Dec 10: Skepticism
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To do for next class - 1) Read chp. 10; 2) Be a skeptic; 3) Final papers due. |
To do for next class - 1) Nothing! |
Demons and scientists
Our close friend, the evil demon, was first posited by Descartes in his meditations. Descartes supposed the possibility of an evil demon that deceived him into believing that there were physical things, including his own body. Where, in fact, there are no such things and what we perceive is mere appearance. This lead Descartes to pose his famous question: how can we be certain of anything? More recently, the demon has been replaced by scientists but their role as philosophical villains remains the same. Rather than unspecified trickery, scientists rely on high-tech gadgetry to simulate the world around you by directly stimulating your brain. Of course, from your pointed view, nothing has changed; i.e. your perceptions are identical to what they would have been if you were not a brain in a vat. Skeptics argue that there is no possible way for you to determine whether or not you are the victim of an evil demon or a mad scientist. For this reason, you do not know what you normally think you know with certainty. What the strong skeptical claim amounts to, then, is that almost none of our beliefs are justified.
Of course, the extreme skeptic (who believes there's
nothing we can be justified in believing) cannot formulate an
interesting argument for his position since that position
would be as unjustified as everything else. Such positions are
philosophically uninteresting. A more coherent form of skepticism
would have to argue that certain kinds of knowledge are unjustified
whereas others, including the skeptical argument, to enjoy justification.
Standard applications of skepticism focus on empirical knowledge
as being either less justified, or totally unjustified relative
to a priori knowledge. Steup gives us the following schema for
skeptical arguments:
(1) in order to know something it must be justified to degree
N.
(2) that thing (those things) are not justified to degree N.
(3) therefore we do not know that thing.
Why is this form of argument more philosophically interesting than extreme skepticism? (A common ground is established using (1) between skeptic and non-skeptic). Steup takes a simplified version of skepticism as an exemplar. In this case, the skeptic and non-skeptic agree that justification at least to some degree is necessary for knowledge. Then, if the skeptic can establish that the certain kind of knowledge is not at all justified her argument has succeeded. In constructing the argument, the skeptic often presumes the transmissability principle (what is this? (Transmission of justification through entailment)). As well, the skeptic needs some kind of skeptical hypothesis, that is, a claim which is incompatible with standard beliefs but is compatible with the evidence which one has for those beliefs. Then argument of the following form can be constructed and modus tollens will lead us to our conclusion: A&B->C; B; ~C; Therefore, ~A. (See p. 206, re-incarnated by Barry Stroud, 1984). Can you give a concrete example of this kind of argument? Where is the weak point in this argument? (The skeptical claim that you're not justified in denying the skeptical hypothesis).
Anti-skepticism
In arguing against the skeptic, the anti-skeptic is in the weaker position. Why is this? (Because the skeptic need only establish that you are not justified in believing something which is easier to do than to establish that you are justified in believing something. The reason is that being 'not justified' is established either through showing non-justification or justification of the negation of what you want to believe). In other words, skeptics must only show that their reasons for skepticism are at least as good as your reasons for non-skepticism.
One of the more famous anti-skeptical arguments was presented by G.E. Moore. Essentially, Moore claims that the skeptical assertion that "I'm not justified in believing I'm not a brain in a vat" is less credible or reasonable than the proposition that the skeptic wants to deny, such as "I'm justified in believing I'm seeing a blue chair". If we tell the skeptic that there is no reason to believe that the former is at least as reasonable is the latter then she must provide more argument for believing the former. In other words, her argument will be extended, have more premises, and therefore be more open to attack. This particular kind of attack would consider arguments which support the assertion that "I'm not justified in believing I'm not a brain in a vat".
The standard skeptical argument is that since you have the same subjective experience as you would have if you were a brain in a vat you can be no more justified in believing that you aren't such a brain than that you are one. More semantically, this argument can be written as: (1) nothing can reveal the new which situation obtains. (2) if nothing can reveal that do you then you not justified in denying the skeptical hypothesis. (3) therefore you are not justified in denying the skeptical hypothesis. The question, as Steup notes, it is what is meant in the first premise for "reveal". Steup suggests that something is revealed if you have evidence in support of a belief about the situation. So, do we have evidence for which situation obtains? Steup thinks the answer is clearly "yes". He notes that we have no reason to believe a scientist could perform such a technological feat. Perhaps, the claim in (1) is stronger and thus demands that we have conclusive evidence in support of our belief about which situation obtains. Conclusive evidence for a belief must logically guarantee that our belief is true. Of course, our evidence for believing the skeptic is not conclusive in this sense. What is wrong with this argument? In particular, what is wrong with the criteria of conclusive evidence? The problem is that we have conclusive evidence for almost nothing. So, it is "unfair" for the skeptic to expect this from the non-skeptic. In other words, if we retain a consistent notion of justification (one which is presumably weaker than conclusive evidence) the skeptical arguments will fail. In Steup's words, the skeptic has proved her point only if we take justification to be infallible.
Defeasibility
Do you recall what defeasibility has to do with our definition of knowledge? (Knowledge is justified belief that is factually undefeated). So, the skeptic can argue that the skeptical hypothesis factually defeats my evidence for believing that I am not a brain in a vat. Recall, a factual defeater must be a true proposition. Clearly, if the skeptical hypothesis is true the skeptic has won the argument. If the skeptical hypothesis is false then it can't act as a defeater. However, we can no more establish the truth or falsity of the skeptical hypothesis that of its contender. So, suppose the skeptic wishes to assert "it is logically possible that I am a brain in a vat". This is true. However, logical possibility is not strong enough to act as a defeater of its contrary, so this will not play the role the skeptic desires. By strengthening the claim such that it is "probable" that we are brains in vats won't help either since it is false. More in line with the previous section it is likely that the skeptic would assert "I cannot distinguish between the skeptical hypothesis and its antithesis". However, the same ambiguity as for "reveals" will affect our understanding of this sentence. In other words, it is false that we don't have evidence for the non-skeptical hypothesis and it is "of course" true that we do not have conclusive evidence. However, not having conclusive evidence is no threat to justification since justification does not guarantee truth. The arguments we have been considering thus far speak only to the strongest skeptical hypothesis that our knowledge has no justification. However, the skeptic could entertain the weaker claims that we do not have enough justification for believing we are not brains in vats.
To summarize, the skeptic seems to have succeeded in showing us that we do not have infallible knowledge. That is, we are not certain of the existence of the empirical world. However, if we believe it is the skeptics goal to show that our ordinary concept of knowledge is inadequate, she has failed. This is because the ordinary concept of knowledge does not presumed infallible knowledge. In other words, if the skeptic set out to show that our knowledge claims have zero percent justification she has failed. If she set out to show that such claims do not have 100 percent justification she succeeded. However, according to Steup, our ordinary concept of knowledge assumes justification between those two extremes. Steup provides a more technical summary in which he shows that the skeptic, in arguing for a lack of fallible justification, equivocates on the notion of "know".
The argument from error
What is the argument from error? How is a different from the standard skeptical hypothesis? (This argument attempts to attack the possibility of empirical knowledge without bothering with justification). The argument begins by constructing parallels between various situations. We know, as a matter of fact, that we are mistaken in many situations in which we think we have knowledge claims. The skeptic would like to argue that such situations are perfectly analogous to situations in which we have knowledge claims that we don't know we are not mistaken about. In other words, there is nothing about the situation which is relevant to a knowledge claim which can guarantee you are not mistaken. That is, there is no relevant difference between situations when you are mistaken and situations when you are not. The non-skeptic must determine whether is a difference between these two kinds of situations. Steup believes he has accomplished this. How? (By making the difference in question one between the present evidence regarding both situations at once). Essentially what states argument boils down to is this: the difference between situation one and situation two is that in the second situation I have no evidence for being mistaken whereas I now have evidence that I was mistaken in the prior situation. In other words "I have no evidence that I am wrong now". What do you think of his argument? What do you think of his argument that Q2 is the relevant question?
Of course, the skeptic has a rejoinder. What is it? (That the claim was intended to be taken from a third person point of view). Essentially, this is a means of counter-acting in the non-skeptical claim that I know something until I have direct evidence against it. So, we would construct the case in which one proposition is true and another is false even though our subject has equally good evidence for both. The question is now what we would say the subject knows. Steup introduces the example from Tienson of the embezzlers Black and White. Say White is innocent by the evidence for White's innocence identical to that for Black's innocence. Now, even though White is innocent and the detective has evidence for White's innocence we cannot claim the detective knows that White is innocent because of the case for Black. How can the non-skeptic argue against the skeptics example? Can you construct a non-skeptical counter example of your own? What is the form of the non-skeptical counter argument? (skeptic: if A&B->C; A;B; therefore C; non-skeptic:~C;A;B;therefore ~(A&B->C) ). What is going on here? How can one example assert C while the other denies it? The reason is that the truth or falsity of the premises depends on how are a priori understandings of knowledge claims. As Steup notes, this result in a conflict between a general principle posited by the skeptic (A&B->C) any specific knowledge claim judged to be knowledge (C). This brings us back to the kind of conflict G.E. Moore's strategy resulted in. So again, the non-skeptic must show that the reasons for believing C are better than the reasons for (A&B->C). In conclusion, Steup leases for the pragmatic considerations that the risk involved in excepting general principles is generally greater than that for excepting concrete propositions. However, he does not note that general principles promise greater knowledge as well.
Conclusion
That concludes our whirlwind tour of metaphysics and epistemology. Hopefully from this brief introduction, it is evident that both of these subject areas pose the kinds of questions that people spend lifetimes trying to answer. Most importantly, I hope you have learned new ways of thinking about any questions you might encounter. In other words, though you may find the questions posed by philosophers difficult or uninteresting, there is still a valuable methodology which is employed in examining these questions which is generally applicable. Critical thinking is the mainstay of analytic philosophy, which is what we have been practising in this class. Any questions?
To do for next class
1) Nothing!