In chapter 10, the antirealism or verficationism shines through strongly. Whereas previously Ludlow noted that we tend to evaluate claims about the past or future based on current evidence, he now seems to say that claims about the past or future are really claims about this evidence (in which case, it's not really evidence except in the trivial sense where we count something as evidence for itself). This, of course, is an unargued leap that he seems to take without being aware of it - if one is to be a presentist, there are a number of ways of grounding past or future truths other than simply in the evidence for such truths. Perhaps Ludlow's linguistic discussion is supposed to provide some such evidence, but it seems to me inconclusive at best, a confusion of assertibility conditions and truth conditions that one would only expect if one were already persuaded of some kind of antirealism.
Indeed, the move seems to be completely unwarranted unless one has already ruled out the alternatives or are assuming some kind of verificationism about meaning. But then it is hard to see how we can rule out many similar, obviously bad moves (notice a pattern developing in this book?). We might, for instance, note that we evaluate claims about other people or places based on personal, spatially proximate evidence. If we follow Ludlow, we would have to conclude that claims about other people or places are just claims about evidence internal to me or where I am at. But this seems to me to be clearly false - solipsism just isn't a viable option. Perhaps someone may object that the evidence we consider can be located in other persons than me or places than the one I am at. It's just mediated by more proximate events, objects or processes. But then we could give exactly the same answer for time - we can be, for instance, in possession of temporally remote evidence about stars via current light processes now reaching the earth from these stars. The same thing goes for fossils, which interestingly, Ludlow thinks are really what sentences purportedly about dinosaurs are really about. But that's just crazy (darn it!).
The main problem Ludlow deals with in this chapter has to do with inferences like the following:
(2)
I am hungry.
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Next Tuesday it will be true that I was hungry.
Now, it might be the case that all evidence for today's hunger disappears by next Tuesday. But then, in that case, it will not be true then that I was hungry today. Ludlow discusses two ways out of this. The first is to say, for instance, that a future tense version of a sentence is true iff the sentence in the present tense is true. So even though there will be no evidence for my hungriness Tuesday, the prediction of future truth is still true. Even though at that later time it ends up not true that I was hungry. This is a pretty weird way out and not very plausible.
The second alternative is to say that the content of my sentences changes over time. So the above inference is going to work even though the evidence for the premise will be long gone because the words purportedly ascribing hungriness to myself change in meaning. But we have no idea what meaning they will take on later, nor for that matter what meaning they had previously. We may, however, not be able to get out of the first strategy here. After all, the proposition that next Tuesday it will be the case that I was hungry seems to follow from the proposition that I am hungry. Since it doesn't make any sense to speak of propositions changing their contents (since, presumably, propositions just are certain sorts of contents), explaining the inference in cases of evidence loss cannot rely on this second strategy. So it looks like Ludlow is going to have to be faced with taking the first alternative after all, which doesn't seem like a good idea.
The main issue behind all of this is whether we can "lose" facts about the past - whether past facts about people or places or events or whatever can simply disappear from reality. And that just seems implausible. The past, whatever else we may say about it, seems firm and fixed and not subject to erasure. Intuitively, this kind of change doesn't seem possible. Despite claims for presentist views that they are common sense, the issues brought up in this chapter I think show that it is indeed quite far from it (or at least Ludlow's version is), Ludlow's protests to the contrary.
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