On the (dis)unity of the sciences? (from sadly defunct Scientia Salon)

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sciborg2

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« on: November 30, 2018, 09:43:17 pm »
It's sad Massimo Pigliucci's Salon didn't manage to keep going, it was a great collection of articles. He even was willing to entertain articles against his own materialism like the Peer to Peer Simulation hypothesis...

Anyway here's one I liked by him personally ->

On the (dis)unity of the sciences

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...But what does “reducing” mean, anyway? [4] At the least two things (though Fodor makes further technical distinctions, you’ll have to check his original article): let’s call them ontological and theoretical.

Ontologically speaking, most people would agree that all things in the universe are made of the same substance (the exception, of course, are substance dualists), be it quarks, strings, branes or even mathematical relations [5]; moreover, complex things are made of simpler things. For instance, populations of organisms are nothing but collections of individuals, while atoms are groups of particles, etc. Fodor does not object to this sort of reductionism, and neither do I.

Theoretical reduction, however, is a different beast altogether, because scientific theories are not “out there in the world,” so to speak, they are creations of the human mind. This means that theoretical reduction, contra popular assumption, does most definitely not logically follow from ontological reduction. Theoretical reduction was, of course, the holy grail (never achieved) of logical positivism: it is the ability to reduce all scientific laws to lower level ones, eventually reaching a true “theory of everything,” formulated in the language of physics. Fodor thinks that this too won’t fly, and the more I think about it, the more I’m inclined to agree.

Now, typically when one questions theory reduction in science one is faced with both incredulous stares and a quick counter-example: but look at chemistry! It has successfully been reduced to physics! Indeed, there basically is no distinction between chemistry and physics! Turns out that there are two problems with this move: first, the example itself is questionable; second, even if true, it is arguably more an exception than the rule.

As Michael Weisberg  and collaborators write in the Stanford Encyclopedia of Philosophy entry on the Philosophy of Chemistry [6]: “many philosophers assume that chemistry has already been reduced to physics. In the past, this assumption was so pervasive that it was common to read about “physico/chemical” laws and explanations, as if the reduction of chemistry to physics was complete. Although most philosophers of chemistry would accept that there is no conflict between the sciences of chemistry and physics, most philosophers of chemistry think that a stronger conception of unity is mistaken. Most believe that chemistry has not been reduced to physics nor is it likely to be.” You will need to check the literature cited by Weisberg and colleagues if you are curious about the specifics, but for my purposes here it suffices to note that the alleged reduction has been questioned by “most” philosophers of chemistry, which ought to cast at least some doubt on even this oft-trumpeted example of theoretical reduction. (Oh, and closer to my academic home field, Mendelian genetics has not been reduced to molecular genetics, in case you were wondering [7].)

The second problem, however, is even worse. Here is how Fodor puts it, right at the beginning of his ’74 paper:

“A typical thesis of positivistic philosophy of science is that all true theories in the special sciences [i.e., everything but fundamental physics, including non-fundamental physics] should reduce to physical theories in the long run. This is intended to be an empirical thesis, and part of the evidence which supports it is provided by such scientific successes as the molecular theory of heat and the physical explanation of the chemical bond. But the philosophical popularity of the reductivist program cannot be explained by reference to these achievements alone. The development of science has witnessed the proliferation of specialized disciplines at least as often as it has witnessed their reduction to physics, so the wide spread enthusiasm for reduction can hardly be a mere induction over its past successes.”

I would go further than Fodor here, echoing Dupré above: the history of science has produced many more divergences at the theoretical level — via the proliferation of new theories within individual “special” sciences — than it has produced successful cases of reduction. If anything, the induction goes the other way around!

Indeed, even some scientists seems inclined toward at least some bit of skepticism concerning the notion that “fundamental” physics is so, well, fundamental. (It is, of course, in the trivial ontological sense discussed above: everything is made of quarks, or strings, or branes, or whatever.) Remember the famous debate about the construction of the Superconducting Super Collider, back in the ‘90s? [8] This was the proposed antecedent of the Large Hadron Collider that recently led to the discovery of the Higgs boson, and the project was eventually nixed by the US Congress because it was too expensive. Nobel physicist Steven Weinberg testified in front of Congress on behalf of the project, but what is less known is that some physicists testified against the SSC, and that their argument was based on the increasing irrelevance of fundamental physics to the rest of physics — let alone to biology or the social sciences.

Hard to believe? Here is how solid state physicist Philip W. Anderson put it already in 1972 [9], foreshadowing the arguments he later used against Weinberg at the time of the SSC hearings: “the more the elementary particle physicists tell us about the nature of the fundamental laws, the less relevance they seem to have to the very real problems of the rest of science.” So much for a fundamental theory of everything.

Back to Fodor and why he is skeptical of theory reduction...

TLEILAXU

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« Reply #1 on: November 30, 2018, 10:44:37 pm »
Not even physics has been reduced to physics.

sciborg2

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« Reply #2 on: November 30, 2018, 11:18:44 pm »
Not even physics has been reduced to physics.

Good point!