Thursday, January 25, 2007

Paraphrasing! (Huh, yeah) What is it good for?

Metaphysicians and other philosophers are often uncomfortable with the supposed ontological commitments of many seemingly true ordinary sentences of English. One approach to blunting these commitments is to offer paraphrases of them. I am interested in the details of the approach. In particular, I would like to know whether someone who offers a paraphrase of an ordinary English sentence should take that sentence to be true.

Consider the following English sentence:
(F) There are fictional characters.
Many metaphysicians are uncomfortable with (F)'s apparent commitment to fictional characters. Since the paraphrase approach is intended to help one avoid such commitments, many metaphysicians are likely to offer a paraphrase of (F). Should such philosophers take (F) to be true? If so, then the following claim is true:
(T-F) "There are fictional characters" is true.
However, the following instance of the Tarski bi-conditional also seems to be true:
(I-TB) "There are fictional characters" is true iff there are fictional characters.
However, (F), which is just the claim that one would've thought someone employing the paraphrase strategy would like to avoid, follows from (T-F) and (I-TB). That is, the following argument is valid:
1. "There are fictional characters" is true.
2. "There are fictional characters" is true iff there are fictional characters.
3. Therefore, there are fictional characters.
So, anyone who believes (1) and (2) should also believe that there are fictional characters. Since someone who is concerned with the apparent ontological commitments of (F) would like to reject the claim that there are fictional characters (after all, they are concerned about the apparent ontological commitments of (F) for the very reason that they believe that there are no fictional characters), they need to reject either (1) or (2). But (2) seems pretty obviously true. So, they should reject (1). That is, they should reject the truth of the very sentence that they are offering a paraphrase of. And it seems like such a result can be generalized: Whenever someone hopes to avoid ontological commitment by paraphrasing an ordinary English sentence S, that person should reject the truth of S.

Wednesday, January 24, 2007

Partless Hotdogs

So none of the following views of persistence is committed to any particular view of time: endurantism, perdurantism, and exdurantism. But is there a coherent version of Partless Hotdog view that is presentist?

Tuesday, January 23, 2007

Green is the Color

A while ago I read this post on Weatherson's blog. When I first saw Weatherson's powerpoint slides I thought "wow, that's kind of wierd." But, recently, I looked over more "color illusions" here and here. When I saw the spiral green and blue on the first of the sites linked to in the last sentence, I though "No way is that an illusion". I decided that any theory of color that entails that the green and blue spiral is an illusion must be a false view about color. I then came up with a rough thesis that would not have that unwanted consequence. Unfortunately, I discovered that Daniel Nolan presented roughly the same thesis in his comments on Weatherson's original post. In spite of that fact, I am going to talk about the thesis a bit any way and consider the best objection that I have come up with to that thesis.

The thesis is that, roughly, the color of an object sometimes depends on the things going on around the object. It might be put as a supervenience thesis. For example, perhaps the color of an object supervenes on the topological and geometric properties of that object and of the things nearby that object.

Thus, although the geometric and topological features that result of one of the spirals in the picture that has inspired me are roughly the same as the features in the other spiral, it seems that those featrues are slightly different in the surrounding objects. This is what makes one of the spirals green and the other one blue. Since the colors depend on the surrounding objects, we cannot demonstrate that they are the same color by covering up the surrounding area (as is often done). When we cover up things around the object, we change the color of the object.

Here is an objection, inspire by a conversation with Andrew a few days ago. Suppose we have one of our spiral pictures. We also have a wall situated several feet away from the spiral picture. The wall has holes in it so that an oserver on the other side of the wall can see the spirals but cannot see the stuff surrounding the spirals. Such an observer, the objection goes, would see the colors as the same. But an observer on the other side of the wall, that is, an observer who can see both the spirals and their surroundings, would see them as two different colors. One might think that we should say that the spirals are the same color (to the first observer) but different colors (to the second observer). But no two spirals can both be the same color and different colors at the same time. So, the view in question is incorrect.

Here are the responses that I am considering:

1. The first observer is just mistaken. Since the wall is partially blocking his view, he doesn't have the relavent information for determining the true colors of the sprials.
2. The first observer will in fact see the sprials as two different colors (this can be confirmed by expirment). This might be the case if the cause of the different colors observed is some kind of interference between the light waves bouncing off the spirals and the light waves bouncing off the surroundings. The interference will have already taken place before the light waves from the spirals travel through the holes in the wall. So, the first observer will in fact see the colors as different. This response will, of course, be subject to empirical confirmation or refutation.
3. Both observers are correct. One object (such as the spiral) can in fact be two different colors at the same time.

I like the first response best and the last response least. So, that is what I have been thinking about. What do you guys think?