Wednesday, October 7, 2009

Objections to Epistemological Disjunctivism

Let's say that epistemological disjunctivism is the view that in case 1 you'll have more evidence/reasons than in case 2 for your perceptual beliefs:

C1: It looks to S as if p and that's because S's experience is veridical.
C2: It looks to S as if p and that's because S is hallucinating.

I think that in C1, p is part of S's evidence as a result of S's experience but I don't think that p is part of S's evidence in C2. Various objections have been raised against epistemological disjunctivism, here I want to discuss Conee's objections from, "Disjunctivism and Anti-Skepticism".

Conee has argued that nothing, not even the factive mental states that McDowell thinks we are in when we perceive p to be the case, could confer upon us the sorts of epistemic benefits by which we have better evidence or reasons than we have in the bad case. First, he says that a subject who perceives p to be the case and believes p to be the case is not more reasonable than a subject who undergoes a subjectively indistinguishable hallucination and ends up believing the same thing.

That seems reasonable enough, but it also seems irrelevant. McDowell will say that factive reasons give us better reasons to believe than hallucinations will and it is controversial whether it is right to say that two subjects are equally reasonable in believing what they do only if their reasons are equally good. It seems that someone can be no less than perfectly reasonable in acting wrongly, provided that their conduct can be excused. If the point of offering an excuse is to uphold
someone’s rationality or character in spite of the fact that they acted against an undefeated reason and we succeed in excusing their conduct by showing that they are just as reasonable or responsible as someone who, say, acts rightly, then intuitions about what is reasonable are not a good way to test claims about the comparative strength or goodness of reasons.

Conee recognizes that some will distinguish between judgments of reasonableness and claims about reasons, so he offers this second criticism.


The Defeat Principle: X’s justification for a belief is not stronger than Y’s justification for the same belief, if their respective
justifications are prone to being equally well defeated by the same defeaters.

He observes that if some subject perceived a table and another subject had a hallucinatory experience indistinguishable from this first subject’s experience, the justification these subjects had for believing that there was a table before them would be defeated to an equal degree if told by a trustworthy person that they were hallucinating. He concludes:
"The assumption that the table and its rectangularity are directly manifested by the perception, and not by the hallucination, does not affect the capacity of the testimony to defeat. As this testimony example also illustrates, some defeaters of the
justification would have true content in the hallucination case, and untrue content in the perception case. But this difference also does not affect their capacity to defeat the respective justifications. Thus, The Defeat Principle provides another way to see that the disjunctivist assumption of perceptual directness implies no justificatory advantage."

While I agree that the testimony could defeat the justification these subjects have, I don’t think this tells us much about the justification provided by veridical experience and the justification provided by hallucination.

Suppose my justification for borrowing the neighbor’s car without permission is to drive someone to the hospital because they are in need of immediate medical attention. Your reason for borrowing your neighbor’s car without permission is to drive someone to a restaurant because they are in need of immediate romantic attention. If we are then both commanded by the
gods to return our cars, our justifications are both equally defeated but it seems that mine is better than yours.

Of course, this is about reasons for action, but we can come up with examples of reasons for belief that show that the Defeat Principle is unsound. Suppose God told me that my crystal ball will tell me who will win the derby correctly 99 times out of 100 and God tells you that your crystal ball will tell you who will win the derby correctly 87 times out of 100. My ball says that Sad Clown will win. Your ball says Bride of the Fox will win. The paper reports that Butternut Squash won the race. Before we read the paper, my justification was better than yours. I think after we read the paper our justifications are equally defeated.

We should consider one last example. It seems plausible that experience gives us reasons to believe. It seems plausible to say that experience gives us reasons to believe beyond those that introspection provides. Suppose I have the sort of conscious experience in which it looks to me as if p. Suppose you have a conscious experience indistinguishable from mine. I suppose that introspection and some background beliefs would give you some evidence for beliefs about the external world, but I would think that these reasons are different from the reasons provided by experience and that they are typically worse than the reasons provided by experience. However, if the gods were to tell us that our experiences are not veridical, our beliefs about the external world would presumably be defeated and defeated to the same degree. According to the Defeat Principle, if this is true, I was either wrong to say that experience gives us reasons that introspection does not or wrong to say that they were better. I think these examples show that there is something seriously wrong with the Defeat Principle.


Richard said...

The Defeat Principle might be read as talking about the two justifications being "prone to being equally well defeated by" all or by some of "the same defeaters". You argue against the latter view. What if we adopt the former reading?

Clayton said...


Good question. I've been wondering about that myself, but my thoughts on it are too messy to post (in the main post).

I think it's clear that if all it takes is _some_ defeater, the principle is false. It's akin to saying that three of a kind is no better than a pair because both would lose to a flush.

Maybe the principle is true if we read it as follows:
If every potential defeater would defeat J1 and J2, the differences between J1 and J2 won't matter much.

Two responses come to mind.

*Think about the case of experience based reasons for non-inferential perceptual beliefs and introspective based reasons for inferential beliefs about the external world. It might be that these would-be justifications are subject to the same defeaters, but I don't think we should say that the reasons provided by experience are not different and not better than the ones provided by introspection.

** I don't know if Conee is in a position to assert that the defeat principle applies in the way that he thinks it does if it applies only when we can establish that every defeater defeats experience and hallucination equally.

Clayton said...

I'd also point to the difference between merely believing p and knowing p. It seems that all the same defeaters will apply.

Errol Lord said...

This is just to add fuel to the fire, but it seems to me like The Defeat Principle is really bad on the 'by some' reading. This is especially true if we let testimony provide defeaters (it might actually be interesting to drop testimony cases and think about a related principle having to do with non-testimonial defeaters).

That said, here's my preferred testimony case. Albert is a mathematician working to solve a famous, enormously complicated problem. On Tuesday, he finishes what he reasonably believes to be a proof for an affirmative answer to the motivating question. Let's say he has really strong mathematical reasons to think that he's right, and that his belief is justified. He goes home and tells his wife Elsa 'The answer is Yes!' He is obviously a reliable source on such matters, and so she believes him. However, it seems really plausible that he has a lot more reasons to believe that the answer is Yes than she does. The next day, Albert and Elsa get a call from a friend. Their friend informs them that Albert's friend and rival David has proven that the answer is No. The friend assures them that the proof has been carefully scrutinized by a large group of objective mathematicians and they all agree that the proof is correct. It seems like both Albert's and Elsa's beliefs are defeated by this news, but Albert obviously had more reason than Elsa.

Clayton said...


I think that's a nice case.

Two worries.

B vs. K.

This depends upon your view, but suppose S believes p because of fallacious reasoning and then forgets what his basis is for that belief. S' knows p on the basis of sound reasoning. It seems you can set up cases where S and S' will face all the same defeaters but that suggests that K gives no more reason than B. Scepticism!

Variation on the above. Suppose S believes p on the basis of fallacious reasoning but S' believes it on the basis of good reasoning and doesn't forget her reasons. It might be that the belief that S' has is susceptible to every defeater that the beliefs of S faces plus some extra. Knowing less by knowing more!

Alright, i have to run.

Andrew said...

First, I'm a big fan of your blog, keep it up! Second, I'm a bit of a philosophy rookie, so I hope I'm not way off the mark on this.

In your example for disjunctivism, you say S has the same experience in both cases, but in one case her experience happens to be veridical. You say that when the experience is veridical, P is then included in S's evidence. You conclude that S thereby has more evidence in the veridical case than she does in the hallucination case.

My first problem is that I fail to see how "evidence" so construed can mean the same thing as "reasons." If you asked S her reasons for believing P in C1 and again in C2, wouldn't she give the same reasons in both cases?

Second, it seems to me odd to include P itself in S's evidence, especially since C1 and C2 are carefully stated so as to avoid presupposing that S has access to anything beyond how things seem to her. It's as if we are giving some justificatory weight to the extension (for lack of a better word) of her experience, but that seems odd since S is completely unaware of such things.

Consider an example of Dretske's. Suppose (C3) an altimeter shows the altitude to be 30,000 ft. on a plane (at 30,000 ft.). Suppose (C4) the same altimeter shows the altitude to be 30,000 ft. while inside a pressurized chamber (say, at sea-level).

The altimeter's "evidence" is the same in both cases. But on your account it has better evidence or reasons to represent the altitude as 30,000 ft. in C3 because it's "belief" about altitude was caused in the right way. I would say it has the same reasons/evidence in both cases (namely, the atmospheric pressure).