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wedrifid comments on The Amanda Knox Test: How an Hour on the Internet Beats a Year in the Courtroom - Less Wrong

42 Post author: komponisto 13 December 2009 04:16AM

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Comment author: wedrifid 13 December 2009 05:04:03AM *  6 points [-]

Am I really suggesting that the estimates of eight jurors -- among whom two professional judges -- who heard the case for a year, along with something like 60% of the Italian public and probably half the Internet (and a significantly larger fraction of the non-American Internet), could be off by a minimum of three orders of magnitude (probably significantly more)? That most other people (including most commenters on my last post) are off by no fewer than two?

Your assertion of such a high probability of guilt does not constitute a claim that most other commenters on your last post were off by no fewer than two orders of magnitude. Probability is subjectively objective. There is one correct estimate for you to have given what you know but this is not the same one that others should have. In fact, given that on average the commenters care less about the subject so did less research if they arrived at the same confidence as you then one of you would probably have to be wrong.

The commenters whose estimates were closest to mine -- and, therefore, to the correct answer, in my view -- were Daniel Burfoot and jenmarie. Congratulations to them. (But even they were off by a factor of at least ten!)

The task isn't to guess your password. The task is to assign probability estimates about the state of their timeline of universe. Their universe does not include the state 'it is <some completely arbitrary high probability> probable that Amanda is innocent'.

ETA: I totally agree with your main contentions and found your post both insightful and extremely well written. It is rare to see such well reasoned essays from people who are emotionally entangled with the topic.

Comment author: komponisto 13 December 2009 05:29:42AM 0 points [-]

Serious nitpicking going on here. The whole point of my post is that from the information provided, one should arrive at probabilities close to what I said.

I don't have appreciably more info than many who participated in my survey, and certainly not more than the jury in Perugia.

Comment author: wedrifid 13 December 2009 06:20:10AM *  10 points [-]

Serious nitpicking going on here.

Probability theories and the philosophies thereof are of interest to me and there are a lot of intuitive traps that are easy to fall into.

The whole point of my post is that from the information provided, one should arrive at probabilities close to what I said.

If that is what your point was then I actually disagree with it. I am not comfortable giving odds of 1:999 after looking briefly at two biassed webpages and a wikipedia page that you tell me is fluctuating at the whims of editorial bias. I know damn well I'd be wrong more than once if I did something like that 1,000 times.

Don't forget that "the order, manner, and quantity of browsing will be left up to [them]". It would be quite reasonable for someone to decide to read until a certain level of confidence has been reached. Once you are 99% confident that the poor girl is innocent what do you hope to achieve by marinating yourself in more and more evidence (or, for that matter, the lack of it)?

It would be great if I could go all Liam Neeson and say "if you let her go now, that'll be the end of it. I will not look for you, I will not pursue you. But if you don't, I will look for you, I will find you, and I will kill you." Alas, I do not have any way to efficiently influence the justice system of Victoria or Australia, much less Italy.

(Damn I hate juries. The thought of being at the mercy of a mob of my peers fills me with equal parts fear and outrage. But it isn't my fight. Except in as much as the only path to a justice system I actually trust probably involves FAI.)

Comment author: Morendil 13 December 2009 09:39:40AM 3 points [-]

How about a Truth Machine ?

Comment author: Blueberry 13 December 2009 06:54:21PM 0 points [-]

Wow. That book is really good. Thanks for linking to it!

Comment author: Morendil 13 December 2009 07:02:49PM 0 points [-]

You might also like The First Immortal by the same author.

Comment author: komponisto 13 December 2009 06:35:18AM 1 point [-]

If that is what your point was then I actually disagree with it. I am not comfortable giving odds of 1:999 after looking briefly at two biassed webpages and a wikipedia page that you tell me is fluctuating at the whims of editorial bias. I know damn well I'd be wrong more than once if I did something like that 1,000 times

What if I tried putting it this way: people underestimate the (potential) power of applying rationality techniques as compared with gathering more raw information. It is sometimes possible to be extremely confident about a proposition after an hour of Internet research, even when people who have spent a year "gathering evidence" seem to disagree shaprly.

Comment author: wedrifid 13 December 2009 06:51:01AM *  2 points [-]

What if I tried putting it this way: people underestimate the (potential) power of applying rationality techniques as compared with gathering more raw information. It is sometimes possible to be extremely confident about a proposition after an hour of Internet research, even when people who have spent a year "gathering evidence" seem to disagree sharply.

Totally agree, and that's a point that you explained convincingly in your post. Just so long as I don't have to quantise 'extremely confident' as 0.999. Although given an hour and also given that the lesswrong.com discussion is now part of 'the Internet', I expect I would break the 0.99 mark at least.

Comment author: jpet 14 December 2009 08:05:02AM *  2 points [-]

Serious nitpicking going on here. The whole point of my post is that from the information provided, one should arrive at probabilities close to what I said.

It's not "nitpicking" to calibrate your probabilities correctly. If someone was to answer innocent with probability 0.999, they should be wrong about one time in a thousand.

So what evidence was available to achieve such confidence? No DNA, no bloodstains, no phone calls, no suspects fleeing the country, no testimony. Just a couple of websites. People make stuff up on websites all the time. I wouldn't have assigned .999 probability to the hypothesis that there even was a trial if I hadn't heard of it (glancingly) prior to your post.

[edit: I'm referring only to responders who, like me, based their answer on a quick read of the links you provided. Of course more evidence was available for those who took the time to follow up on it, and they should have had correspondingly higher confidence. I don't think your answer was wrong based on what you knew, but it would have been horribly wrong based on what we knew.]

Comment author: aausch 13 December 2009 05:57:28AM 0 points [-]

It might have been more useful to ask for confidence intervals around probabilities. Maybe that should become the standard around here?

That way, I imagine people who did not care so much about the topic/do as much research, would have had a way to indicate the fact.

Comment author: wedrifid 13 December 2009 06:39:25AM *  4 points [-]

It might have been more useful to ask for confidence intervals around probabilities. Maybe that should become the standard around here?

No! In this context confidence intervals around the probability have no meaning!

I do agree that adding extra information about confidence is important for things like this. It's just that this isn't a case for which confidence intervals (approximately) work. It would make more sense if the probability was a property of the universe itself, then you could establish bounds on where the 'true probability' lies (as discussed with komponisto).

Comment author: saturn 13 December 2009 08:14:51AM *  1 point [-]

No! In this context confidence intervals around the probability have no meaning!

Why can't they be confidence intervals around the probability after doing [some amount] more research?

Comment author: Vladimir_Nesov 13 December 2009 09:44:30AM 1 point [-]

Relevant post: Readiness Heuristics

Comment author: wedrifid 13 December 2009 08:20:12AM 1 point [-]

Why can't they be confidence intervals around the probability after doing [some amount] more research?

That you can do.

Comment author: Jawaka 13 December 2009 11:30:39AM 0 points [-]

I feel the same way. I set the probabilities to 25 (not G alone) / 75 (G alone) after half an hour of reading, just because I wanted to have room to be more confident after 2 hours of reading.