trentmkelly/LessWrong-43k huggingface dataset:
Proof Length and Logical Counterfactuals Revisited
by orthonormal — 2016-02-10T18:56:38.000Z

Update: This version of the Trolljecture fails too; see the counterexample due to Sam.

In An Informal Conjecture on Proof Length and Logical Counterfactuals, Scott discussed a "trolljecture" from a MIRI workshop, which attempted to justify (some) logical counterfactuals based on the lengths of proofs of various implications. Then Sam produced a counterexample, and Benja pointed to another counterexample.

But at the most recent MIRI workshop, I talked with Jonathan Lee and Holger Dell about a related way of evaluating logical counterfactuals, and we came away with a revived trolljecture!

Let's say we have a recursively enumerable set of axioms S (in the language of PA) and a statement φ. Then we define the "distance" dS(φ) as the length of the shortest proof of φ using the axioms S. (We set dS(φ)=∞ if there is no such proof.)

And now we define a valuation νS(φ)=dS(¬φ)dS(¬φ)+dS(φ) which we will interpret as the "probability" of the logical counterfactual that S implies φ. (This is undefined when φ is undecidable given S; we could define it as a limit when searching over proofs of bounded length, in which case it would equal 0.5 in such cases. But as we shall see, this is not the case we care about.)

This valuation has the trivial properties that νS(φ)=1 if S⊢φ and S⊬¬φ, and similarly νS(φ)=0 if S⊬φ and S⊢¬φ. But what's more interesting are the properties that this valuation has if S is inconsistent.

If there is a short proof of φ from S, and a much longer proof of ¬φ from S, then νS(φ)≈1. Moreover, we have an approximate coherence condition νS(φ∧ψ)+νS(φ∧¬ψ)≈νS(φ) so long as either φ or ψ has a proof from S that is much shorter than the proof of ⊥ from S. (See the notes below.)

And this gets some key examples "correct" if we add the axioms that we actually care about (and which make the problem truly counterfactual). For instance, let's take Sam's counterexample to the original Trolljecture:

def U():
if A() = 1:
if PA is consistent:
return 10
else:
return 0
else: return 5

def A():
if PA ⊢ A() = 1 → U() = 10:
return 1
else: return 2

In that case, A() actually returns 2 and U() returns 5, but PA proves the "incorrect" counterfactual that A()=1→U()=0 and does not prove the "correct" counterfactual that A()=1→U()=10. (Read the linked post if this puzzles you.)

But what if we consider reasoning from the inconsistent premises that PA is c

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The Brain Preservation Foundation's Small Mammalian Brain Prize won
by gwern — 2016-02-09T21:02:02.585Z

The Brain Preservation Foundation’s Small Mammalian Brain Prize has been won with fantastic preservation of a whole rabbit brain using a new fixative+slow-vitrification process.

BPF announcement (21CM’s announcement)

evaluation

The process was published as “Aldehyde-stabilized cryopreservation”, McIntyre & Fahy 2015 (mirror)

We describe here a new cryobiological and neurobiological technique, aldehyde-stabilized cryopreservation (ASC), which demonstrates the relevance and utility of advanced cryopreservation science for the neurobiological research community. ASC is a new brain-banking technique designed to facilitate neuroanatomic research such as connectomics research, and has the unique ability to combine stable long term ice-free sample storage with excellent anatomical resolution. To demonstrate the feasibility of ASC, we perfuse-fixed rabbit and pig brains with a glutaraldehyde-based fixative, then slowly perfused increasing concentrations of ethylene glycol over several hours in a manner similar to techniques used for whole organ cryopreservation. Once 65% w/v ethylene glycol was reached, we vitrified brains at −135 °C for indefinite long-term storage. Vitrified brains were rewarmed and the cryoprotectant removed either by perfusion or gradual diffusion from brain slices. We evaluated ASC-processed brains by electron microscopy of multiple regions across the whole brain and by Focused Ion Beam Milling and Scanning Electron Microscopy (FIB-SEM) imaging of selected brain volumes. Preservation was uniformly excellent: processes were easily traceable and synapses were crisp in both species. Aldehyde-stabilized cryopreservation has many advantages over other brain-banking techniques: chemicals are delivered via perfusion, which enables easy scaling to brains of any size; vitrification ensures that the ultrastructure of the brain will not degrade even over very long storage times; and the cryoprotectant can be removed, yielding a perfusable aldehyde-preserved brain which is suitable for a wide variety of brain assays…We have shown that both rabbit brains (10 g) and pig brains (80 g) can be preserved equally well. We do not anticipate that there will be significant barriers to preserving even larger brains such as bovine, canine, or primate brains using ASC.

(They had problems with 2 pigs and got 1 pig brain s

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Religious and Rational?
by Gleb_Tsipursky — 2016-02-09T20:12:28.609Z

Reverend Caleb Pitkin, an aspiring rationalist and United Methodist Minister, wrote an article about combining religion and rationality which was recently published on the Intentional Insights blog. He's the only Minister I know who is also an aspiring rationalist, so I thought it would be an interesting piece for Less Wrong as well. Besides, it prompted an interesting discussion on the Less Wrong Facebook group, so I thought some people here who don't look at the Facebook group might be interested in checking it out as well. Caleb does not have enough karma to post, so I am posting it on his behalf, but he will engage with the comments.

______________________________________________________________________________

Religious and Rational?

“Wisdom shouts in the street; in the public square she raises her voice.”

Proverbs 1:20 Common English Bible

The Biblical book of Proverbs is full of imagery of wisdom personified as a woman calling and extorting people to come to her and listen. The wisdom contained in Proverbs is not just spiritual wisdom but also contains a large amount of practical wisdom and advice. What might the wisdom of Proverbs and rationality have in common? The wisdom literature in scripture was meant to help people make better and more effective decisions. In today’s complex and rapidly changing world we have the same need for tools and resources to help us make good decisions. One great source of wisdom is methods of better thinking that are informed by science.

Now, not everyone would agree with comparing the wisdom of Proverbs with scientific insights. Doing so may not sit well with some in the secular rationality community who view all religion as inherently irrational and hindering clear thinking. It also might not sit well with some in my own religious community who are suspicious of scientific thinking as undermining traditional faith. While it would take a much longer piece to try to completely defend either religion or secular rationality I’m going to try and demonstrate some ways that rationality is useful for a religious person.

The first way that rationality can be useful for a religious person is in the living of our daily lives. We are faced with tasks and decisions each day that we try to do our best in. L...
Meetup : Quantum Homeschooling
by JoshuaFox — 2016-02-09T09:30:00.824Z

Discussion article for the meetup : Quantum Homeschooling

WHEN:
16 February 2016 07:00:00PM (+0200)

WHERE:
Google Campus, Yigal Alon 98, 34th floor, Tel Aviv

This time we have two talks:

Louise Fox will talk about homeschooling in Israel.

Zvi Schreiber will talk about interpretations of quantum mechanics.

It will be at Google Campus, 34th floor, and not the Google lecture hall where we have been meeting until recently.

You can call Joshua at 0545691165 if you have a hard time finding us.

Please RSVP at the Facebook Event
https://www.facebook.com/events/1560682680921315/

Discussion article for the meetup : Quantum Homeschooling
Is Spirituality Irrational?
by lisper — 2016-02-09T01:42:33.894Z

[Originally published at Intentional Insights in response to Religious and Rational]

Spirituality and rationality seem completely opposed. But are they really?

To get at this question, let's start with a little thought experiment. Consider the following two questions:

1. If you were given a choice between reading a physical book (or an e-book) or listening to an audiobook, which would you prefer?

2. If you were given a choice between listening to music, or looking at the grooves of a phonograph record through a microscope, which would you prefer?

But I am more interested in the answer to a third question:

3. For which of the first two questions do you have a stronger preference between the two options?

Most people will have a stronger preference in the second case than the first. But why? Both situations are in some sense the same: there is information being fed into your brain, in one case through your ears and in the other through your eyes. So why should people's preference for ears be so much stronger in the case of music than books?

There is something in the essence of music that is lost in the translation between an audio and a visual rendering. The same loss happens for words too, but to a much lesser extent. Subtle shades of emphasis and tone of voice can convey essential information in spoken language. This is one of the reasons that email is so notorious for amplifying misunderstandings. But the loss in much greater in the case of music.

The same is true for other senses. Color is one example. A blind person can abstractly understand what light is, and that color is a byproduct of the wavelength of light, and that light is a form of electromagnetic radiation... yet there is no way for a blind person to experience subjectively the difference between red and blue and green. But just because some people can't see colors doesn't mean that colors aren't real.

The same is true for spiritual experiences.

Now, before I expand that thought, I want to give you my bona fides. I am a committed rationalist, and an atheist (though I don't like to self-identify as an atheist because I'd rather focus on what I *do* believe in rather than what I don't). So I am not trying to convince you th...
Naturalistic Logical Updates
by abramdemski — 2016-02-09T01:28:34.000Z

Vadim pointed out in a comment to my post on logical counterfactuals that a very similar idea had been explained in a LessWrong post summarizing work by Vladimir Slepnev and Paul Christiano at a MIRI workshop in 2013. The algorithm which they suggested was called UDT 1.5. In fact, the essential idea is already argued by Vladimir Slepnev (cousin_it) in a post from 2012: Should logical probabilities be updateless too?.

Here, I continue to develop these ideas and those in my logical dutch-book post. I present an alternate prior to the one which was used for UDT 1.5. I show that this new prior has naturalistic logical updates, a kind of improvement-endorsing property which seems likely to work well with UDT. This property also gets around Paul Christiano's paradox of ignorance.

Motivation

Slepnev motivates the problem with a variant of counterfactual mugging, inspired by a post by Wei Dai but simplified:

Suppose Omega (the near-omniscient near-omnipotent and almost perfectly trustworthy agent who prefers the pronouns ve/ver) appears before you. Omega tells you that ve has computed the millionth binary digit of π, and that before knowing what the digit was, ve had committed to the following procedure: if the millionth digit is zero, ask you for $100. If the millionth digit is one, give you $10,000 only if you would have given Omega the $100 had the digit been zero; otherwise, give you nothing. Omega then tells you that the millionth digit was in fact zero, and asks you for $100.

Suppose you already use a variant of UDT, so you take the actions you would have approved of ahead of time. If you are a "smart" agent who already knew the millionth digit of π and only calculated expected utility of universes consistent with this knowledge, you'd turn Omega down. If you're a "dumb" agent who doesn't, you'd give Omega the $100. (This is true even though UDT uses a kind of logical counterfactual; a UDT agent takes a counterfactual on its possible actions, not anything else, so it still doesn't consider the worlds where digits of π are different.)

This means that "dumb" agents don't want to become "smart" agents. A UDT-like agent which improves its beliefs over time by proving more theorems will be temporally inconsistent. This calls into question approaches to logical uncertainty which rely on estimates which improve given more time, such as uniform coherence.

My intuition is

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Require contributions in advance
by Viliam — 2016-02-08T12:55:58.720Z

If you are a person who finds it difficult to tell "no" to their friends, this one weird trick may save you a lot of time!

Scenario 1

Alice: "Hi Bob! You are a programmer, right?"

Bob: "Hi Alice! Yes, I am."

Alice: "I have this cool idea, but I need someone to help me. I am not good with computers, and I need someone smart whom I could trust, so they wouldn't steal my idea. Would you have a moment to listen to me?"

Alice explains to Bob her idea that would completely change the world. Well, at the least the world of bicycle shopping.

Instead of having many shops for bicycles, there could be one huge e-shop that would collect all the information about bicycles from all the existing shops. The customers would specify what kind of a bike they want (and where they live), and the system would find all bikes that fit the specification, and display them ordered by lowest price, including the price of delivery; then it would redirect them to the specific page of the specific vendor. Customers would love to use this one website, instead of having to visit multiple shops and compare. And the vendors would have to use this shop, because that's where the customers would be. Taking a fraction of a percent from the sales could make Alice (and also Bob, if he helps her) incredibly rich.

Bob is skeptical about it. The project suffers from the obvious chicken-and-egg problem: without vendors already there, the customers will not come (and if they come by accident, they will quickly leave, never to return again); and without customers already there, there is no reason for the vendors to cooperate. There are a few ways how to approach this problem, but the fact that Alice didn't even think about it is a red flag. She also has no idea who are the big players in the world of bicycle selling; and generally she didn't do her homework. But after pointing out all these objections, Alice still remains super enthusiastic about the project. She promises she will take care about everything -- she just cannot write code, and she needs Bob's help for this part.

Bob believes strongly in the division of labor, and that friends should help each other. He considers Alice his friend, and he will likely need some help from her in the future. Fact is, with perfect specification, he could make the webpage in a week or two. But he considers bicycles to be an extremely boring topic, so he wants to sp...
Altruistic parenting
by  — 2016-02-08T11:57:16.935Z

I just read this article about the felicific calculus of parenthood.

The average happiness worldwide is 5.1 on a one out of ten scale; Americans are at 7.1. Arbitrarily deciding that one year of a 10 life is equivalent to two years of a 5 life, the cost per QALY of having a child for total utilitarians is $5500.

However, NICE’s threshold for cost effectiveness of a health intervention is about $30,000 (20,000 pounds) per QALY. Therefore, for total utilitarians, having a child may be considered a cost-effective intervention, although not an optimal intervention.

...surrogacy is an underexplored way to do good. Rather than costing money, the first-time surrogate earns thirty thousand dollars, which can grow to forty thousand dollars for experienced surrogates– and it still creates 109 QALYs that otherwise would not exist. These children are likely to grow up in wealthy families who really, really want to have them, and are thus likely to be even happier than this analysis suggests.

In the comments section, the following grabbed my attention.

Estimates for the size of a sustainable human population appear to mostly range between 2 billion and 10 billion, and the meta-analysis here (http://bioscience.oxfordjournals.org/content/54/3/195) suggests that the best point estimate is around 7.7 billion. Meanwhile most estimates of population growth over the next hundred years suggest the total population will reach 10-11 billion. It seems likely that at some point in the next couple hundred years, the population will decrease substantially due to a Malthusian catastrophe. This transition is likely to cause a great deal of suffering. Surely even a total utilitarian would agree that it would be better for the necessary drop in population to be as small as possible.

And even if the population never rises above sustainable carrying capacity, it’s not obvious that total utilitarians should see a larger population as preferable. The drop in happiness due to increased competition for resources could outweigh the benefit of an additional person existing and having experiences.

Then, I read this article. Here are the highlights:

Bryan Caplan’s excellent book Selfish Reasons to Have More Kids[7] reviews the evidence from 40 years of adoption and twin studies with a frank

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Lesswrong Survey - invitation for suggestions
by Elo — 2016-02-08T08:07:23.753Z

Given that it's been a while since the last survey (http://lesswrong.com/lw/lhg/2014_survey_results/)

It's now time to open the floor to suggestions of improvements to the last survey. If you have a question you think should be on the survey (perhaps with reasons why, predictions as to the result, or other useful commentary about a survey question)

Alternatively questions that should not be included in the next survey, with similar reasons as to why...

survey is now up (2016-03-26) http://lesswrong.com/lw/nfk/lesswrong_2016_survey/
Open Thread, Feb 8 - Feb 15, 2016
by Elo — 2016-02-08T04:47:02.516Z

If it's worth saying, but not worth its own post (even in Discussion), then it goes here.

Notes for future OT posters:

1. Please add the 'open_thread' tag.

2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)

3. Open Threads should be posted in Discussion, and not Main.

4. Open Threads should start on Monday, and end on Sunday.
Thoughts on Logical Dutch Book Arguments
by abramdemski — 2016-02-07T23:10:22.000Z

This post examines the application of Dutch Book arguments to logical uncertainty, as part of an attempt to fill out the ideas I speculated on in this post.

An important question we're currently facing is how to relate logical uncertainty to logical priors.

By logical prior, I mean an assignment of real numbers representing degree of belief to sentences, P(ϕ). This assignment is usually required to be coherent; I'll briefly review what Dutch Book arguments have to say about this before dealing with logical uncertainty.

By logical uncertainty, I mean the problem of making predictions under time constraints, so that we are unable to use all of our relevant knowledge. We can formalize this as the problem of designing a quickly computable probability function p(x) predicting a more slowly computable f(x). I have in mind things like Scott's three levels of difficulty.

This division between the problem of logical priors and logical uncertainty has been implicit in Scott and I's work for a while now, but we initially didn't make a full distinction between them. These really are different problems. We want the two to be connected, but that's an open problem for now.

The most obvious way for them to be connected would be for Pt to have the kinds of good properties which are discussed in connection with logical uncertainty. (Level 3 of Scott's hierarchy is especially interesting in this respect.) However, in this post I'll take a different route, and discuss what kinds of Dutch book arguments we might apply to Pt.

Doubting Coherence

I won't review the whole of the classic Dutch Book argument, but it is detailed here. The conclusion is this. A function P(ϕ) expressing degrees of belief for an agent must satisfy three conditions:

0≤P(ϕ)≤1

If ϕ is a tautology, then P(ϕ)=1.

(Additivity) If ϕ and ψ are mutually exclusive, then P(ϕ∨ψ)=P(ϕ)+P(ψ).

The argument proceeds by showing that if any of the constraints are violated, then a bookie can put together a set of bets which the agent will be willing to buy or sell, such that the bookie is guaranteed to profit on the whole no matter what the outcome of the bets may be. This set of bets is the "Dutch Book".

One might assume that this argument can be employed to justify coherence for logical priors. However, this isn't clear. The paper From Classical to Intuitionistic Probability points out that Dutch Book arguments assume every b

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Conveying rational thinking about long-term goals to youth and young adults
by Gleb_Tsipursky — 2016-02-07T01:54:30.519Z

More than a year ago, I discussed here how we at Intentional Insights intended to convey rationality to young adults through our collaboration with the Secular Student Alliance. This international organization unites over 270 clubs at colleges and high schools in English-speaking countries, mainly the US, with its clubs spanning from a few students to a few hundred students. The SSA's Executive Director is an aspiring rationalist and CFAR alum who is on our Advisory Board.

Well, we've been working on a project with the SSA for the last 8 months to create and evaluate an event aimed to help its student members figure out and orient toward the long term, thus both fighting Moloch on a societal level and helping them become more individually rational as well (the long-term perspective is couched in the language of finding purpose using science) It's finally done, and here is the link to the event packet. The SSA will be distributing this packet broadly, but in the meantime, if you have any connections to secular student groups, consider encouraging them to hold this event. The event would also fit well for adult secular groups with minor editing, in case any of you are involved with them. It's also easy to strip the secular language from the packet, and just have it as an event for a philosophy/science club of any sort, at any level from youth to adult. Although I would prefer you cite Intentional Insights when you do it, I'm comfortable with you not doing so if circumstances don't permit it for some reason.

We're also working on similar projects with the SSA, focusing on being rational in the area of giving, so promoting Effective Altruism. I'll post it here when it's ready.
Meetup : Less Wrong NH Meetup
by Tuk — 2016-02-06T23:16:02.065Z

Discussion article for the meetup : Less Wrong NH Meetup

WHEN:
09 February 2016 07:00:00PM (-0500)

WHERE:
269 Pearl St, Manchester NH 03104

The twelfth NH meet-up is Tuesday, 2/9, in Manchester, NH at 7 pm at a private residence. Light refreshments will be provided.

Have you read Rationality: from AI to Zombies, or any of the Sequences on Less Wrong? Maybe you're just a fan of Harry Potter and the Methods of Rationality. Come hang out with us and discuss optimization of whatever it is you want to optimize.

Agenda: Instrumental techniques

You may want to bring a notebook.

https://www.facebook.com/events/204242433261978/

https://www.facebook.com/groups/695201067251306/

Discussion article for the meetup : Less Wrong NH Meetup