised upon further reflection, but they provide a good starting point for discussion.

4) A belief can be epistemically justified even if it is false.

5) Supervenience: See text, p. 40-1. This idea is briefly explained in the text. It’s important. The main idea is that evaluative properties - such as being justified, or reasonable - depend on (or supervene) on other, descriptive properties. Similar things hold of other evaluative properties, such as being morally good, being an excellent paper (or painting), etc. Differences in the evaluative properties depend on differences in these other properties.

Note well: although other philosophers we’ll read may not say much about supervenience, almost all would agree that evaluative epistemic properties supervene on these other, non-evaluative, descriptive properties. In effect, the differences are over which properties epistemic justification supervenes on.

Another thing to note: the point is not that epistemic properties, like being justified, are in any way inferior too, less clear than, or less “real” than these other properties. It’s just that they are dependent properties. By explaining what descriptive facts justification supervenes on, you can get some account of how it is tied down to the world.

6) It’s important to distinguish being justified from being able to show or prove that one is justified. Children know stuff. So they have justified beliefs. But they might be unable to show anyone that they are justified.

7) We will discuss several views about epistemic justification. They fall into two main categories: evidentialist theories and non-evidentialist theories. The former make reasons, or evidence, the heart of justification. The latter make something else - something like functioning in the right way - central. Non-evidentialist theories are best seen as recent innovations. Time permitting, we’ll discuss:

Evidentialist Theories:
A. Strong Foundationalism
B. Coherentism
C. Modest Foundationalism

Non-evidentialist Theories
A. Causal Theory
B. Reliabilism
C. Truth Tracking
D. Proper Functionalism

8) Remember: we are assuming the standard view to be true as we go through this section. If an account of justification sets standards that no one can meet, it is, therefore, not a suitable spelling out of the standard view.

II. Evidentialism

This is not so much a theory as it is a view about the general nature of an adequate theory. It says that justification is entirely a matter of evidence. Evidentialists can differ about what evidence is, how evidence manages to support beliefs, and other details. Some key ideas:

1) The evidence in question is always the evidence a particular person has at a particular time. At any time, what’s justified for you is what is supported by the evidence you now have. Helpful to consider a sentence uttered by a detective hunting for clues about a crime, “There’s evidence about this crime. I may already have it - right here in this pile of paper.” Different use of the word evidence. The meaning in evidentialism is more like “reason”.

2) Evidence can include sensory experiences, memories (or apparent memories), possibly rational insight (evidence comes from the ability simply to see that something is true). [Not all evidentialists seem to agree with this. Some say that what can support a belief is only another belief.]

3) It’s one’s total evidence that matters.

4) I’m happy to restate the thesis as a thesis about what one ought to believe.

5) Obj. 1: DeRose, Philosophy and Phenomenological Research, May 2000. See pp. 697-8, example about Henry. Henry has some good reasons to believe P, but he believes P on the basis of basis of some other lousy reasons. Evidentialism has the wrong result: it implies that he’s justified. DeRose’s claim: Henry is not believing as he ought. But his belief does fit his evidence. So, evidentialism gets the case wrong.

Reply: Well-foundedness is believing on the basis of good evidence. You can have evidence (even in our sense) but not believe for that reason. Henry’s belief is not well-founded. But he is believing the proposition he ought to be believing.

6) Obj. 2: See DeRose, p. 699. (See the epistemic irresponsibility objection in the text.) See the Get the Evidence principle in the text.

Reply: I think that this is false. There are times when you should get more evidence, but you also should believe the proposition in the meantime. The head of the FDA may have good reason to believe that a drug is safe and effective, yet also have an obligation to require more studies that will produce additional evidence.

I take the following to conclusively establish the point: suppose that you have good evidence for P, but you should get more evidence about it, since it is so important. What should you think the new evidence will support? Clearly - P. We can develop this more precisely, applied to the Movie Times example from the text:

1. It is reasonable for the professor to believe that the newspaper will say that the movie begins at 8:00.

2. If (1) is true, then it is reasonable for the professor to believe that the movie begins at 8:00.

3. So, it is reasonable for the professor to believe that the movie begins at 8:00.

4. If (3) is true, then what’s reasonable to believe does not depend on whether one should get additional evidence (i.e., the Get the Evidence principle is false).

5. The Get the Evidence principle is false.

In defense of (1): suppose he didn’t have the paper at hand? Surely (1) would be true then. But it is absurd to think that this changes when he gets the paper.

In defense of (2): to deny this requires thinking that he has reason to think that the paper is wrong. But he definitely has no such reason.

In defense of (4): this in effect just says that what’s true in this case generalizes to other cases in which one could, or even should, get more evidence. Note: GEP does not apply to cases in which one does not already have evidence supporting the conclusion.

7) Obj. 3: A person gets a message entitled “An objection to your theory.” She immediately throws away the message, thereby avoiding unpleasant evidence. Evidentialism implies that she remains justified in believing her theory (assume she was justified to begin with). But this seems wrong.

Reply: receiving the message with that title is in itself evidence against the theory. So she should factor that in. It might be enough to make her belief unjustified, depending upon the details of the case. But evidentialism is neutral on whether she should look at the message. It is professionally irresponsible not to look at it (most likely). But that’s another matter