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RobinHanson comments on Reductionism - Less Wrong

40 Post author: Eliezer_Yudkowsky 16 March 2008 06:26AM

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Comment author: RobinHanson 16 March 2008 11:23:24AM 4 points [-]

This is a situation where a lot of confidence seems appropriate, though of course not infinite confidence. I'd put the chance that Eliezer is wrong here at below one percent.

Comment author: Perplexed 30 July 2010 04:47:33AM 5 points [-]

I really have no idea what Eliezer being wrong on this would mean. Is the subject matter of this posting the nature of the territory or is it advice on the best way to construct maps?

What conceivable observations might cause you to revise that 1% probability estimate up to, say, 80%?

As I see it, reductionism is not a hypothesis about the world; it is a good heuristic to direct research.

Comment author: ata 30 July 2010 05:07:35AM 5 points [-]

I take the main thesis as being summed up by this sentence around the end:

Reductionism is not a positive belief, but rather, a disbelief that the higher levels of simplified multilevel models are out there in the territory.

Specific non-reductionist hypotheses, in the extremely unlikely event that any are supported by evidence, could cast doubt on reductionism. We'd need to find a specific set of circumstances under which reality appears to be computing the same entities at multiple levels simultaneously and applying different laws at each level, or we'd need to find fundamental laws that talk about non-fundamental objects. For example, if the Navy gunner were actually correct that you need to use Newtonian mechanics instead of relativity in order to get the right answer when computing artillery trajectories (given the further unlikely assumption that we couldn't find a simpler explanation for this state of affairs than "physical reductionism as a whole is wrong").

Comment author: Perplexed 30 July 2010 05:54:14AM 0 points [-]

Ok, let me try to construct an example of a non-reductionist hypothesis. Eliezer says that it would be a claim that higher levels of simplified multilevel models are out there in the territory. So, as a multi-level model, let us take (low-level) QCD+electroweak, (mid-level): nucleons, mesons, electrons, neutrinos, photons; (high-level): atomic theory with 92 kinds of atoms + photons.

Now as I understand it, reductionism forbids me to believe that photons and electrons - entities which exist in higher level models - are actually out there in the territory. What am I doing wrong here? Could you maybe give me an example of a hypothesis which a reductionist ought to disbelieve?

Comment author: ata 30 July 2010 06:38:50AM 0 points [-]

As I understand it, photons and electrons are identified as elementary particles in the Standard Model. Wouldn't that be considered the lowest level?

Comment author: Perplexed 31 July 2010 02:50:53AM 0 points [-]

Sure, they exist in both the lowest (so far) level and in the next level up. But Eliezer wants to forbid things at "higher levels of simplified multilevel models" from existing out there in the territory. If that doesn't include electrons in this example, then I don't know what it includes. I don't understand exactly what it is that is forbidden. Is it type errors - confusing map entities with territory entities? Is it failing to yet be convinced by what someone else thinks is the best low-level model? Is it somehow imagining that, say, atoms still exist in the territory while simultaneously imagining that atoms are made of more fundamental things which also exist in the territory? I seems to me that the definition of reductionism that Eliezer has given is completely useless because no one sane would proclaim themselves as non-reductionists. He is attacking a straw-man position, as far as I can see.

Comment author: taryneast 16 December 2010 07:48:45AM 8 points [-]

AFAICS, he is not "forbidding" a plane's wing from existing at the level of quark. He's just saying that "plane's wing" is a label that we are giving to "that bunch of quarks arranged just so over there". This as opposed to "that other bunch of quarks arranged just so over there" that we call "a human".

That the arrangement of a set of quarks does not have a fundamental "label" at the most basic level. The classification of the first bunch o' quarks (as separate from the second) is something that we do on a "higher level" than the quarks themselves.

Comment author: bigjeff5 01 February 2011 09:06:37PM *  1 point [-]

But Eliezer wants to forbid things at "higher levels of simplified multilevel models" from existing out there in the territory.

You're confusing the map and the territory.

The territory is only quarks (or whatever quarks may be made of). There is nothing else, it's just a big mass of quarks.

The map is the description of this bunch of quarks is human, while that bunch is an airplane.

There was a time when physicists thought that earth, air, water, and fire were the reality - that they were fundamental. Then they discovered molecules, and they thought those were fundamental. Then they discovered atoms, and thought those were fundamental. Etc. on down until the current (I think, I'm not a physicist) belief that quarks are fundamental.

At no point did reality change. Reality did not change when we discovered rocks were made up of molecules - the map was simply inaccurate. The reality was that rocks were always made up of molecules. The same when we discovered that molecules were made of atoms. It was always true, our map was simply not as accurate as we thought it was.

You could quite accurately say the map is wrong because it does not perfectly reflect reality, but the map is extremely useful, so we should not discard it. We should simply recognize that it is a map, it is not the territory. It's a representation of reality, it is not what is real. We know Newtonian Mechanics is a less accurate map than Special Relativity, but it is more useful than SR in many cases because it doesn't have the detail cluttering up the map that SR has. Yeah, it's less precise, but for calculating the trajectory of an artillery shell it is more than good enough.

The different levels are maps, there is only one territory.

Comment author: DanielLC 29 March 2011 06:08:58AM *  2 points [-]

The territory is only quarks (or whatever quarks may be made of).

It's also leptons.

Comment author: Sniffnoy 02 February 2011 02:01:42AM *  1 point [-]

In short, you seem to be confusing {A} with A.

Comment author: Perplexed 02 February 2011 02:10:47AM 0 points [-]

Too short. But intriguing. Please explain.

Comment author: Sniffnoy 03 February 2011 06:24:31AM *  1 point [-]

What I mean is, your objection doesn't hold water because raw objects at lower levels can always be put in a wrapper to be made suitable for use at a higher level. E.g. if we consider an elementary particles level, and a general-particles-which-for-now-we-will-consider-as-sets-of-particles-level (yes, I realize this almost certainly does not actually work in actual physics), then in the higher level we have proton={up_1, up_2, down}, and electron_H={electron_L}. But for most purposes the distinction between electron and {electron} is irrelevant, so we elide it. Your point seems to me analogous to the statement "But 2 can't be the rational number {...,(-4,-2),(2,1),(-2,-1),(4,2),...}, it's the integer {...(1,-1),(2,0),(3,1),...}!"

Comment author: Perplexed 03 February 2011 12:45:31PM 3 points [-]

Ah! Good point. And now that it is explained, good analogy.

I still have some reservations about Eliezer's approach to reductionism/anti-holism and his equation of the idea of "emergence" with some kind of mystical mumbo-jumbo. But this is a complicated subject and philosophers of science much more careful than myself have addressed it better than I can.

Thank you, though, for pointing out that my argument in this thread can be refuted so easily simply by taking Eliezer a little less literally. Electrons at one level reduce to electrons at a lower level. But the two uses of the word 'electron' in the above sentence refer to different (though closely related) entities. As closely related as A and {A}. You are right. Cool.

Comment author: timtyler 15 August 2010 07:10:36PM *  0 points [-]

"Reductionism" has come to have two meanings:

"Reductionism can either mean (a) an approach to understanding the nature of complex things by reducing them to the interactions of their parts, or to simpler or more fundamental things or (b) a philosophical position that a complex system is nothing but the sum of its parts, and that an account of it can be reduced to accounts of individual constituents."

This post is about the second meaning. But that meaning is silly, useless, and redundantly duplicates other terms for such nonsense - such as reducibility and irreducibility.

We should kill off that meaning - and reclaim the meaning of the term that is useful and sensible. Posts like this one - which use the second meaning - are part of the problem.

Comment author: simplicio 15 August 2010 07:24:32PM 0 points [-]

Why is it silly to say that higher level phenomena reduce, in principle, to ontologically fundamental particle fields?

Comment author: timtyler 15 August 2010 07:30:58PM *  0 points [-]

This discusssion is about the term "reductionism" - which is obviously some kind of philosophy about "reducing" things - but the cited definitions differ on the details of exactly what the term means.

The first meaning just states the obvious, IMO. Also, other terms have that kind of nonsense covered. There is no need to overload the perfectly useful and good term "reductionism" with something that is only useful for the refutation of nonsense. It just causes the type of mix-up that you see in this thread.

Comment author: simplicio 15 August 2010 07:33:54PM 0 points [-]

I understand, I just don't get why you object to reductionism as exemplified by the second definition. It seems to me a fairly reasonable philosophical position.

Comment author: timtyler 15 August 2010 07:42:02PM *  0 points [-]

I object to that terminology because it overloads a useful term which is used for something else without having a good excuse for doing so. Call the idea that invisible pixies push atoms around "irreducibility" - or something else - anything!

IMO, "Reductionism" and "Holism" should be reserved for the Hofstadter-favoured sense of those words - or you have a terminological mess:

http://i93.photobucket.com/albums/l76/orestesmantra/MU.jpg

Comment author: simplicio 15 August 2010 08:03:40PM 1 point [-]

Oh, I see. Thanks for clarifying.

Comment author: Perplexed 15 August 2010 07:49:55PM 0 points [-]

You are confusing me, Tim. Above you seemed to be criticizing the usefulness of the second meaning. Now, you seem to be criticizing the usefulness of the first.

Which do you find useless: the label for a methodology, or the label for a hypothesis about the possibility of hierarchical explanations?

Comment author: timtyler 15 August 2010 08:06:09PM *  0 points [-]

a) - good; b) - not needed. (Ref for a and b: http://en.wikipedia.org/wiki/Reductionism)

Reductionism and Holism should be the names of strategies for analysing complex sysytems by reducing them to the interactions of their parts - or considering them as high-level entities - respectively.

The other terminology - the kind used in this post - is very bad. People should not overload such useful terminology - unless there really is no other way.

Comment author: Perplexed 15 August 2010 08:24:19PM 2 points [-]

One windmill I try to avoid attacking is the dictionary. I would suggest you spend a few extra syllables and refer to a. as "methodological reductionism" and b. as "philosophical (or ontological) reductionism". I understand the badness of needless overloading, but I'm not sure I agree that b. is "useless" simply because its validity is obvious to you. Would you also advocate abandoning the term "atheism"?

My problem with philosophical reductionism is I don't know whether it is a claim about the territory or a convention about maps. If it is a claim about the territory, I certainly remain unconvinced, having not yet glimpsed the territory.

Comment author: timtyler 15 August 2010 08:30:00PM 0 points [-]

One can't just let dictionary authors rule language. When they get scientific things wrong, responsible individuals should put up a fight. Look at what is happening to "epigenesis" - for example. Or "emergence".

Comment author: timtyler 15 August 2010 08:32:03PM 1 point [-]

Would you also advocate abandoning the term "atheism"?

That is likely to lead off topic. If the atheists and agnostics could sit down and decide what those terms actually meant, it would certainly help. Meanwhile, call me an adeist.