bryjnar

Karma: 914

bryjnar Mar 1, 2013, 2:08 AM
−1 points
in reply to: whpearson’s comment on: Constructive mathemathics and its dual
Constructivist logic works great if you interpret it as saying which statements can be proven, or computed, but I would say it doesn’t hold up when interpreted as showing which statements are true (given your axioms). It’s therefore not really appropriate for mathematics, unless you want to look at mathematics in the light of its computational or proof-theoretic properties.

bryjnar Mar 1, 2013, 2:06 AM
0 points
in reply to: passive_fist’s comment on: Constructive mathemathics and its dual
Dialethists requires paraconsistent logic, as you have to be able to reason in the presence of contradictions, but paraconsitent logic can be used to model other things than truth. For example, constructive logic is often given the semantics of showing what statements can be proven, rather than what statements are true. There are similar interpretations for paraconsistent logic.

OTOH, if you think that paraconsistent logic is the correct logic for truth, then you probably do have to be a dialethist.

bryjnar Feb 8, 2013, 4:18 AM
1 point
in reply to: JMiller’s comment on: Confusion about Normative Morality
That’s pretty weird, considering that so-called “sophisticated” consequentialist theories (where you can say something like: although in this instance it would be better for me to do X than Y, overall it would be better to have a disposition to do Y than X, so I shall have such a disposition) have been a huge area of discussion recently. And yes, it’s bloody obvious and it’s a scandal it took so long for these kinds of ideas to get into contemporary philosophy.

Perhaps the prof meant that such a consequentialist account appears to tell you to follow certain “deontological” requirements, but for the wrong reason in some way. In much the same way that the existence of a vengeful God might make acting morally also selfishly rational, but if you acted morally out of self-interest then you would be doing it for the wrong reasons, and wouldn’t have actually got to the heart of things.

Alternatively, they’re just useless. Philosophy has a pretty high rate of that, but don’t throw out the baby with the bathwater! ;)

bryjnar Jan 24, 2013, 3:05 AM
2 points
on: Right for the Wrong Reasons
I agree that “right for the wrong reasons” is an indictment of your epsitemic process: it says that you made a prediction that turned out correctly, but that actually you just got lucky. What is important for making future predictions is being able to pick the option that is most likely, since “being lucky” is not a repeatable strategy.

The moral for making better decisions is that we should not praise people who predict prima facie unlikely outcomes—without presenting a strong rationale for doing so—but who then happen to be correct. Amongst those who have made unusual but successful predictions we have to distinguish people who are reliably capable of insight from those who were just lucky. Pick your contrarians carefully.

There’s a more complex case where your predictions are made for the “wrong” reasons, but they are still reliably correct. Say you have a disorder that makes you feel nauseous in proportion to the unlikeliness of an option, and you habitually avoid options that make you nauseous. In that case, it seems more that you’ve hit upon a useful heuristic than anything else. Gettier cases aren’t really like this because they are usually more about luck than about reliable heuristics that aren’t explicitly “rational”

bryjnar Jan 6, 2013, 2:05 AM
3 points
on: Harsanyi’s Social Aggregation Theorem and what it means for CEV
Great post! I wish Harsanyi’s papers were better known amongst philosophers.

bryjnar Jan 6, 2013, 2:00 AM
12 points
in reply to: Qiaochu_Yuan’s comment on: Pigliucci’s comment on Yudkowsky’s and Dai’s stance on morality and logic
Mainstream philosophy translation: moral concepts rigidly designate certain natural properties. However, precisely which properties these are was originally fixed by certain contingent facts about the world we live in and human history.

Hence the whole “If the world had been different, then what is denoted by “morality” would have been different, but those actions would still be immoral (given what “morality” actually denotes)” thing.

This position is sometimes referred to as “sythetic ethical naturalism”.

bryjnar Jan 6, 2013, 1:47 AM
7 points
0
on: Second-Order Logic: The Controversy
I’m still worried about the word “model”. You talk about models of second-order logic, but what is a model of second-order logic? Classically speaking, it’s a set, and you do talk about ZF proving the existence of models of SOL. But if we need to use set theory to reason about the semantic properties of SOL, then are we not then working within a first-order set theory? And hence we’re vulnerable to unexpected “models” of that set theory affecting the theorems we prove about SOL within it.

It seems like you’re treating “model” as if it were a fundamental concept, when in fact the way it’s used in mathematics is normally embedded within some set theory. But this then means you can’t robustly talk about “models” all the way down: at some point your notion of model bottoms out. I don’t think I have a solution to this, but it feels like it’s a problem worth addressing.

bryjnar Jan 4, 2013, 11:26 AM
5 points
on: My Best Case vs Your Worst Case
It’s like the opposite of considering the Least Convenient Possible World; the Most Convenient Possible World! Where everything on my side turns out as well as possible, and everything on yours turns out as badly as possible.

bryjnar Jan 4, 2013, 11:23 AM
3 points
on: Interpersonal and intrapersonal utility comparisons

I’m pretty sure that the idea of the previous two paragraphs has been talked about before, but I can’t find where.

It’s pretty commonly discussed in the philosophical literature on utilitarianism.

bryjnar Jan 3, 2013, 11:34 PM
8 points
on: Can infinite quantities exist? A philosophical approach
I think most of this worrying is dissolved by better philosophy of mathematics.

Infinte sets can be proven to exist in ZF, that’s just a consequence of the Axiom of Infinity. Drop the axiom, and you can’t prove them to exist. You’re perfectly welcome to work in ZF-Infinity if you like, but most mathematicians find ZF to be more interesting and more useful. I think the mistake is to think that one of these is the “true” axiomatization of set theory, and therefore there is a fact of the matter over whether “infinite sets exist”. There are just the facts about what is implied by what axioms.

If you’re worried about how we think about implication in logic without assuming set theory, perhaps even set theory with Infinity, then I agree that that’s worrying, but that’s not particularly an issue with infinity.

Then, on the other hand, you might wonder whether some physical thing, like the universe, is infinite. That’s now a philosophy of science question about whether using infinite sets or somesuch in our physical theories is a good idea. Still pretty different.

Aside: your specific arguments are invalid.
- The indistinguishability argument, regardless of whether it’s good in principle, is incorrect. For infinite X, X and X’=X \union {x} are distinguishable in ZF. For one thing, X’ is a strict superset of X, so if you want a set (a “property”) that contains X but not X’, try the powerset of X. I’m not really sure what else you mean by “indistinguishability”.
- In the relative frequency argument you do limits wrong. It can be the case that lim f(x) and lim g(x) are both undefined, but that lim f(x)/g(x) is fine.

bryjnar Jan 1, 2013, 2:41 AM
1 point
on: Three kinds of moral uncertainty
This definitely seems to be a post-metaethics post: that is, it assumes something like the dominant EY-style metaethics around here (esp the bit about “intrinsic moral uncertainty”). That’s fine, but it does mean that the discussion of moral uncertainty may not dovetail with the way other people talk about it.

For example, I think many people would gloss the problem of moral uncertainty as being unsure of which moral theory is true, perhaps suggesting that you can have a credence over moral theories much like you can over any other statement you are unsure about. The complication, then, is calculating expected outcomes when the value of an outcome may itself depend on which moral theory is true.

I’m not sure whether you’d class that kind of uncertainty as “epistemic” or “intrinsic”.

You could also have metaethical uncertainty, which makes the whole thing even more complex.

bryjnar Dec 30, 2012, 6:46 AM
1 point
in reply to: hyporational’s comment on: The Relation Projection Fallacy and the purpose of life
Oh, I see. Sorry, I misinterpreted you as being sceptical about the normal usage of “purpose”. And nope, I can’t give a taboo’d account of it: indeed, I think it’s quite right that it’s a confused concept—it’s just that it’s a confused concept not a confused use of a normal concept.

bryjnar Dec 30, 2012, 2:59 AM
1 point
in reply to: buybuydandavis’s comment on: The Relation Projection Fallacy and the purpose of life
I’d claim that there is a distinct concept of “purpose” that people use that doesn’t entail an agent with that purpose. It may be a pretty unhelpful concept, but it’s one that people use. It may also have arisen as a result of people mixing up the more sound concept of purpose.

I think you’re underestimating people who worry about “ultimate purpose”. You say they “don’t even understand the context”, as opposed to people who “understand the full context of the concept”. I’m not sure whether you’re just being a linguistic prescriptivist here, but if there are a whole bunch of people using a word in a different way to the way it’s normally used, then I’m inclined to think that the best way to understand that is that they mean something different than that, not that they’re idiots who don’t understand the word properly.

bryjnar Dec 30, 2012, 2:52 AM
1 point
in reply to: hyporational’s comment on: The Relation Projection Fallacy and the purpose of life
“What’s the point of that curious tool in your shed?”

“Oh, it’s for clearing weeds.”

The purpose of the tool is to clear weeds. This is pretty underdetermined: if I used it to pick my teeth then there would be a sense in which the purpose of the tool was to act as a toothpick, and a sense in which I was using it for a purporse unintended by its creator, say.

Importantly, this isn’t supposed to be a magically objective property of the object, no Aristotelian forms here! It’s just a feature of how people use or intend to use the object.

bryjnar Dec 28, 2012, 9:01 AM
1 point
in reply to: [deleted]’s comment on: The Relation Projection Fallacy and the purpose of life
+1 nitpickiness.

And Eliezer makes the same mistake in the linked article too ;) Not that it exactly matters!

bryjnar Dec 28, 2012, 9:00 AM
19 points
on: The Relation Projection Fallacy and the purpose of life
If we’re naming fallacies, then I would say that this post commits the following:

The Linguistic Consistency Fallacy: claiming, implicitly or otherwise, that a word must be used in the same way in all instances.

A word doesn’t always mean the same thing even if it looks the same. People who worry about the purpose of life aren’t going to be immediately reassured once you point out that they’re just missing one of the relata. “Oh, silly me, of course, it’s a three-place relation everywhere else, so of course I was just confused when I was using it here”. If you ask people who are worrying about the purpose or meaning of life, “Purpose for whom?”, in my experience they tend to say something like “Not for anyone in particular, just sort of “ultimate” purpose”. Now, “ultimate purpose” may well be a vague concept, or one that we get somehow tricked into caring about, but it’s not simply an example of people making a trivial mistake like leaving off one of the relata. People genuinely use the word “purpose” in different (but related) ways.

That said, the fact that everywhere else we use the word “purpose” it is three-place is certainly a useful observation. It might make us think that perhaps the three-place usage is the original, well-supported version, and the other one is a degenerate one that we are only using because we’re confused. But the nature of that mistake is quite different.

If you think I’m splitting hairs here, think about whether this post feels like a satisfying resolution to the problem. Insofar as I still feel the pull of the concept of “ultimate purpose”, this post feels like it’s missing the point. It’s not that “ultimate purpose” is just a misuse of the word “purpose”, which, by the Linguistic Consistency Fallacy, must be used in the same way everywhere, it’s that it’s a different concept which is, for various reasons, a confused one.

FWIW I think “2-Place and 1-Place Words” is a bit dubious for similar reasons. Both this post and that make the crucial observation that we have this confusing concept that looks like it’s a good concept “partially applied”, but use this to diagnose the problem as incorrect usage of a concept, rather than viewing it as a perhaps historical account of how that confused concept came about.

Like I said, sort of splitting hairs, but it makes all the difference if you’re trying to un-confuse people.

bryjnar Dec 27, 2012, 2:34 AM
0 points
in reply to: moshez’s comment on: Godel’s Completeness and Incompleteness Theorems
By semantics I mean your notion of what’s true. All I’m saying is that if you think that you can prove everything that’s true, you probably have a an overly weak notion of truth. This isn’t necessarily a problem that needs to be “fixed” by being really smart.

Also, I’m not saying that our notion of proof is too weak! Looking back I can see how you might have got the impression that I thought we ought to switch to a system that allows infinite proofs, but I don’t. For one thing, it wouldn’t be much use, and secondly I’m not even sure if there even is such a proof system for SOL that is complete.

bryjnar Dec 26, 2012, 10:54 PM
0 points
in reply to: moshez’s comment on: Godel’s Completeness and Incompleteness Theorems
Absolutely, but it’s one that happens in a different system. That can be relevant. And I quite agree: that still leaves some things that are unknowable even by supersmart AI. Is that surprising? Were you expecting an AI to be able to know everything (even in principle)?

bryjnar Dec 26, 2012, 6:25 AM
0 points
in reply to: crap’s comment on: Ideal Advisor Theories and Personal CEV
They explicitly don’t address that:

Second, it might seem that this approach to determining Personal CEV will require a reasonable level of accuracy in simulation. If so, there might be concerns about the creation of, and responsibility to, potential moral agents.

bryjnar Dec 26, 2012, 6:17 AM
1 point
in reply to: Shmi’s comment on: Ideal Advisor Theories and Personal CEV
Ooookay. The whole “loop” thing feels like a leaky abstraction to me. If you had to do that much work to explain the loopiness (which I’m still not sold on) and why it’s a problem, perhaps saying it’s “loopy” isn’t adding much.

This loses the sight of the original purpose: the evaluating criteria should be acceptable to the original person

I think I may still be misunderstanding you, but this seems wrong. The whole point is that even if you’re on some kind of weird drugs that make you think that drinking bleach would be great, the idealised version of you would not be under such an influence, etc. Hence it might well be that the idealised advisors evaluate things in ways that you would find unaccepable. That’s WAD.

Also, I find your other proposal hard to follow: surely if you’ve got a well-defined utility function already, then none of this is necessary?