Showing posts with label prediction. Show all posts
Showing posts with label prediction. Show all posts

Thursday, May 16, 2024

dismal complaint

Originally published on Language and Philosophy, March 2, 2012

Naked Capitalism posts an interview The New Priesthood, with Yanis Varoufakis, a Greek economist who currently heads the Department of Economic Policy at the University of Athens, in which he criticises economics as self-reflexive and unfalsifiable because economists won’t commit to factual prediction of the economic weather.

Whatever troubles the field, his criticism can’t be it.

Empirical observation is a constant chastisement for *all* the sciences, not just economics, but physics or neuroscience or any empirical science. Self-referentiality is no bar to a science: above all logic but also math, neuroscience, linguistics, cognitive science, and many others, refer to their own subject matter. Reflexive hypotheses can be predictive, and their predictions can be tested.

One mustn’t confuse reflective *science* with a reflective regression in *implementation*. Moreover, a regressive theory becomes a reductio of itself if practiced — you can’t implement an infinite regression, so it can play no role among the phenomena.

Implementing theories does complicate the science — but it is not a flaw in economic science. It’s just that the science must attempt to model the consequences of acting on economic hypotheses. But this is also a traditional part of science called trial and error.

It may be an embarrassment to the dignity of human intelligence that many of our scientific advances have been driven by accidents within trial an error, but it is surely not a *failure* of science. It’s an embarrassing success (and usually viewed not as embarrassing but perhaps unjustifiably as brilliance).

In any case, analogizing economists treating a crisis as a surprise meteor undermines Yanis’ own argument. Is cosmology a non science because not every meteor’s location or arrival can be predicted??

Physics doesn’t purport to tell the shape of the next snowflake or when it will begin to rain today. It does tell me why we generally stand on the earth and not float through the air. The problem with economics may be that we expect too much. Just because we ourselves are the agents of our own economy shouldn’t lead us to expect us to predict it any better than any other science. And yet that’s exactly what economists try to do. I think it’s because there is a moral call in the field that is tough to ignore for those who hear it.

The challenge for economics has always been not its lack of predictive ability, of which it has about as much as any natural science, but the moral dimension: Adam Smith long ago pointed out that labor gets shafted in the balance of wealth.

What’s dismal about economics is that the economy often works most efficiently and exuberantly at the price of a human sacrifice. The big question is whether the failures of those who wish to resolve that moral quandary are greater than the occasional crises of the economy. This is also a matter of trial and error.

That undergrads are more cooperative than those who chose to become economists may say more about why students choose economics. The experiment didn’t track those undergrads who went into econ and those who didn’t and what happened to their cooperativeness afterward. So it may say little or nothing about what is taught in economics. In any case, to assume that the personal attitudes of the scientists affect the science is to assume what was to be concluded: that it is a non science. If it is a true science, then the personal biases of the scientists won’t matter (well, that’s an idealization: even physicists take sides on theoretical issues, defend them, promote them and make their reputations on them and get their funding to promote them). Determining whether a discipline is science should depend on its predictive success — its testability — and its simplicity within itself and in relation to other sciences. But bear in mind that the Popper model is also an idealization that doesn’t correspond accurately to the actual practice of even the hardest sciences, even in logic, for example.


hard to believe

Originally published on Language and Philosophy, October 29, 2011

To the extreme positivists who insist that science should stick with the surface data only, not speculative theories, and that science can only describe the world never explain it, here’s another homegrown example to add to your shortcomings.

Standing in the communal shower at the public pool, my pool-friend the anti-Chomskean linguist, put forward his view of the unfortunate fact that the showers always seem to get too hot to bear. I explained that it is likely because the boiler overheats the reservoir of water. If you turn all the showers at once, to draw that hot water reservior out and bring cold water into the boiler reservoir, you’ll notice that the showers will get cooler.

He scoffed. He, instead, goes from shower to shower, using the few seconds of colder water that has been sitting in the pipe, and cobble together a quick shower from among them.

I pointed out to him, that my theory is falsifiable, and I’ve empirically tested it several times. I turn on all the showers; they get cooler. Let the showers stop; the remaining shower gets too hot again. You could even gauge the rough quantity of the reservoir in the boiler, if you could gather the water in the showers — all without actually going to look at the boiler.

He insists that my theory is mere speculation and not science.It’s not true, he says.

So I asked him for his theory of why the water is too hot but sometimes gets cooler. His answer: there are areas of scalding hot water, and areas of cooler water. That’s all.

Notice that this is a no-theory theory. It’s akin to “God likes it that way.” In fact, it leads to that belief. Why is the water hot now or cooler now? Because it’s hot now or cooler now. The dormitive power. This is not predictive, and prediction is the justification of any theory. Truth can’t be the justification of a theory, because we don’t have absolute access to truth. I mean, it could be that the boiler-deity just does what she likes with the water. No theory can disprove that. But to the extent that my theory is predictive, then who needs the boiler-deity even if she exists? I’ve got a better theory: the boiler-deity theory isn’t predictive even if true, while my theory is predictive even if it isn’t true.

That’s science. Holding that scientists believe their theories are true, is probably the reason people balk at scientism. But scientists themselves don’t believe their theories are true, they hold them because they are predictive or because they are consistent with all the other predictive theories or because they are maximally efficient and informative (elegant). Science is not knowledge so much as an investigation into knowledge contingent on evidence, however that is construed. An investigation is a process, not a body of knowledge. What qualifies as evidence is a bugbear. But that’s as much a problem for the extreme positivist as for a theory-builder.


Yet more again (see “Why explain” below)

Originally published on Language and Philosophy, March 19, 2011

Here’s another weakness of empirical inductive statistical observation: it can’t define the range of data to exclude obvious exceptions, exceptions “that  prove the rule” and degraded data. Consider a stuck key on the keyboard. The repetition of letters on the screen has to be included among the behaviors of the key strokes. So the statistical account of the relation between keys and screen letters has to indicate that each stroke can result in multiple letters on the screen. At best it indicates an aberration, but the anomaly doesn’t rise to an indication of failure. It’s just a falsification of the inductive inference. Uninformative.

If you have a description of the machine independent of the stroke-letter correlation, you can systematically rule stuck key behavior out of the data set of machinery-ideal behaviors. The exceptional repetitions are now “mistakes” derived from machinery malfunctioning.

The same applies to linguistics. If the linguist, following Bloomfield or Diver, takes English to be all the utterances of English, how rule out stuttering utterances, stumbling utterances, half-finished sentences? What about utterances spoken by non native speakers who barely know English? How can the empirical purist rule out those speakers?

The generativist has a principled answer. Her account of English is based on a description of an independent phenomenon, the brains of English speakers. The account of those brains in turn depends on an independent description of brain evolution. And it goes like this:

1. All normally developing humans and only humans have this kind of language. Therefore, it is a species trait.

2. Humans learn language without being taught it — they learn it just by exposure. Therefore it is an instinct (via imprinting, “imprinting” broadly defined, along with internal extrapolation and selection).

3. Humans learn language during the maturational period. Therefore native language can be roughly defined by imprinting, selection and extrapolation during the maturational period.

From these three, it follows that only native speakers of English have command of the natural language. And since comprehension is part of the language capacity, the degraded data can be described as mistakes, the utterances of non native speakers can be excluded, and there is no circularity in defining the speakers (the circularity of the definition of English speakers was an embarrassment of the empiricist).

Hempel and Goodman point out the importance of counterfactuals and subjunctive conditionals for laws. But neither of these establish the authority of a law. Of course it’s true that a law provides counterexamples and subjunctive conditionals that mere statistical descriptions can’t. But what justifies the application of the counterfactuals and conditionals? No mere inductive generalization can support a counterfactual beyond mere conjectural hypothesis. What licenses the law is the independent background theory — the description of some other phenomenon that defines and determines the explananda. Newton’s laws of motion are a theory about bodies, not about special planetary motions. The theory of bodies explains the planets and at once categorizes planets as independent bodies like all other independent bodies, not special objects set in Aristotle’s rotating spheres. The independent background theory explains and redefines the phenomena, categorizing them and identifying those that belong and why those that don’t don’t.

If the key were to get stuck, the letters would repeat on the screen. If an utterance were spoken with prepositional phrases embedded with cross relations over its embedding, it would be incomprehensible. The machine explains.


Follow up on Weinberg (see previous post below)

 Originally published on Language and Philosophy, March 16, 2011

To finish up: Weinberg sets out the problem of explanation as a question of fundamentality, generality and derivation. Are Newton’s laws more fundamental than Kepler’s? Maybe not, if the laws are derived from Kepler’s orbits. And Kepler’s orbits, he points out, apply to electrons where Newton’s don’t, so we can’t easily determine which are more general.

I’m suggesting that these are not the right questions at all. It’s a question of, well, questioning. When the purely descriptive inductive inference is falsified, there is no question to ask. You can’t say, why did the key fail? You’ve simply got a statistical degrading. But if you’ve got a theory about the machinery, then you can ask “what went wrong with it?” Then you can fix it. That’s what “why” is all about. How to fix.

When you have a background hypothesis that is more than just a statistical correlation among phenomena, that’s when you can ask, “why?” Conversely, if you ask “why?,” you’re appealing to some hypothesis beyond the statistical description. The two approaches, empirical and generative/law-governed, give very different answers to “how does it work?” One leads to a successful fix, the other to an inferential failure.

To be fair, Weinberg recognizes up front that explanation is part of what science does, and he criticizes those who try to eliminate explanation by reducing it to mere description general or description fundamental or description derivational. As he says, it’s not for scientists to redefine our common language words. If a scientific explanation happens also to be a description, then it is both a description and an explanation: a description of a broad range of phenomena that the description classes together; and, sometimes just by virtue of classing them together, an explanation of those phenomena. No reason for description and explanation to be mutually exclusive.

But I think that those explanations that do no more than categorize — this flower inclines towards the sun because all flowers incline towards the sun — may be explanatory, but it’s little more than a broader inductive generalization. It gives a sneaking feeling of question-begging. Why does this flower incline? Because all flowers do. But why do all flowers do? Somehow, the inductive generalization hasn’t got beyond just describing. Why does this flower incline? Because it’s a flower. Why is it a flower? The answer to that will likely be genuinely circular unless there is a deeper hypothesis, like photosynthesis, than “flowers incline to the sun.”

I don’t see why it would matter whether photosynthesis is more general than inclining, or whether scientists discovered photosynthesis by deriving it from inclining, or whether inclining is more fundamental than photosynthesis. What’s important is that the explanation appeals to something other than flower behavior. Photosynthesis is a phenomenon independent from the flowers. It’s not about the mere inclinations. The science of photosynthesis regards a separate theory, and that theory added to the knowledge of flowers predicts the behavior the empiricist observes among the flowers. But the empiricist doesn’t observe photosynthesis directly. Photosynthesis does not logically require inclinations at all. It’s about sunlight and chemical transformations.

A true non-question begging explanation has to appeal to a theory that is separate from the mere observation.

Now, the curious may ask, so why is there photosynthesis? And there should be a further answer reaching back into genetics, and if the curious ask about that, there should be a further answer reaching even further into basic chemistry and physics, and, if we keep asking, we may get to a final answer about the fundamental physical “laws of nature.” And it’s likely that someday we won’t be able to ask “why” any further. But it won’t be because we don’t know how to look beyond. It’ll be because the universe is just so and there isn’t anything beyond. Maybe.

Will that end in circular answwers and question-begging? I guess, but at least it won’t be our fault.