JonathanLivengood

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Pascal's Muggle: Infinitesimal Priors and Strong Evidence

If the AI actually ends up with strong evidence for a scenario it assigned super-exponential improbability, the AI reconsiders its priors and the apparent strength of evidence rather than executing a blind Bayesian update, though this part is formally a tad underspecified.

I would love to have a conversation about this. Is the "tad" here hyperbole or do you actually have something mostly worked out that you just don't want to post? On a first reading (and admittedly without much serious thought -- it's been a long day), it seems to me that this is where the real heavy lifting has to be done. I'm always worried that I'm missing something, but I don't see how to evaluate the proposal without knowing how the super-updates are carried out.

Really interesting, though.

What do professional philosophers believe, and why?

Ah, I see that I misread. Somehow I had it in my head that you were talking about the question on the philpapers survey specifically about scientific realism. Probably because I've been teaching the realism debate in my philosophy of science course the last couple of weeks.

I am, however, going to disagree that I've given a too strong characterization of scientific realism. I did (stupidly and accidentally) drop the phrase "... is true or approximately true" from the end of the second commitment, but with that in place, the scientific realist really is committed to our being able to uniquely determine by evidence which of several literal rivals we ought to believe to be true or approximately true. Weakening to "most cases" or "many cases" deflates scientific realism significantly. Even constructive empiricists are going to believe that many scientific theories are literally true, since many scientific theories do not say anything about unobservable entities.

Also, without the "in every case," it is really hard to make sense of the concern realists have about under-determination. If realists thought that sometimes they wouldn't have good reasons to believe some one theory to be true or approximately true, then they could reply to real-life under-determination arguments (as opposed to the toy examples sometimes offered) by saying, "Oh, this is an exceptional case."

Anyway, the kinds of anti-realist who oppose scientific realism almost never deny that tables exist. (Though maybe they should for reasons coming out of material object metaphysics.)

What do professional philosophers believe, and why?

We do pretty well, actually (pdf). (Though I think this is a selection effect, not a positive effect of training.)

What do professional philosophers believe, and why?

I'm guessing that you don't really know what anti-realism in philosophy of science looks like. I suspect that most of the non-specialist philosophers who responded also don't really know what the issues are, so this is hardly a knock against you. Scientific realism sounds like it should be right. But the issue is more complicated, I think.

Scientific realists commit to at least the following two theses:

(1) Semantic Realism. Read scientific theories literally. If one theory says that space-time is curved and there are no forces, while the other says that space-time is flat and there are primitive forces (so the two have exactly the same observational consequences in all cases), then the realist says that at most one of the two is true.

(2) Epistemic Realism. In every case, observation and experimentation can provide us with good epistemic (as opposed to pragmatic) reasons to believe that what some single theory, read literally, says about the world.

Denying either of these leads to some form of anti-realism, broadly construed. Positivists, instrumentalists, and pragmatists deny (1), as Einstein seems to have done in at least two cases. Constructive empiricists deny (2) in order to keep a commitment to (1) while avoiding inflationary metaphysics. Structural realists deny one or both of these commitments, meaning that they are anti-realists in the sense of the question at stake.

Meetup Interest Probe: Urbana-Champaign, Illinois

Are the meetings word of mouth at this point, then? When is the next meeting planned?

Meetup Interest Probe: Urbana-Champaign, Illinois

I have had some interest, but I never managed to attend any of the previous meetups. I don't know if I will find time for it in the future.

A reply to Mark Linsenmayer about philosophy

That question raises a bunch of interpretive difficulties. You will find the expression sine qua non, which literally means "without which not," in some medieval writings about causation. For example, Aquinas rejects mere sine qua non causality as an adequate account of how the sacraments effect grace. In legal contexts today, that same expression denotes a simple counterfactual test for causation -- the "but for" test. One might try to interpret the phrase as meaning "indispensable" when Aquinas and other medievals use it and then deflate "indispensable" of its counterfactual content. However, if "indispensable" is supposed to lack counterfactual significance, then the same non-counterfactual reading could, I think, be taken with respect to that passage in Hume. I don't know if the idea shows up earlier. I wouldn't be surprised to find that it does.

A reply to Mark Linsenmayer about philosophy

I'll say it again: there is no point in criticising philosophy unless you have (1) a better way of (2) answering the same questions.

Criticism could come in the form of showing that the questions shouldn't be asked for one reason or another. Or criticism could come in the form of showing that the questions cannot be answered with the available tools. For example, if I ran into a bunch of people trying to trisect an arbitrary angle using compass and straight-edge, I might show them that their tools are inadequate for the task. In principle, I could do that without having any replacement procedure. And yet, it seems that I have helped them out.

Such criticism would have at least the following point. If people are engaged in a practice that cannot accomplish what they aim to accomplish, then they are wasting resources. Getting them to redirect their energies to other projects -- perhaps getting them to search for other ways to satisfy their original aims (ways that might possibly work) -- would put their resources to work.

A reply to Mark Linsenmayer about philosophy

That is being generous to Hume, I think. The counterfactual account in Hume is an afterthought to the first of his two (incompatible) definitions of causation in the Enquiry:

Similar objects are always conjoined with similar. Of this we have experience. Suitably to this experience, therefore, we may define a cause to be an object, followed by another, and where all the objects similar to the first are followed by objects similar to the second. Or in other words where, if the first object had not been, the second never had existed.

As far as I know, this is the only place where Hume offers a counterfactual account of causation, and in doing so, he confuses a counterfactual account with a regularity account. Not promising. Many, many people have tried to find a coherent theory of causation in Hume's writings: he's a regularity theorist, he's a projectivist, he's a skeptical realist, he's a counterfactual theorist, he's an interventionist, he's an inferentialist ... or so various interpreters say. On and on. I think all these attempts at interpreting Hume have been failures. There is no Humean theory to find because Hume didn't offer a coherent account of causation.

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