UPDATE: I posted this same thing over at Prosblogion – there’s been some discussion there.
We don’t have a complete science of the brain yet, but look at what recent neuro-science has shown. Don’t the recent successes of neuro-science give us good reason to believe that there will one day be adequate evidence for the proposition that the brain is completely scientifically explainable. Shouldn’t we then now think that the brain is completely scientifically explainable?
I think many would find something like the above reasoning plausible. I have to admit I find it plausible, and there are a few other kinds of arguments out there in philosophy that make a similar kind of move.
But here is where I start to get worried. For these strategies to work, something like the following principle must be true.
(1) If S is justified in believing that at some future time S will be justified in believing P, then S is justified in believing P now.
However, this won’t do. I am justified in believing that, at some future time, it will be reasonable for me to believe that my dog is dead. After all, I’m pretty sure my dog isn’t immortal. That doesn’t mean I’m justified in believing that my dog is dead now. We might think there is a quick fix that can get around this.
(1*) If S is justified in believing (at T), both that
i. At some future time it S will be justified in believing P
AND
ii if P is true at some future time, then P is true at T,
then S is justified in believing P at T.
This gets around the dog worry, and would allow the inference in the first paragraph to go through. But suppose I have severe alzheimer’s. My wife tells me that once I am to the point where I can’t remember her anymore, she will insist to my face that she has never met me before. I am justified in believing right now that I will be justified in believing that I never met Sarah. I’m also justified in believing that if I never met Sarah at some future time, then I never met her now. So this revised principle doesn’t work either.
You might think the problem is that in both counter examples the person in question is justified in believing at T that the relevant proposition is false at T.
(1**)
IF S is justified in believing (at T), both that
i. At some future time it S will be justified in believing P
AND
ii. if P is true at some future time, then P is true at T,
AND
iii. S is not justified in believing that P is false at T,
THEN S is justified in believing P at T.
But we can modify the alzheimer’s case, suppose I learn that someone named Sue is going to do the same thing that my wife does. I am given very good reasons to believe that I should right not be skeptical whether or not I have ever met Sue. So, I’m not justified in believing (at T) that I have never met Sue. In this case, I would satisfy the antecedent of (1**), but I don’t think I’m justified in believing (at T) that I never met Sue.
Thoughts?
Hey Andy,
I hope to come back to this either this weekend or next week when I have more time, but I just wanted to ask a question so that both of us could ponder a response of two.
I was just quickly thinking about this, and it seems to me that the first two thought experiments deal with S believing in a proposition in the the subject of the proposition is an object,Q, that S knows personally already. It isn’t a contingent fact that S knows Q at T, and it’s on that that S bases his justification.
But the counterexample with Sue has a contingency factor to it; S doesn’t know whether or not S has met Sue at T. It’s this factor that makes S not justified in believing the consequent at T, that he never met Sue.
Is there possible a clause that could be tacked on that could account for contingency?
-Justin Webb.
Hi Justin,
Consider your claim…
“It isn’t a contingent fact that S knows Q at T”
That means
“It’s necessary that S knows Q at T”
Do you think any of the knowledge claims made in the thought experiments above are necessary truths?
No, I suppose not–perhaps it was my fault for not using a better word other than contingency (because you’re right, it doesn’t seem that S knowing Q at T could be such that S knows Q at T in every possible world; that seems absurd.
I think that I was referring more to a existential claim:
(iv)There exists a Q, such that S is justified in believing that he knows Q at T.
Now, I must note that I do not mean
“There exists a Q, such that S is justified in believing Q at T.”
These two things say different things; the latter refers to S’s justification for Q at T. The former instead refers to S’s justification of S’s ‘knowledge’ at T. In other words, S takes Q, at T, to be justified true belief (with Gettier clause); he’s not figuring out whether or not he knows Q. He takes that he already ‘knows’ Q. What I’m asking is that we take the approach of examining S’s reasons for believing that he knows Q.
Now, would this work? In your dog and your first Alzheimer cases, the instantiation would be your dog and your wife, respectfully, and you have very good evidence in favor of you believing that you know both of them at time, T (namely that they both live with you, you’re married to your wife, etc).
Sue, on the other hand, is such that S isn’t sure if he’s met her or not (S isn’t justified in believing that he knows her at T). He isn’t sure if he’s met Sue or not, and this is what makes the principle unattractive, this factor of uncertainty. If we tack on an existential claim as a fourth clause of the principle:
(1***)
IF S is justified in believing (at T), such that
(i) At some future time it S will be justified in believing P
AND
(ii) if P is true at some future time, then P is true at T,
AND
(iii) S is not justified in believing that P is false at T,
AND
(iv)There exists a Q, such that S is justified in believing that he knows Q at T,
THEN S is justified in believing P at T.
This clause would eliminate the possibility of uncertainty; either S would be justified in believing that he knows Q or he wouldn’t. If we tried to change the example by saying that S is justified in believing that he knows Sue at T, we could say that S is justified in believing P at T, because it would turn out much like it would in the previous counterexamples; S would be justified in believing that he knows Sue, and if this is the case, he could be justified in believing that in the future he would be justified in believing that he’d never met Sue (because he knows that he knows her at T).
If we say that S is not justified in believing that he knows Q at T, then S isn’t justified in believing P at T because S’s uncertainty that he knows Sue at T detracts from him being justified in believing that he will be justified in believing that he has never met Sue.