Williamson – POP – 7.5.1

Because there are many ideas of interest in section 5 of chapter 7 in The Philosophy of Philosophy (POP) I have decided to split this section among a couple of posts. In this first post I consider the following argument (p. 235) on how traditional skepticism narrows the base of evidence:

  1. Evidence is true (assumption).
  2. The proposition that I have hands (p) is not evidence in a skeptical scenario because it is false (given 1).
  3. According to the skeptic it is contentious that I am not in the skeptical scenario (assumption).
  4. So, it is contentious that p is evidence (2,3).
  5. Therefore, given the Evidence Neutrality (EN) thesis, p is not evidence (EN,4).
  6. Only the proposition that it appears to me that I have hands (p*) is evidence (assumption).
  7. Since both the common sense scenario and the skeptical scenario are consistent with all my evidence I cannot regard the former scenario as more probable than the latter (skeptical conclusion).

The moral of the story for Williamson is that the traditional skeptic can use EN, which is defined and explored in this post, to make it the case that the skeptical scenario cannot be ruled out; thus, it is not the case that I know I have hands or that the external world exists. One problem I have with Williamson’s formulation of the argument is the transition from p to p*. In 2, the proposition p is false because in the skeptical scenario it falsely appears to me that I have hands. My experience of hands is just an induced delusion at the hands of a mad scientist or an architect of The Matrix. In 6, the proposition p* is true. How can p be false because it falsely appears to me that I have hands and p* be true because it appears to me that I have hands? Is not falsely appearing the same as apperances being false? Even though in the skeptical scenario it is true to me that it appears that I have hands I cannot use that psychological fact to satisfy EN because it is contentious that p* is true because it falsely appears to me that I have hands. In the skeptical scenario p* is false as well as p.

Another feature of the argument I find puzzling is the jump from 5 to 6. Even if p is not evidence it is not clear that the only option for finding a proposition that can count as evidence is to resort to psychological claims. Even if, as I explained above, the shift from p to p* fails because p* is also false it is not clear that the only option for looking for true propositions is by turning inward. In a scenario like The Matrix there are glitches in the system that clue people, like Neo, into the fact that reality is not what it seems. A skeptic who uses a Matrix-type scenario can search for evidence in propositions about glitches in the fabric of space-time or computer-coded reality. In The Animatrix these things include:

a section of the house where it’s raining, cans that float in mid-air, doors that go nowhere, and best of all the characters get to slow down time and do leaps and twirls reminiscent of someone who’s jacked into the Matrix knowing how to bend its rules. http://www.thematrix101.com/animatrix/beyond.php

Williamson could make 6 a disjunction: the skeptic must use either a true proposition that exposes the falsehood of appearances or a proposition about appearances. Because propositions about appearances are not true (and only truths count as evidence) this forces the skeptic to use, for example, a proposition that cans float in mid-air (p**) as evidence that the skeptical scenario cannot be ruled out. This makes it the case that no matter which way the skeptic turns she cannot get her conclusion that the common sense scenario and the skeptical scenario are equally probable conditional on one’s evidence. This blocks the use of EN to generate traditional skepticism, which is not a bad thing because it is not clear that traditional skeptics endorse anything like “uncontentious decidability” among a community of inquirers. The traditional skeptic cannot and need not psychologize evidence.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s