Thursday, February 26, 2009

Reduction Then and Now

As Eric Schliesser explains in his recent post and comments, the old Unity of Science project is dead. That project had two main aims. One of these was to reduce the substantive claims of all science to those of physics. For instance, biology was to be shown to arise from biochemistry, biochemistry in turn from physics. In order to achieve this, the terms of the “special sciences” had to be reduced to those of physics: gene to DNA segment to some physical term. In short: all causal claims were to be reduced to claims about the entities of physics, and the special sciences themselves are reduced to sets of existential claims about certain combinations of the entities of physics.

This project died with the autonomy of science movement. Hilary Putnam, Jerry Fodor, and Philip Kitcher all argued that the claims of the special sciences did not depend in any way on the reduction to physics, and that the causal claims of these sciences could hold independently of their physical realization. For instance, Mendel’s Laws depend only on the independent segregation and recombination of genes, and their underlying structure is unimportant. This meant that the original unreduced meaning of the term gene was indispensable to biology, and the whole reduction process described above is nugatory.

In recent years, we have seen two rather controversial developments in this area – and because of the weakness of general philosophy of science they have not been properly scrutinized from the perspective of scientific methodology.

The first development is autonomy gone ontological. One example occurs in philosophy of biology where it has been claimed that natural selection and drift are “population level causes” in the sense that they act on populations in a way that has nothing to do with causes that act on individual organisms. This goes much further than the claim that populations (cp genes) are constituted by structural features that are indifferent to particular realizations. This is an extreme application of the autonomy arguments.

The second development is ontology being pushed deeper than physics. In the 1920s, Bertrand Russell argued that the terms of physics are functional: mass is nothing but resistance to acceleration; charge, once again, is to be understood interactionally. He asked what intrinsic properties of matter underlay these functional terms. Russell proposed a “neutral monism” in answer to this question, on which the fundamental properties of matter were the stuff of consciousness.

Recently, this proposal has been revived by David Chalmers and Daniel Stoljar, who suggest that the fundamental and intrinsic properties of matter are “protophenomenal”. Consciousness arises out of these deep properties of matter, as do the interactional properties described by physics. This seems like a radical application of the old Unity assumptions.

Both these developments beg for the critical discourse of general philosophers of science. C’mon girls and guys: where are you? Are these uses of Unity/Disunity of science maxims legitimate?


  1. But surely not. the developments you describe are a project in speculative metaphysics, and the Unity of Science folk would have had nothing to do with that. There's a profound difference between ontological reductionism and methodological/semantic reductionism.

  2. The developments I mention present themselves as simple scientific (protophenomenality) or metascientific (population level causes) moves. But I see in your comment the kernel of precisely the kind of general-philosophy-of-science critique that (in my view) is badly needed.

  3. This meant that the original unreduced meaning of the term gene was indispensable to biology, and the whole reduction process described above is nugatory.

    It depends how broad the scope of "biology" is. If the scope of biology is sufficiently narrow then it is perfectly acceptable to talk about genes and never mention DNA. If, however, "biology" includes such questions as what determines mutation rates, then it is essential to talk about DNA and how it interacts with other chemicals, cosmic rays, etc. That is, there are phenomena for which both our evolutionary model and our particle physics model speak to. What is important is that these models be compatible (lest they make conflicting empirical predictions), and showing compatibility requires translating the terms of the models.

    Viewing selection as a "population level cause" further restricts the applicability of the evolutionary model. That is, in some cases (say, very small populations) the action of of selection on individuals becomes important, and attempting to make predictions based our simplified selection-acts-on-the-population model fails empirically. Being of an anti-realist bent myself, I can't get very excited about which ontology is best.

    I'm not very certain just what Chalmers and Stoljar are proposing -- can you give a reference? I'm imagining, however, something like a little burst of qualia accompanying every photon exchange. This is a perfectly legitimate physical theory, except that we have no idea how to test it. Such speculations will probably remain metaphysics for the foreseeable future.

  4. Three unrelated remarks on this post:
    First, Mohan, is your point that there are compelling methodological arguments against certain forms of group selection and that these arguments are blocked by (nefarious) appeals to the (methodological) autonomy (and self-justifying nature of the norms of evidence) of a special science? If so, what do such methodological arguments look like these days? Wouldn't some such arguments run into a pragmatic objection ("'group selection' is mathematically and empirically a useful concept and who are you -- arm-chair philosopher -- to tell us how to do science, etc.")?
    Second, in response to Phil's and Mohan's little exchange: various strands of Australian metaphysics tend to present themselves as versions of scientific naturalism. In general, I am suspicious of such a move if it blocks consideration of science. But if Chalmers/Stoljar style metaphysics is offered as an interpretation/response to science and encourages further empirical research, what's wrong with that? Isn't that a nice job for a philosopher?
    Third, it's interesting to me, Mohan, that you tend to read the old unity program as an ontological project. I actually think that Carnap (et al) thought that ontological unity was a far-off pipe-dream. (I haven't looked at Hempel recently-maybe he does offer ontological reduction?) This is why they offered proposals for semantic/logical/linguistic unity.

  5. A couple of comments.

    First, as I said to Phil, I think that this exchange tends to confirm my feeling that GPOS people should get involved in some of these issues.

    Putting that aside, the Chalmers/Stoljar proposal is a response to certain dualist puzzles. There is for instance Joe Levine's claim that no amount of physical information will EXPLAIN why blue looks the way it does. Chalmers and Stoljar seek to close this "explanatory gap" between qualia and physical reality by supposing that "protophenomenality" universal intrinsic property of matter.

    I didn't say there was anything wrong with this. My suggestion was simply that there are a number of GPOS questions here. First, what kind of explanation is Levine talking about? (I don't mean this as an exegetical question, but as a critical one.) Secondly, what is an "intrinsic" property of matter? In one sense, you might think this is unobservable, because it is supposed to be responsible for, but not definable in terms of, interactions. Third, what is the proper way to formulate universal laws involving intrinsic properties?

    With regard to selection again, the question is not so much a scientific one, but one that concerns the ontology of natural selection. I won't elaborate, so as to keep this comment at a manageable length.


  6. Erich, very briefly, I don't have much riding on taking Unity of Science as an ontological project. But I do think that e.g. describing biological entities in physical terms, and bringing them under physical laws, does have ontological consequences.

  7. Anyone for biosemiotics? Luis Rocha, Claus Emmeche?

    With or without the whole Constructivist megillah.

  8. Another development that might be cited is the growth of philosophy of chemistry, which would not even exist as a discipline if chemistry were fully reduced to physics. Moreover this is the reductive step that is usually assumed to go through without any problems. If not even chemistry reduces to physics, this is more damaging for the reductive program than the claim than say biology or consciousness does not reduce to physics.

    Several philosophers of chemistry have examined whether parts or even the whole of chemistry reduces to physics as was claimed in 1929 by the physicist Paul Dirac. The conclusion is a resounding "NO", although I personally believe that a more nuanced approach is needed in which the considerable success of the reductive enterprize in taken into account in the field of chemistry. It is not a matter of "yes" or "no' as some authors seem to believe. I would be happy to provide references.

    eric scerri