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About Rationality Quotes
...so do these go to the main LW now, or do we keep them in Discussion?
My vote would be "to the main LW", but since I both want to discuss this and would like to play with the "feature" that allows moving a thread from one to the other at some point:
Discuss.
Why learning programming is a great idea even if you'd never want to code for a living
Personal decisions the leading cause of death
I've had this paper (pdf) in my "for LW" pile for a while, I didn't want to dump it in the open thread to have it promptly drowned out but neither could I think of much more to say to make it worth a top-level post on the main LW.
This paper analyzes the relationships between personal decisions and premature deaths in the United States. The analysis indicates that over one million of the 2.4 million deaths in 2000 can be attributed to personal decisions and could have been avoided if readily available alternative choices were made.
Conclusion: the impact that thinking better could have on people's lives is way underestimated.
Discuss. :)
Rationality quotes: September 2010
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.
- Please post all quotes separately, so that they can be voted up/down 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- Do not quote yourself.
- Do not quote comments/posts on LW/OB.
- No more than 5 quotes per person per monthly thread, please.
Book Club Update, Chapter 3 of Probability Theory
Previously: Book Club introductory post - Chapter 1 - Chapter 2
We will shortly move on to Chapter 3 (I have to post this today owing to vacation - see below). I have updated the previous post with a summary of chapter 2, with links to the discussion as appropriate. But first, a few announcements.
How to participate
This is both for people who have previously registered interest, as well as newcomers. This spreadsheet is our best attempt at coordinating 90+ Less Wrong readers interested in participating in "earnest study of the great literature in our area of interest".
If you are still participating, please let the group know - all you have to do is fill in the "Active (Chapter)" column. Write in an "X" if you are checked out, or the number of the chapter you are currently reading. This will let us measure attrition, as well as adapt the pace if necessary. If you would like to join, please add yourself to the spreadsheet. If you would like to participate in live chat about the material, please indicate your time zone and preferred meeting time. As always, your feedback on the process itself is more than welcome.
Refer to the Chapter 1 post for more details on how to participate and meeting schedules.
Facilitator wanted
I'm taking off on vacation today until the end of the month. I'd appreciate if someone wanted to step into the facilitator's shoes, as I will not be able to perform these duties in a timely manner for at least the next two weeks.
Chapter 3: Elementary Sampling Theory
Having derived the sum and product rules, Jaynes starts us in on a mainstay of probability theory, urn problems.
Readings for the week of 19/07: Sampling Without Replacement - Logic versus Propensity. Exercises: 3.1
Discussion starts here.
The red paperclip theory of status
Followup to: The Many Faces of Status (This post co-authored by Morendil and Kaj Sotala - see note at end of post.)
In brief: status is a measure of general purpose optimization power in complex social domains, mediated by "power conversions" or "status conversions".
What is status?
Kaj previously proposed a definition of status as "the ability to control (or influence) the group", but several people pointed out shortcomings in that. One can influence a group without having status, or have status without having influence. As a glaring counterexample, planting a bomb is definitely a way of influencing a group's behavior, but few would consider it to be a sign of status.
But the argument of status as optimization power can be made to work with a couple of additional assumptions. By "optimization power", recall that we mean "the ability to steer the future in a preferred direction". In general, we recognize optimization power after the fact by looking at outcomes. Improbable outcomes that rank high in an agent's preferences attest to that agent's power. For the purposes of this post, we can in fact use "status" and "power" interchangeably.
In the most general sense, status is the general purpose ability to influence a group. An analogy to intelligence is useful here. A chess computer is very skilled at the domain of chess, but has no skill in any other domain. Intuitively, we feel like a chess computer is not intelligent, because it has no cross-domain intelligence. Likewise, while planting bombs is a very effective way of causing certain kinds of behavior in groups, intuitively it doesn't feel like status because it can only be effectively applied to a very narrow set of goals. In contrast, someone with high status in a social group can push the group towards a variety of different goals. We call a certain type of general purpose optimization power "intelligence", and another type of general purpose optimization power "status". Yet the ability to make excellent chess moves is still a form of intelligence, but only a very narrow one.
Book Club Update, Chapter 2 of Probability Theory
Previously: Book Club introductory post - First update and Chapter 1 summary
Discussion on chapter 1 has wound down, we move on to Chapter 2 (I have updated the previous post with a summary of chapter 1 with links to the discussion as appropriate). But first, a few announcements.
How to participate
This is both for people who have previously registered interest, as well as newcomers. This spreadsheet is our best attempt at coordinating 80+ Less Wrong readers interested in participating in "earnest study of the great literature in our area of interest".
If you are still participating, please let the group know - all you have to do is fill in the "Active (Chapter)" column. Write in an "X" if you are checked out, or the number of the chapter you are currently reading. This will let us measure attrition, as well as adapt the pace if necessary. If you would like to join, please add yourself to the spreadsheet. If you would like to participate in live chat about the material, please indicate your time zone and preferred meeting time. As always, your feedback on the process itself is more than welcome.
Refer to the previous post for more details on how to participate and meeting schedules.
Chapter 2: The Quantitative Rules
In this chapter Jaynes carefully introduces and justifies the elementary laws of plausibility, from which all later results are derived.
(Disclosure: I wasn't able to follow all the math in this chapter but I didn't let it deter me; the applications in later chapters are more accessible. We'll take things slow, and draw on such expertise as has been offered by more advanced members of the group. At worst this chapter can be enjoyed on a purely literary basis.)
Sections: The Product Rule - The Sum Rule. Exercises: 2.1 and 2.2
Chapter 2 works out the consequences of the qualitative desiderata introduced at the end of Chapter 1.
The first step is to consider the evaluation of the plausibility (AB|C), from the possibly relevant inputs: (B|C), (A|C), (A|BC) and (B|AC). Considerations of symmetry and the desideratum of consistency lead to a functional equation known as the "associativity equation": F(F(x,z),z)=F(x,F(y,z)), characterizing the the function F such that (AB|C)=F[(B|C),(A|BC)]. The derivation that follows requires some calculus, and shows by differentiating then integrating back the form of the product rule:
w(AB|C)=w(A|BC)w(B|C)=w(B|AC)w(A|C)
Having obtained this, the next step is to establish how (A|B) is related to (not-A|B). The functional equation in this case is
x*S(S(y)/x)=y*S(S(x)/y)
and the derivation, after some more calculus, leads to S(x)=(1-x^m)^(1/m). But the value of m is irrelevant, and so we end up with the two following rules:
p(AB|C)=p(A|BC)p(B|C)=p(B|AC)p(A|C)
p(not-A|B)+p(A|B)=1
The exercises provide a first opportunity to explore how these two rules yield a great many other ways of assessing probabilities of more complex propositions, for instance p(C|A+B), based on the elementary probabilities.
Sections: Qualitative Properties - Numerical Values - Notation and Finite Sets Policy - Comments. Exercises: 2.3
Jaynes next turns back to the relation between "plausible reasoning" and deductive logic, showing the latter as a limiting case of the former. The weaker syllogisms shown in Chapter 1 correspond to inequalities that can be derived from the product rule, and the direction of these inequalities start to point to likelihood ratios.
The product and sum rules allow us to consider the particular case when we have a finite set of mutually exclusive and exhaustive propositions, and background information which is symmetrical about each such proposition: it says the same about any one of them that it says about any other. Considering two such situations, where the propositions are the same but the labels we give them are different, Jaynes shows that, given our starting desiderata, we cannot do other than to assign the same probabilities to propositions which we are unable to distinguish otherwise than by their labels.
This is the principle of indifference; its significance is that even though what we have derived so far is an infinity of functions p(x) generated by the parameter m, the desiderata entirely "pin down" the numerical values in this particular situation.
So far in this chapter we had been using p(x) as a function relating the plausibilities of propositions, such that p(x) was an arbitrary monotonic function of the plausibility x. At this point Jaynes suggests that we "turn this around" and say that x is a function of p. These values of p, probabilities, become the primary mathematical objects, while the plausibilities "have faded entirely out of the picture. We will just have no further use for them".
The principle of indifference now allows us to start computing numerical values for "urn probabilities", which will be the main topic of the next chapter.
Exercise 2.3 is notable for providing a formal treatment of the conjunction fallacy.
Chapter 2 ends with a cautionary note on the topic of justifying results on infinite sets only based on a "well-behaved" process of passing to the limit of a series of finite cases. The Comments section addresses the "subjective" vs "objective" distinction.
Book Club Update and Chapter 1
This post summarizes response to the Less Wrong Book Club and Study Group proposal, floats a tentative virtual meetup schedule, and offers some mechanisms for keeping up to date with the group's work. We end with summaries of Chapter 1.
Statistics
The proposal for a LW book club and study group, initially focusing on E.T. Jaynes' Probability Theory: The Logic of Science (a.k.a. PT:TLOS), drew an impressive response with 57 declarations of intent to participate. (I may have missed some or misinterpreted as intending to participate some who were merely interested. This spreadsheet contains participant data and can be edited by anyone (under revision control). Please feel free to add, remove or change your information.) The group has people from no less than 11 different countries, in time zones ranging from GMT-7 to GMT+10.
Live discussion schedule and venues
Many participants have expressed an interest in having informal or chatty discussions over a less permanent medium than LW itself, which should probably be reserved for more careful observations. The schedule below is offered as a basis for further negotiation. You can edit the spreadsheet linked above with your preferred times, and by the next iteration if a different clustering emerges I will report on that.
- Tuesdays at UTC 18:00 (that is 1pm Bay Area, 8pm in Europe, etc. - see linked schedule for more)
- Wednesdays at UTC 11:00 (seems preferred by Australian participants)
- Sundays at UTC 18:00 (some have requested a weekend meeting)
The unofficial Less Wrong IRC channel is the preferred venue. An experimental Google Wave has also been started which may be a useful adjunct, in particular as we come to need mathematical notations in our discussions.
I recommend reading the suggested material before attending live discussion sessions.
Less Wrong Book Club and Study Group
Do you want to become stronger in the way of Bayes? This post is intended for people whose understanding of Bayesian probability theory is currently somewhat tentative (between levels 0 and 1 to use a previous post's terms), and who are interested in developing deeper knowledge through deliberate practice.
Our intention is to form an online self-study group composed of peers, working with the assistance of a facilitator - but not necessarily of a teacher or of an expert in the topic. Some students may be somewhat more advanced along the path, and able to offer assistance to others.
Our first text will be E.T. Jaynes' Probability Theory: The Logic of Science, which can be found in PDF form (in a slightly less polished version than the book edition) here or here.
We will work through the text in sections, at a pace allowing thorough understanding: expect one new section every week, maybe every other week. A brief summary of the currently discussed section will be published as an update to this post, and simultaneously a comment will open the discussion with a few questions, or the statement of an exercise. Please use ROT13 whenever appropriate in your replies.
A first comment below collects intentions to participate. Please reply to this comment only if you are genuinely interested in gaining a better understanding of Bayesian probability and willing to commit to spend a few hours per week reading through the section assigned or doing the exercises.
Rationality quotes: June 2010
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.
- Please post all quotes separately, so that they can be voted up/down 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 comments/posts on LW/OB.
- No more than 5 quotes per person per monthly thread, please.
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