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TimS comments on How to Not Lose an Argument - Less Wrong
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I did say that I was doing a functional analysis. The social purpose of labeling a scientific statement as true is to differentiate statements that are useful in making accurate predictions from those that are not useful for making predictions. Also, see my response to dlthomas.
If we stop using functional analysis, the question of truth remains. Personally, I have a lot of trouble coming to a satisfying conclusion about the concept, because I think the hypothesis of the incommensurability of scientific theories is strongly supported by the evidence. Notwithstanding that incommensurability, I think that the ability of science to make accurate predictions is based on the regularity of phenomena. I wrote this earlier, which is a slightly more detailed version of the same point.
I may be exposing my ignorance here, but I don't understand what you mean by a "social purpose". The purpose you describe sounds like an entirely pragmatic purpose to me; i.e., it's the one that makes sense if you want to discover more about the world -- but perhaps this is also what you meant ?
I read that comment, and I disagree with its premise: "It's like Aristotle [and Newton] wasn't looking at the same reality". Both Newton and Aristotle (ok, Aristotle not as much) explain not only their conclusions, but the evidence and reasoning they used to arrive at these conclusions, and it's rather obvious why they made the mistakes they made... it's because they were, in fact, looking at the same reality we now inhabit. You'd make the same mistakes too, today, if you knew nothing of modern science but tried to figure out how the world worked.
Furthermore, Newton wasn't even all that terribly wrong (again, Aristotle was a ways off). If I want to predict the orbit of our Moon with a reasonable degree of certainty, or if I simply want to lob a rock across the top of an enemy fortress's walls with my trebuchet, I don't need relativity.
You make it sound as though the "regularity of phenomena" is some kind of a trick that people invented so they could keep getting tenure, or something. I, on the other hand, would claim that it's simply the most parsimonious assumption, given our observations.
It's not a big deal. I was trying to be precise to avoid the appearance of a naive claim like "purpose is an objective property of things," which is clearly false. Purpose is only meaningful as a reference to something, and I'm referencing society.
The Aristotle / Newton comparison is meant to be evidence for the hypothesis of incommensurability of scientific theories. If it doesn't convince you, then I regret that I'm not a good enough historian of science to present additional evidence. (For example, the issues about phlogiston do not seem like compelling evidence for the theory to me, although experts in Philosophy of Science apparently disagree). The only other point in favor of incommensurability of scientific theories is something like "It's awfully lucky that scientific theories are commensurable, because theories of everything that are not scientific (i.e. moral theories) are definitely incommensurable."
Anyway, disbelieving the scientific incommensurability hypothesis (SIH) means that the point about phenomena is not all that interesting or insightful. But if you believe SIH, then the scientific nihilism (i.e. there is no objective reality at all) is very tempting. But scientific nihilism must be rejected because science keeps making accurate predictions. Not only that, the predictions keep getting better <i.e. once we didn't know how to build computers. Now, we do>
So even if we reject the idea of accurate scientific models based on the SIH, we still are committed to some sort of regularity, because otherwise accurate prediction is extremely unlikely. That's phenomena. Sort of the middle ground between scientific nihilism and a belief in the accuracy of scientific models.
Ah, yes, agreed.
I think I might be misunderstanding what the word "incommensurability" means. I thought that it meant, "the performance of theory A cannot be compared with the performance of theory B", but in case of Aristotle/Newton/Einstein, we can definitely rank the performance (in the order I listed, in fact). Aristotle's Laws of Motion are more or less (ok, closer to the "less" side perhaps, but still) useful, as long as you're dealing with solid objects on Earth. Their predictive power isn't great, but it's not zero. Newton's Laws are much more powerful, and relativity is so powerful that it's overkill in many cases (f.ex. if you're trying to accurately lob a rock with a trebuchet). Each set of laws was devised to explain the best evidence that was available at the time; I see nothing incommesurate about that. But, again, it's possible that I'm using the word incorrectly.
I am not convinced that they are. In fact -- again, assuming I'm using the word correctly -- how can theories be incommesurable and yet falsifiable ? And if a theory is not falsifiable, it's not very useful, IMO (nor is it a theory, technically).
As I use incommensurability, I mean that the basic concepts in one theory cannot be made to correspond with the basic concepts of another theory.
At bottom, Aristotelian physics says that what needs to be explained is motion. In contrast, Newtonian physics says that what needs to be explained is acceleration. I assert that there is no way to import principles for explaining motion into a theory that exists to explain acceleration. In other words, Aristotelian physics is not a simpler and more naive form of Newtonian physics. You can produce a post-hoc explanation of the differences like your invocation of the limits of observable evidence (but see this discussion). I find post-hoc explanation unsatisfying because scientists talk as if they can ex ante predict (1) what sorts of new evidence science needs to improve and (2) what the "revolutionary" new theories will look like. And yet that doesn't seem to be true historically.
There is some unfortunate equivocation in the the word theory ("Theory of Gravity" vs. "Utilitarianism: A Moral theory"). But something like Freudian thought is unified(-ish) and coherent(-ish). What is wrong with referencing "Freudian theory"? That doesn't reject Popper's assertion that Freudian thought isn't a scientific theory (because Freudian thought isn't falsifiable). On falsifiability more generally, I'm not sure what it means to ask whether utilitarianism (or any moral theory) is falsifiable.
What about "V = a * t" ? That said, AFAIK "at bottom" Newton didn't really want to explain acceleration, or motion, or any abstract concept like that; he wanted to know why the planets appear at certain places in the sky at certain times, and not others -- but he could pinpoint the position of a planet much better than Aristotle could.
And I think we can, in fact, correspond Newtonian concepts to Aristotelian ones, if only by pointing out which parts Aristotle missed -- which would allow us to map one theory to the other. For example, we (or Archimedes, even) could talk about density and displacement, and use it to explain the parts that Aristotle got right (most rocks sink in water) as well as the parts he got wrong (actually some porous rocks can float).
Nothing really, it's just that most people around here, AFAIK, mean something like "a scientific, falsifiable, well-tested theory" when they use the word.
If it's unfalsifiable, what good is it ? Isn't that the same as saying, "it has no explanatory power" and "it lacks any application to anything" ?
I see utilitarianism as more of a recipe (or an algorithm) than a theory, so it doesn't need to be falsifiable per se.
For theories to be commensurate, you need to be able to move all the interesting insights of each theory into the other and still have the same insight. Sure, Aristotle and Newton seemed to agree on the definition of velocity and acceleration. But there's no way to state "An object in motion will tend to stay in motion" as a conclusion of Aristotelian physics because the caveats Aristotle would want to insert would totally change the meaning.
(As an aside, I'm making a point about the theories, not the scientists. Boyi might find Newton's motivation interesting, but I'm trying to limit the focus to the theories themselves).
The point about moral "theory" is sufficiently distinct that I hope you'll forgive my desire to move it elsewhere just to make this conversation easier to follow.
In this case, I don't think I fully understand what you mean by "insights" being "the same". Any two scientific theories will make different models of reality, by definition; if they didn't, they'd be the same theory. So, if you go the extreme route, you could say that all theories are incommensurate by definition, but this interpretation would be trivial, since it'd be the same as saying, "different theories are different".
I agree that there's "no way to state 'An object in motion will tend to stay in motion' as a conclusion of Aristotelian physics", but that's because Aristotelian physics is less correct than Newtonian mechanics. But there is a way to partially map Newtonian mechanics to Aristotelian physics, by restricting our observations to a very specific set of circumstances (relatively heavy objects, an atmosphere, the surface of Greece, etc.). Similarly, we can map relativity to Newtonian mechanics (relatively heavy objects, slow speeds, etc.). It seems odd to say that these theories are totally incommensurate, while still being able to perform this kind of mapping.
In fact, we perform this kind of reduction every day, even in practical settings. When I want to drive from point A to point B, Google Maps tells me that the Earth is flat, and I implicitly believe that the Earth is flat. But if I want to fly to China, I have to discard this assumption and go with the round-Earth model. I see nothing philosophically troubling about that -- why use an expensive scalpel when a cheap mallet works just as well ?
I was trying to make a point that scientific theories are not just about moving abstract concepts around; their whole purpose is to make predictions about our observations. This is what differentiates them from pure philosophy, and this is also what makes it possible to compare one theory to another and rank them according to correctness and predictive power -- because we have an external standard by which to judge them.
Yeah, that's a good move, no objections here.
But not too heavy...
Haha, yes, very important detail, that :-)
I can't write it better than Feyerabend. My argument about Aristotelian and Newtonian physics is a paraphrase of section 5 of his argument, starting at pg. 94, and ending at about 101.
ETA: And I looked at it again and it's missing 95-96, where some of the definitions are. If there's interest, I'll type it up, because I think it addresses the criticisms fairly well.
Ok, I have to admit that I haven't read the entire book, but only skimmed the section your mentioned -- because my time is limited, but also because, in its infinite wisdom, Google decided to exclude some of the pages.
Still, I can see that Feyerabend is talking about the same things you're talking about; but I can't see why those things matter. Yes, Aristotle had a very different model of the physical world than Newton; and yes, you can't somehow "plug in" Aristotelian physics into Newtonian mechanics and expect it to work. I agree with Feyerabend there. But you could still go the other way: you can use Newtonian mechanics, as well as what we know of Aristotle's environment, to explain why Aristotle got the results he did, and thus derive a very limited subset of the world in which Aristotle's physics sort of works. This does not entail rewriting the entirety of Newtonian mechanics in terms of Aristotelian physics or vice versa, because Aristotle was flat out wrong about some things (a lot of things, actually). Feyerabend seems to believe that this makes the two theories incommensurate, but, as I said above, by that standard the word "incommensurate" becomes synonymous with "different", which is not informative. I think that Feyerabend's standards are simply too high.
I was also rather puzzled by something that Feyerabend says on page 98, toward the bottom. He says that "impoetus" and "momentum" would give you the same value mathematically, and yet we can't treat them as equivalent, because they rest on different assumptions. They give you the same answer, though ! Isn't this what science is all about, answers ?
Let me illustrate my point in a more flowery way. Let's say that Aristotle, Newton, and Einstein all went to a country fair together, and entered the same block-pushing contest. The contestant randomly picks a stone block out of a huge pile of blocks of different sizes, and then a tireless slave will push the block down a lane (the slave is well-trained and always pushes the block with the same force). The contestant's job is to predict how far the block will slide before coming to rest. The contestant will win some amount of money based on how close his prediction was to the actual distance that the block traveled.
As far as I understand, Feyerabend is either saying that either a). Aristotle would win less money than Newton who would win less than Einstein, but we have no idea why, or that b). We can't know ahead of time who will win more money. Both options look disingenuous to me, but it's quite likely that I am misinterpreting Feyerabend's position. What do you think ?