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24 August, 2010

Surveys and Thought Experiments

I’m generally sceptical of the value of surveys, as currently conducted by practitioners of ‘experimental philosophy’ as a way of getting clear about what’s going on in philosophically interesting thought experiments. The most systematic reason for this scepticism comes from thinking about what exactly is going on in thought experiments.

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Posted by Brian Weatherson at 7:09 pm


What is Stakes-Sensitive?

There was a fair bit of back and forth in the previous thread on just what us stakes-sensitive folks were claiming to be stakes-sensitive. So I thought I’d list what I thought was stakes-sensitive, and perhaps others who thought there is stakes-sensitivity somewhere can chime in either in comments or on their blogs/sites.

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Posted by Brian Weatherson at 7:01 pm

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Shameless TAR-promotion

If you’re anything like me, you mostly read blogs through RSS feeds, and maybe Twitter links when they are posted. This means you sometimes miss slow developing comments threads. If so, you may not have seen the very interesting thread that developed on the previous post here. So this is just a small post to let you know that thread exists.

I have a number of thoughts on points arising out of that thread, but in the interests of being orderly, and of self-promotion, I’ll post them to new entries on the blog. (Comments are turned off here because you can always post on the previous thread.)

Posted by Brian Weatherson at 7:00 pm

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20 August, 2010

Philosophy in the New York Times

There is a small symposium in the New York Times today about the recent trend in analytic philosophy towards experimental philosophy.

As some of the contributors note, it’s easy to overstate the trend that’s going on here. It’s not that for the 20th Century, philosophers used only armchair methods, and with the dawning of the 21st century they are going back to engaging with the sciences. When I was in grad school in the 90s, it was completely common to rely on psychological studies of all of uses, especially studies on dissociability, on developmental patterns, and on what was distinctive about people with autism or with Capgras Syndrome. And the influence of Peter Singer on work in ethics meant that purely armchair work in ethics was out of the question, whatever one thought of Singer’s conclusions.

This was hardly a distinctive feature of philosophy in south-eastern Australia. Indeed, we were probably more armchair-focussed than contemporary American philosophers. As Ernie Sosa notes in the entry linked above, 20th century metaphysics is shot through with arguments from results in 20th century physics. The importance of objective chance to contemporary nomological theories is obviously related to the role of chance in different branches of physics and biology, and modern theories of it involve a lot of attention to various sciences. And I’ve lost count of the number of debates I’ve been in in philosophy of language where appeal has been made at one stage or other to cross-linguistic data, which is presumably not armchair evidence unless we assume that the person in the armchair knows every human language. So it’s a bit of a stretch to say, as Joshua Knobe does, that in that time “people began to feel that philosophy should be understood as a highly specialized technical field that could be separated off from the rest of the intellectual world.” I’m really not sure which of the great philosophers of the 20th century could be characterised this way. (Perhaps if you included mathematics in philosophy and not the “rest of the intellectual world” you can get a couple of great 20th century philosophers in. But I doubt it would get much beyond that.)

That’s not to say there’s nothing new that’s been happening in the last fifteen years or so. In fact I think there are three trends here that are worth noting.

One purely stylistic, and actually rather trivial, trend is that philosophers are now a bit more inclined to ‘show their workings’. So if I want to rely on Daniel Gilbert’s work on comprehension and belief, I’ll throw in a bunch of citations to his work, and to the secondary literature on it, in part to give people the impression that I know what’s going on here. You won’t see those kind of notes in, say, J. L. Austin’s work. But that’s not because Austin didn’t know much psychology. I suspect he knew much much more than me. But because of very different traditions about citation, and because of differences in self-confidence between Austin and me, his philosophy might look a bit further removed from empirical work.

A more interesting trend is picked up by Ernie Sosa – philosophers are doing a lot more experiments themselves than they were a generation ago. This is presumably a good thing, at least as long as they are good experiments!

The university that Ernie and I work at, Rutgers, has a significant causal role in this. We encourage PhD students to study in the cognitive science department while they are at Rutgers, and many of them end up working in or around experimental work. That’s not to say I’m at all responsible for this – I’m much more sedentary than my median colleague. But many of my colleagues have done a lot to encourage students interested in experimental work.

The third trend, and this one I’m less excited about, is the reliance on survey work in empirical work designed to have philosophical consequences. It seems to me that surveying people about what they think about hard philosophical questions is not a great guide to what is true, and isn’t even necessarily a good guide to what they think. We certainly wouldn’t take surveys about whether people think it should be legal for an Islamic community center to be built around the corner from here to be significant to political theory debates about freedom of religion.

A slightly more interesting result comes from a survey that Matthew Yglesias posted this morning. If you trust Gallup, only 26% of Americans believe in “the power of the mind to know the past and predict the future”. This is a more than a little nuts, at least as interpreted literally. I know that I had blueberries with breakfast, and I can confidently and reliably predict that the Greens will not win the Australian election currently underway. And I know these things in virtue of having a mind, and in virtue of how my mind works. There’s the power of the mind to know the past and predict the future in action!

Of course, the 74% of people who apparently denied that the mind has the power to know the past and predict the future probably don’t really deny that I have these powers. The survey they were asking was about paranormal phenomena generally. And I left off part of the question they were asked. It asked whether they believed in clairvoyance, which they ‘clarified’ as the power of the mind to know the past and predict the future. Presumably at least some of the people who answered ‘no’ (or ‘don’t know’) interpreted the question as not being about the power of the mind to know stuff through perception, memory and inference, but through some more extraordinary method.

It’s in general extremely hard to understand just what qustion people are answering in surveys. And this makes it hard to know how much significance we should place on different surveys. This matters to some live puzzles. For instance, as Jonathan Schaffer recently wrote, there is an “emerging consensus in experimental philosophy, according to which … the magnitude of the stakes does not affect intuitions about knowledge.” (By ‘the stakes’ he means the stakes faced by a person about who we’re asking whether they know that p, when the person has to make a decision to which p is relevant.) This consensus is largely because the experimenters asked subjects whether certain fictional characters, some facing trivial decisions and some facing quite momentous decisions, knew that p, where p is something that would be important in their deliberations. Generally, they didn’t find a difference in the responses.

But there is quite a bit of evidence, including a lot of experimental evidence (PDF), that differences in stakes in this sense really do matter to cognitive states. In particular, what it takes to have settled the question to one’s own satisfaction of whether p is true, depends on what is at stake, and if you ask them the right way, survey respondents agree that it depends on what is at stake. Assuming, as everyone in this debate does, that knowledge requires settling questions to one’s own satisfaction, this means we have empirical evidence that stakes matter to knowledge. What does this mean for the consensus that Schaffer reports? I suspect it means, like in the Gallup survey, that different people are interpreting the survey questions differently, but there are lots of alternative explanations. In any case, I’d want a lot more evidence than surveys though before I overturned a well established result in experimental psychology.

Posted by Brian Weatherson at 10:05 pm


16 August, 2010

Evidence and Probability

Two detectives, D1 and D2, are investigating a murder. In fact, the butler did it. But all the evidence suggests the gardener did it. D1 believes that the butler did it; D2 believes that the gardener did it.

It’s easy enough to describe and evaluate these cognitive states. D1 and D2 have both made judgments. Both of those judgments are about the identity of the murderer. D1’s judgment tracks the truth, but not the evidence. D2’s judgment tracks the evidence, but not the truth.

We can expand this story without many complications. Assume that the evidence about the evidence is not at all misleading. The evidence supports the proposition that the evidence supports the proposition that the gardener did it. D1, as you may expect, believes the evidence supports the proposition that the butler did it, and D2 believes the evidence supports the proposition that the gardener did it.

It’s easy enough to say something about these judgments as well. D1’s judgment tracks neither the evidence nor the facts. D2’s judgment tracks both the evidence and the facts. These judgments are not, in the first instance, about the identity of the murderer. Rather, they are about the epistemic significance of the evidence. So we have a few different arguments, by Leibniz’s Law, that D1’s belief that the butler did it is distinct from his belief that the evidence supports the proposition that the butler did it. And D2’s belief that the gardener did it is distinct from her belief that evidence supports the proposition that the gardener did it.

Things get trickier when the evidence is less one-sided, as the following example shows.

D3 and D4 are investigating whether the chef was an accomplice to the murder. The evidence supports this to degree 0.7. That is, the evidential probability that the chef was an accomplice given the available evidence is 0.7. But the evidence D3 and D4 have suggests that the evidence supports the chef being an accomplice to degree 0.95.

Now some people will say that what I’ve supposed in the previous paragraph is incoherent. That shouldn’t stop us treating it as a supposition. The supposition that there’s a largest prime entails all propositions, but we can sensibly suppose it. More directly, I think there are plenty of examples where something like the previous paragraph could be true. Assume, for example, that D3 and D4 had a rather bad statistics professor in detective school, and this professor told them that a certain statistical method was usable in cases like this, when in fact it was not. Using the method would increase the apparent probability that the chef is the accomplice from 0.7 to 0.95. D3 and D4 aren’t statistics experts, so their evidence suggests that this method works. But in fact, since the professor was wrong, the method doesn’t really increase the likelihood that the chef was the accomplice.

Let p be the proposition that the chef was the accomplice, and E the evidence D3 and D4 have. Let’s assume, for simplicity, that D3 and D4 have correctly identified E. Then consider the following four attitudes:

  1. D3’s credence of 0.95 in p.
  2. D4’s credence of 0.7 in p.
  3. D3’s belief that E supports p to degree 0.95.
  4. D4’s belief that E supports p to degree 0.7.

State 1 does not track the evidence; state 3 does. So by Leibniz’s Law, states 1 and 3 must be different states. Similarly, states 2 and 4 must be different states.

I’ve been doing quite a bit of work on the evidential significance of cognitive states like states 1 through 4. (Short answer: whatever significance there is will generally be screened by the evidence the state is based on.) I’ve usually called this work on the evidential significance of judgments. I think this is an OK bit of terminology, though it’s a bit tricky to call states 1 and 2 judgments. After all, we normally think of judgments as having propositional content, and the content of the judgment characterising the state. But there’s no way to do that with both 1 and 2. If we say that the content of the judgment is p, then we can’t distinguish a state like 1 from a state like 2. (I think that’s not a terrible result, but it is odd.) If we say the content of the judgment is that p is supported by E to a certain degree, then we have no way to distinguish a state like 1 from a state like 3. And we proved in the previous paragraph that they were distinct. If we say the content of the judgment is p, we have to say that judgments come in degrees. If we say that the content of the judgment is a proposition about the force of E, we violate Leibniz’s Law. It’s bad to be illogical, so I adopt the first of these options.

There’s another argument for 1 and 3 being separate states, namely that they have separate contents. But I don’t think that’s overly compelling on its own. After all, it isn’t quite clear what the content of 1 is. In the previous paragraph I argued that it’s p, but that argument rests on the Leibniz’s Law argument. So I think the Leibniz’s Law argument does all the work here.

If D3 says, “Almost certainly, p”, is she expressing state 1 or state 3? I think she could be expressing either of them. That’s to say, “Almost certainly, p” is a reasonable enough way of expressing 1, and a reasonable enough way of expressing 3. In the past I’ve gone on at some length defending broadly cognitive accounts of statements like “Almost certainly, p”, arguing that they must be interpreted as expressions of state 3. But I no longer think there are good arguments for that position.

The main argument for such a position is a variant on the general Frege-Geach argument against expressivism. If we thought that expressions like “Almost certainly, p” only ever expressed states like 1, then we wouldn’t be able to give them truth-conditions (apart from p) and hence we’d have a hard time embedding them in more complex sentences. But if we think that whenever such an expression is, say, the antecedent of a conditional it gets interpreted as having the same meaning as the content of the belief in state 3, we don’t have any problem with explaning embedding. So I now think the force of an utterance like “Almost certainly, p” just varies. Sometimes it expresses a belief about evidential probabilities, and sometimes it expresses a credence.

Posted by Brian Weatherson at 3:21 pm

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14 August, 2010

Studentship at Leeds

The AHRC recently awarded a grant to Elizabeth Barnes, Ross Cameron and Robbie Williams (all at Leeds) to work on metaphysical indeterminacy. This is really great news for Leeds, and for Elizabeth, Ross and Robbie. Well done to all of them!

The grant includes funding for a PhD position, but applications for that position are due within a couple of weeks. The full details for that position are below the fold. Read the rest of this entry »

Posted by Brian Weatherson at 4:53 pm

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