Rationality Quotes April 2014

elharo

Another month has passed and here is a new rationality quotes thread. The usual rules are:

Please post all quotes separately, so that they can be upvoted or downvoted separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself.
Do not quote from Less Wrong itself, HPMoR, Eliezer Yudkowsky, or Robin Hanson. If you'd like to revive an old quote from one of those sources, please do so here.
No more than 5 quotes per person per monthly thread, please.

And one new rule:

Provide sufficient information (URL, title, date, page number, etc.) to enable a reader to find the place where you read the quote, or its original source if available. Do not quote with only a name.

Another month has passed and here is a new rationality quotes thread. The usual rules are:

Please post all quotes separately, so that they can be upvoted or downvoted separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself.
Do not quote from Less Wrong itself, HPMoR, Eliezer Yudkowsky, or Robin Hanson. If you'd like to revive an old quote from one of those sources, please do so here.
No more than 5 quotes per person per monthly thread, please.

And one new rule:

Provide sufficient information (URL, title, date, page number, etc.) to enable a reader to find the place where you read the quote, or its original source if available. Do not quote with only a name.

It looks to me to be rather clear that what is being said ("myths are not evidence for Zeus") translates roughly to "myths are very weak evidence for Zeus, and so my beliefs are changed very little by them". Is there still a real misunderstanding here?

You are making a mistake in reasoning if you don't change your belief through that evidence. Your belief should change by orders of magnitude. A change from 10^{-18} to 10^{-15} is a strong change.

The central reason to believe that Zeus doesn't exist are weak priors.

Skeptics have ideas that someone has to prove something to them for them to believe it. In the Bayesian worldview you always have probabilities for your beliefs. Social obligations aren't part of it. "Good" evidence means that someone fulfilled a social obligation of providing a certain amount of proof. It doesn't refer to how strongly a Bayesian should update after being exposed to a piece of evidence.

There are very strong instincts for humans to either believe X is true or to believe X is false. It takes effort to think in terms of probabilities.

I agree with this comment, but I want to point out that there may be a problem with equating the natural language concept "strength of evidence" with the likelihood ratio.

You can compare two probabilities on either an additive or multiplicative scale. When applying a likelihood ratio of 1000, your prior changes by a multiplicative factor of 1000 (this actually applies to odds rather than probabilities, but for low probability events, the two approximate each other). However, on an additive scale, a change from 10^{-18} to 10^{-15} is really ... (read more)

0Murska12y

Yes, that is probably clear to most of us here. But, in reality, I and most likely also you discount probabilities that are very small, instead of calculating them out and changing our actions (we'll profess 'this is very unlikely' instead of 'this is not true', but what actually happens is the same thing). There's a huge amount of probability 10^{-18} deities out there, we just shrug and assume they don't exist unless enough strong (or 'good', I still don't see the difference there) evidence comes up to alter that probability enough so that it is in the realm of probabilities worth actually spending time and effort thinking about. This hypothetical skeptic, if pressed, would most likely concede that sure, it is /possible/ that Zeus exists. He'd even probably concede that it is more likely that Zeus exists than that a completely random other god with no myths about them exists. But he'd say that is fruitless nitpicking, because both of them are overwhelmingly unlikely to exist and the fact that they still might exist does not change our actions in any way. If you wish to argue this point, then that is fine, but if we agree here then there's no argument, just a conflict of language. I'm trying to say that where you would say "Probability for X is very low", most people who have not learned the terminology here would normally say "X is false", even if they would concede that "X is possible but very unlikely" if pressed on it.

2Richard_Kennaway12y

Where do those numbers come from?