Reading Yudkowsky, part 41

by Luke Muehlhauser on May 30, 2011 in Eliezer Yudkowsky,Resources,Reviews

AI researcher Eliezer Yudkowsky is something of an expert at human rationality, and at teaching it to others. His hundreds of posts at Less Wrong are a treasure trove for those who want to improve their own rationality. As such, I’m reading all of them, chronologically.

I suspect some of my readers want to “level up” their rationality, too. So I’m keeping a diary of my Yudkowsky reading. Feel free to follow along.

His 325th post is Zombies: The Movie is a short movie scene about philosophical zombies. Three Dialogues on Identity is three short stories about possible notions of “identity.”

Decoherence gets back to the quantum physics sequence which, like I said earlier, is way too hard for me to summarize, so I’ll just list the posts:

Many later posts depend on the quantum mechanics sequence of posts, but not in ways that require you to have read the whole thing. An example is The Dilemma: Science or Bayes?

Of course I had more than just one reason for spending all that time posting about quantum physics.  I like having lots of hidden motives, it’s the closest I can ethically get to being a supervillain.

But to give an example of a purpose I could only accomplish by discussing quantum physics…

In physics, you can get absolutely clear-cut issues.  Not in the sense that the issues are trivial to explain.  But if you try to apply Bayes to healthcare, or economics, you may not be able to formally lay out what is the simplest hypothesis, or what the evidence supports.  But when I say “macroscopic decoherence is simpler than collapse” it is actually strict simplicity; you could write the two hypotheses out as computer programs and count the lines of code. Nor is the evidence itself in dispute.

I wanted a very clear example - Bayes says “zig”, this is a zag – when it came time to break your allegiance to Science.

Now that’s an intriguing thought. A rationalist who breaks his allegiance to Science? What is Yudkowsky talking about?

“Oh, sure,” you say, “the physicists messed up the many-worlds thing, but give them a break, Eliezer!  No one ever claimed that the social process of science was perfect.  People are human; they make mistakes.”

But the physicists who refuse to adopt many-worlds aren’t disobeying the rules of Science.  They’re obeying the rules of Science.

What does Eliezer mean specifically?

The tradition handed down through the generations says that a new physics theory comes up with new experimental predictions that distinguish it from the old theory.  You perform the test, and the new theory is confirmed or falsified.  If it’s confirmed, you hold a huge celebration, call the newspapers, and hand out Nobel Prizes for everyone; any doddering old emeritus professors who refuse to convert are quietly humored.  If the theory is disconfirmed, the lead proponent publicly recants, and gains a reputation for honesty.

This is not how things do work in science; rather it is how things are supposed to work in Science.  It’s the ideal to which all good scientists aspire.

Now many-worlds comes along, and it doesn’t seem to make any new predictions relative to the old theory.  That’s suspicious.  And there’s all these other worlds, but you can’t see them.  That’s really suspicious.  It just doesn’t seem scientific.

So now put on your Science Goggles – you’ve still got them around somewhere, right?  Forget everything you know about Kolmogorov complexity, Solomonoff induction or Minimum Message Lengths.  That’s not part of the traditional training.  You just eyeball something to see how “simple” it looks.  The word “testable” doesn’t conjure up a mental image of Bayes’s Theorem governing probability flows; it conjures up a mental image of being in a lab, performing an experiment, and having the celebration (or public recantation) afterward.

Science-Goggles on:  The current quantum theory has passed all experimental tests so far.  Many-Worlds doesn’t make any new testable predictions – the amazing new phenomena it predicts are all hidden away where we can’t see them.  You can get along fine without supposing the other worlds, and that’s just what you should do.  The whole thing smacks of science fiction.  But it must be admitted that quantum physics is a very deep and very confusing issue, and who knows what discoveries might be in store?  Call me when Many-Worlds makes a testable prediction.

Science-Goggles off, Bayes-Goggles back on:

Bayes-Goggles on:  The simplest quantum equations that cover all known evidence don’t have a special exception for human-sized masses.  There isn’t even any reason to ask that particular question.  Next!

So Bayes is going to win everyone over, right? Wrong.

…if you say that Many-Worlds should replace the immensely successful Copenhagen Interpretation, adding on all these twin Earths that can’t be observed, just because it sounds more reasonable and elegant – not because it crushed the old theory with a superior experimental prediction – then you’re undoing the core scientific rule that prevents people from running out and putting angels into all the theories, because angels are more reasonable and elegant.

But anyway, here is the choice faced by the rationalist:

Are you really going to believe that large parts of the wavefunction disappear when you can no longer see them?  As a result of the only non-linear non-unitary non-differentiable non-CPT-symmetric acausal faster-than-light informally-specified phenomenon in all of physics?  Just because, by sheer historical contingency, the stupid version of the theory was proposed first?

Are you going to make a major modification to a scientific model, and believe in zillions of other worlds you can’t see, without a defining moment of experimental triumph over the old model?

Or are you going to reject probability theory?

Will you give your allegiance to Science, or to Bayes?

Wow. Okay, so where is this going?

I wanted to present you with a nice, sharp dilemma between rejecting the scientific method, or embracing insanity.

Why?  I’ll give you a hint:  It’s not just because I’m evil.  If you would guess my motives here, think beyond the first obvious answer.

Science Doesn’t Trust Your Rationality argues:

Science is built around the assumption that you’re too stupid and self-deceiving to just use Solomonoff induction.  After all, if it was that simple, we wouldn’t need a social process of science… right?

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{ 6 comments… read them below or add one }

Yair May 30, 2011 at 12:22 pm

The problem is that Science is being perfectly rational in judging theories not simply by their Kolmogorov complexity. There are several considerations here.

First, the arguments (that I know of) for this measure of complexity are noise-based arguments. But what are the parameters in which we have noise here? There really aren’t any plausible models that include noisy parameters such that the MWI would be simpler than the CI while still performing as well. The framework that argues for complexity doesn’t apply here. And even if it would apply, it would not necessarily be decisive; the simplicity, in mathematical complexity measurements, may not be so different.

Furthermore, Science in practice cares about predictability – the ability to predict experimental results. Complexity is a concern primarily because Computability is a concern. But computability isn’t complexity! In some cases it is more advantageous, computationally, to apply the CI or the HVI [Hidden Variables]. You can just solve some problems using these methods more easily that you can with methods based on MWI phrasings, just like certain math problems are easier in certain coordinates. Hence, it makes sense to keep an open mind and perhaps even an anti-Realist position; in practice, such an attitude will help you see which approach works best for the given problem.

Despite all of this, I’m very much attracted to the MWI. This is primarily because it is most elegant. It’s hard to explain the appeal of elegance, but it’s strong. The standard CI is utter rubbish, but I am equally attracted to a “process theology” like explanation, that sees Events as the bones of (single) Reality and quantum mechanics as indicating their statistical relations. I’m not sure if it can be formulated coherently, but I suspect it can. Finally, I’m repelled by Bohmian mechanics as introducing a whole layer to reality unnecessarily (it’s rather like introducing angels) – but also for simply being ugly. Again, I can’t explain the appeal of elegance. This essentially covers all interpretations – the rest are just variants thereof, in my (limited) understanding.


mpg May 30, 2011 at 1:18 pm

Wow, “Many Worlds, One Best Guess” is the best defence of MWI I have read.

Am I being irrational when I say that despite it’s elegant strength, I am still skeptical?


Gil S. May 30, 2011 at 8:27 pm

Eh… Does anyone actually read this? This is the 41th part >_< You seem to be interested in this, but I don't know, I just prefer the old CSA days. No offense.


soupsayer May 30, 2011 at 9:15 pm

Eh… Does anyone actually read this? This is the 41th part )_( You seem to be interested in this, but I don’t know, I just prefer the old CSA days. No offense.

It ain’t the old days anymore, Gil. It’s worthwhile to read EY, but mostly to learn about his distorted binary worldview and frightening ideology.

Luke has said that he doesn’t get paid for his posts to CSA, and since the world isn’t going to save itself from the fembots, he has diverted mosts of his efforts to doing so.


Taranu June 2, 2011 at 2:53 am

why is his worldview binary and his ideology frightening?


Tim Tyler June 6, 2011 at 1:10 pm

Yudkowsky plans to build a machine that he thinks will take over the world.


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