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Vladimir_M comments on Scientific Self-Help: The State of Our Knowledge - Less Wrong

138 Post author: lukeprog 20 January 2011 08:44PM

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Comment author: Vladimir_M 21 January 2011 07:29:12PM 8 points [-]

[the above argument] affirms the consequent;

To be fair, the above commenter only said that this constitutes "weak evidence" in favor of the hypothesis, and deducing mere evidence (as opposed to certainty) by affirming the consequent is correct reasoning. (How strong evidence should be deduced, of course, is another question that depends on the concrete case. But "shokwave" did say "weak.")

Comment author: Anatoly_Vorobey 21 January 2011 07:58:09PM *  0 points [-]

I think that with no further information but only an affirmed consequent, treating it as nontrivial evidence, even "weak"[1], is wrong; you need to say something about alternative hypotheses, even if it's hand-wavy and vague[2]. This is somewhat of a gray area, to be sure, because the "something about alternative hypothesis" part is often taken to be implicitly understood[3]. But I don't think it's implicitly understood in this case that there aren't other, non-evo-psycho, reasonable explanations of peeps hatin' on PUA.

[1] I think that "weak" in normal usage implies "nontrivial", even though theoretically it could be trivial or zero.

[2] "If my theory is correct, the sun will rise tomorrow".

[3] If a physicist says informally "my theory predicted value X, and measurement confirms", they might take it as understood and not say that other competing theories predict a different value. But a paper will make it explicit unless it's already obvious.

Comment author: shokwave 22 January 2011 07:57:08AM 2 points [-]

When I say 'weak evidence', I mean it. If I met one person who had been practicing PUA for six months, and they hadn't had significantly more sex in those six months than in the previous six months (as judged by some method other than self-reporting; probably by asking the person's friends or roommates), that would be stronger evidence that PUA doesn't work.

Comment author: Anatoly_Vorobey 22 January 2011 09:13:55PM 1 point [-]

As I said above, I believe that you're using the phrase "weak evidence" in a non-standard way, essentially violating Grice's Maxim of Quantity. When something is as weak as in this case, people don't call it weak, they call it trivial or negligible or exceedingly weak, or some other term to transmit the idea of just how very weak it is. When people say "weak evidence", they mean that it's definitely not strong or conclusive, but there's nontrivial amount of it, it's not vanishingly small.

Comment author: shokwave 23 January 2011 04:52:55AM 3 points [-]

I do not believe it is non-standard for LessWrong. I admit I'm guilty of tailoring my posts to fit the LessWrong-specific audience.

Comment author: Anatoly_Vorobey 23 January 2011 06:52:27AM -1 points [-]

You're possibly right. I invite you to test your belief by consulting the search for "weak evidence" over LW. This probably sounds snarky, so let me quickly clarify that I don't mean this in the sense "this search confirms I'm right". I looked over the results briefly and saw that roughly half of them use further qualifiers like "astonishingly weak", "very weak", "extremely weak"and so on, which is consistent with what I'd said. But it's also possible that many results use vanilla "weak evidence" to refer to what other results call "extremely/incredibly weak" etc., and then you're right. I looked at a few "vanilla" uses in context and didn't see that, but I didn't look at enough.

Comment author: MartinB 22 January 2011 02:53:47PM 0 points [-]

I think you find more people for who it does not work, than for whom it works. But I doubt this works as evidence that it does not work.

There are many factors that influence success. One would be doing it wrong.

Comment author: shokwave 22 January 2011 03:38:19PM 1 point [-]

But I doubt this works as evidence that it does not work.

Not much, no. But it works as more evidence than people denouncing it. Weak evidence! Weak! Weak.

Comment author: MartinB 22 January 2011 03:45:17PM 1 point [-]

I think I see different requirements for things working that for things not working.

People getting actively angry about something looks like a (weak) indicator that they are afraid there might be something to it. They do not get angry at 9/11 conspiracists, but laugh about them. They do get angry at the other party.

If you have someone trying to do something and be unsuccessful that tells you even less. I would not see it as indicator of not working. It is just no particular evidence.

But maybe I have the notion of what 'weak' means wrong.

Comment author: shokwave 22 January 2011 04:20:33PM 1 point [-]

If you have someone trying to do something and be unsuccessful that tells you even less. I would not see it as indicator of not working. It is just no particular evidence.

It almost has to be evidence; even if it's just evidence that the person isn't doing it right, then you push this case through your prior for how often they do things wrong. Unless your prior is very high, you're still getting half the impact or more of the evidence. Although you could argue from the selection effect of "correct in your expectations of success" that you're almost guaranteed to only notice cases where they are doing it wrong, not cases where it doesn't work (because you don't expect it to work where it won't).

Comment author: RichardKennaway 22 January 2011 04:46:11PM 0 points [-]

But it works as more evidence than people denouncing it.

More evidence than a negative amount? How much is that worth?

Weak evidence! Weak! Weak.

For practical purposes, I regard weak evidence as equivalent to no evidence. It has the value of a penny lying on the road: I do not bother to pick it up. Weak evidence is not worth wasting time on.

Comment author: shokwave 22 January 2011 05:15:15PM 3 points [-]

More evidence than a negative amount? How much is that worth?

Further up in the thread, I claimed that (in cases like these) people denouncing it is weak evidence in favour.

It has the value of a penny lying on the road: I do not bother to pick it up.

Anecdote: I once refused to pick up a small denomination coin (we don't have pennies in Australia anymore). A friend did and promptly discovered it was a penny, from 1938, and worth two dollars to collectors.

On practical matters, though, this is a case where training will greatly decrease effort and time to pick up (more so than for pennies). If you track how much time is spent on picking up pennies and put a value on that amount of time, and then how much money in pennies you have picked up, you will probably find it not worth it. I expect this weak-evidence-picking-up will prove worth it - if it even slightly addresses the common human problem of incorrectly assessing or entirely discounting large amounts of small evidence, it comes out positive for me.

Comment author: wedrifid 22 January 2011 10:47:40PM 1 point [-]

Anecdote: I once refused to pick up a small denomination coin (we don't have pennies in Australia anymore). A friend did and promptly discovered it was a penny, from 1938, and worth two dollars to collectors.

Still not worth it unless you have a personal interest in coins or expect to find or otherwise collect many such coins. (Of course many people would value the experience at more than $2 just for the novelty and the story.)

Comment author: RichardKennaway 22 January 2011 06:07:45PM 0 points [-]

I expect this weak-evidence-picking-up will prove worth it - if it even slightly addresses the common human problem of incorrectly assessing or entirely discounting large amounts of small evidence, it comes out positive for me.

Can you give some examples of that, i.e. where large amounts of small evidence are being badly used?

Comment author: RichardKennaway 27 January 2011 05:03:55PM 0 points [-]

This appears to be) an example of an accumulation of weak evidence badly used, but in the opposite direction. (I say "appears", because I haven't read the article it references, just that LW posting and its comments.)

Probabilities of multiple events are being multiplied without concern for whether they are independent. And that is the basic practical problem with accumulating weak evidence. Look at the vast amount of evidence for the existence of Santa Claus! Even if each story only offers a microbit of evidence....well, no. The stories are not independent of each other. Collectively they prove no more than a handful of them do.

Comment author: MartinB 22 January 2011 02:51:36PM *  1 point [-]

But I don't think it's implicitly understood in this case that there aren't other, non-evo-psycho, reasonable explanations of peeps hatin' on PUA

After adapting to, and talking to people about at least 10 different idea packages(*), not including this one I finally noticed how dislike is not actually a statement about the idea package itself, but about its perceived strangeness. I got negative and even hostile reactions for each of them! So I assume people do not mentally process everything and then come up with a well reasoned debunk. But they more simply just run a diff(self.current_idea_set,new_idea_set) and if it is to far out reply in the negative.

Peeps hate on everything they don't already know.

(*) being vegetarian, being atheist, standard skepticism which includes a few applied topics like homeopathy and astrology, economics, some instantiations of liberty/libertarian ideas and more

[Edit: \_ as recommended in the comment below]

Comment author: wedrifid 24 January 2011 07:36:10AM 3 points [-]

diff(self.currentideaset,newideaset)

Need to escape the underscores.

diff(self.current\_idea\_set,new\_idea\_set)

diff(self.current_idea_set,new_idea_set)

Comment author: Anatoly_Vorobey 22 January 2011 08:50:37PM 2 points [-]

I understand your frustration, but the PUA case is different: you get lots of people denouncing it who do not as a rule denounce lifestyles very different from their own. Including, for example, some LW members.

BTW, if all the people around me reacted with hostility to unfamiliar ideas, I would, first of all, try to rule out myself as a factor (e.g. maybe I'm annoyingly preachy w/o knowing it?), and if that didn't clear things up, look for better people. Well, actually, I don't know if I'd do that, but I'd like to think I would.