Why is all this ink being spilled over the alleged (im)possibility of reducing Mendelian Genetics to Molecular Biology?

In Uncategorized on February 15, 2010 by toddallinmorman

As an intellectual exercise, this process of reduction has its interest, but the tone of the literature strikes me as a topic people actually care about. At first when contemplating this process it appeared likely that classical Mendelian Genetics (CMG) was the theory left behind in a scientific paradigm shift, as in the kind Kuhn outlined. In such a case we would be leaving behind an outdated concept of genes being the operative what-not that explained the dispersion of traits in organisms. Some of Kitcher’s arguments against reductionism pushed me in that direction. I was pretty much ready to let the concept of gene go entirely as all that outdated nineteenth century thinking.

Then Sober and Waters changed my mind by pointing out that Molecular Biology (MB) has redefined genes and claims that many genes are involved in a complex way to (potentially) account for CMG genes. The difficulty then arises that, as presented, CMG is a little unclear as to what exactly it might be saying. Does it present simple laws or complex explanations that are very organism and trait specific? Depending on how we answer this question, we will get different answers.

For example, if CMG has simple laws that don’t really account for the details of actual observed phenomena, this would be more of a paradigm shift, and we should just move on. The theory does not accurately explain phenomena, and if MB does- it would be disturbing if CMG could be reduced to MB. If on the other hand CMG is a great deal of specific rules, bordering on the order of annotated observations, then it might be a sloppy (by comparison, but still innovative and insightful in its observations) theory, but potentially completely explainable by MB. Much of Sober’s argument hinges on both MB and CMG being ‘correct’ (not being versed in the subtleties of philosophy of science nuance here- I’d say prefer to say ‘viable in the presence of the known phenomena’).

So, it seems to me there are two potential reasons for caring so much about the argument over reduction, and both involve contrasting metaphysical assumptions about the nature of existence. One reason to care about the reducibility of CMG is that demonstrating its reducibility would be to present it as a continuing viable explanation, and negate the position that a paradigm shift had occurred, as the theories are commensurate. This position assumes that there is one ultimate scientific truth of the universe that is (theoretically) discoverable.

The alternate reason to care assumes that CMG is still viable in face of the known phenomena, as well as MB, and proving the impossibility of reduction will demonstrate (or at least aid in preserving the viability of the position of ) the disconnected nature of the various scientific fields. This is naturally a desirable place to be as the implications of full scientific explanation brings up frightening possibilities of an intelligence socially and personally engineering all human outcomes or activity (or alternatively being determined without any purpose). If psychology, psychiatry, and the social sciences are separate from physics, then some form of human agency may be retained (though, I would love a coherent definition of ‘free will’ other than the ‘self-causing thing’).

While the nature of existence will not be determined by the ‘winner’ in an argument over the reducibility of CMG to MB, I guess I can see why someone might care beyond the pure intellectual puzzle of it. Are there less grand (or more grand than the completely banal) reasons for caring so much about this intellectual exercise?


10 Responses to “Why is all this ink being spilled over the alleged (im)possibility of reducing Mendelian Genetics to Molecular Biology?”

  1. One way of looking at it is that it boils down to territoriality. If reductionism works, then all the other sciences …er… “belong” to physics. So anti-reductionism is a way for a field to retain autonomy in the face of “imperialistic” lower-level sciences. How’s that for less-than-grand?

    Note that anti-reductionism doesn’t reject physicalism, just tones it down a little.

  2. Let me start by giving my, perhaps unsatisfying, answer to the question. Ink is spilled because we care (this is my answer for “why” questions about a lot of philosophy). Specifically in this case, we care about the nature of science, which means we care about the nature and relation of scientific theories.

    Now, a couple of musings on your thoughts, Todd. RE: the first possible reason for caring. What I think this reason gets right is that people care about whether CMG is a useful explanation or not. But actually, some who argue against reduction (e.g. Kitcher) argue *from the fact* that it is still a useful source of explanation. Commensurability is not needed for this.

    A further worry is that the reason relies on Kuhn being right. I like Kuhn (honestly!), but he’s not right philosophically, nor does his description of revolutions always capture the sociology of science.

    As to the second potential reason for caring, it is true that some people want to avoid determinism at any cost in order to maintain libertarian free will. However, this does not seem to be the motivation of any players in this case. And Dan is right–one may be a determinist and/or a physicalist while still being an antireductionist.

  3. I certainly was not exploring every possible permutation, only the ones I primarily noticed might have a vital stake in the argument.

    As to the utility of CMG- that may be the case, but it does not change the possibility that a paradigm shift has occurred. It seems likely to me that if reduction is impossible, then there is likely a paradigm shift and we have incommensurate theories. This does not change the utility of CMG.

    For example, Newton is still taught everywhere though it is not accurate in the same way as relativity, but it is ‘close enough’ for all the work we do at such slow speeds here on Earth. Newton has loads of utility, but, as Kuhn pointed out, it would take a great deal of work of approximating the conclusions of Newton from Relativity, and such an exercise would have no practical utility. Just use Newton.

    So, CMG could still retain utility in breeding as being ‘close enough’ or it could be completely correct (still) in the face of known phenomena. In the first case reduction would likely be impossible while in the second case reduction would be likely, if all of science was indeed reducible (and we were on the right track still with MB).

    But, all this seems like a tempest in a teapot if one considers there is likely a better theory out there yet to be discovered that will more comprehensively explain our unfolding understanding of the phenomena that will likely be incompatible with both CMG and MB, the as yet undiscovered ‘Relativity’ of cellular biology.

  4. There are several good questions here, Todd. I hope we get to explore them in depth during the seminar. One question is what is the reductionism/anti-reduction debate about? Is it about explanation? Or, is it deeper, having ontological consequences? What’s the scope of the reductionist/anti-reductionist claims? Is anyone really arguing, as Sober suggests, that anti-reductionists think that *no* higher level science that postulates abstract unifying true laws is reducible? Or is it weaker?

    A more local question you seem to be asking is whether the molecular conception of the gene commensurate (to use Kuhn’s technical term) with the conception of the gene from Classical Mendelian Genetics?

    All very good questions. If you have time for extra readings, my colleague, Zac Ernst, has a nice paper about how genomics has redefined the gene concept yet again:

  5. I second Dan that the debate on reductionism cares about the autonomy of different theories. If mind is reduced to physics, then theories of the mind are not autonomous: the basic cocnepts and laws can be rephrased into the ones in physics.Thus, I take the debate to concern about whether CMG is an autonomous theory.

    Todd talks about the limitations of CMG. I think that these limitations don’t prevent us from realizing the usefulness of CMG, the achievements it has accomplished in explaining many phenomena. At the very least, CMG is not pseudo-science. So, regarding its usefulness and limitations, it makes sense to study whether what it achieves can actually be accomplished by some lower-level sciences, like molecular biology.

    • Wenwen,

      I’m with you that the concern about antonomy of cercain theory is an understandable motivation for the debate on reductionism, but the further question is why we care about the autonomy of CMG.

      Besides the conern about the usefulness of CMG, there might be another reason suggested by the introduction of Waters’s paper. Waters says the relationship between CMG and molecular biology is a paradigm of nonreduction, and it is used in debates about the reducibility of theories in other fields. So the reason why philosophers concentrate on the reducibility of CMG is that if reductionists can disprove that CMG is reducible, the reductionism arguments in other fields will be undermined as well.

  6. Another suggestion for why it matters whether some sciences are reducible to other sciences is that, if such reduction is possible, then this gives us a basis for determining the adequacy of disputed amendments to those sciences.

    For example, if we find that CMG is reducible to molecular biology, and one proposes adding a feature to CMG that isn’t reducible to molecular biology, then our reduction criterion gives us a basis for rejecting that addition. For if reduction of some sciences is possible, then we can filter amendments to those sciences by determining whether such additions are reducible or not.

    However, if such reduction is not possible, then maybe we shouldn’t test the adequacy of proposed features of a theory by looking to whether such features can be reduced to the appropriate lower-level science.

    • Jenny,

      You said:
      “For example, if we find that CMG is reducible to molecular biology, and one proposes adding a feature to CMG that isn’t reducible to molecular biology, then our reduction criterion gives us a basis for rejecting that addition. ”

      I’m curious why it is not the case that if new feature is added, and it is not reducible, then it challenges the reductionability of higher-level theory to lower-level theory.

  7. Just finished reading the Ernst piece. I really liked that he appears to soundly ground the definition of genes within contemporary research. His definition is of the sort (for those who did not read it):

    (1)genes correspond to functional segments of nucleic acids on the chromosome.
    (2)these sequences code for proteins which perform identifiable functions or ‘function roles’.
    (3)genes tend to be conserved- that is inherited as a functional group of the relevant DNA code.
    (4)genes are interchangeable modules- that is the functions produced may serve as different parts of different pathways for more complex cellular chemical reactions or functions.

    While this is a world away from dominant and recessive traits in genotypes, one can see a rough analogous position in the operational theories. Ernst spends a great deal of the paper exploring when names are kept for what are essentially scientific misconceptions (for me an overly formal look- I suspect the actual historical process is a bit more ad hoc and continues to be so). Thus much of the reductionist-antireductionist fight is over the appropriateness of keeping this term ‘gene’.

    For me, Ernst renders the entire conversation on the reduction of CMG null. Quite clearly on page three Ernst states that most of CMG is just wrong, “none of these assumptions have been borne out in the long run…So these Mendelian assumption have turned out to be false.” If CMG is ‘false’ (still good science in the sense that it is not a pseudo-science (like economics or political science)- just supplanted by a much better theory that provides a better explanation for our concerns, and in this case disproven by later known phenmena) then the ability to reduce CMG to MB should be very disturbing. We would be demonstrating the (false) laws of an outdated science (CMG) with the terms and theories of its much better replacement (MB). But using a theory that we hope is better to demonstrate a falsified theory is perhaps to show that new theory to be false as well.

    While I am on board with the viability of the term ‘gene’ now, I am also convinced that this is not a case of higher and lower theory, but of a paradigm shift. MB has pushed aside CMG and CMG is false in the face of known phenomena.

    Ptolemy traced out orbits about the Earth with his beautiful geocentric system. Now the word orbit is used to describe bodies that do not travel in regular circular motion about the Earth, but instead the paths about other heavenly bodies without purely regular circular motion. There is no promise in reducing Ptolemy’s model of the motion of the heavens to modern physics. He had the mechanism and paths all wrong (but, it should be noted that Ptolemy’s system provided better predictions of the locations of observable phenomena than Copernicus as observational skills improved).

    Reducing a false theory is either impossible, demonstrates the reducing theory is false, or is providing us some very interesting information regarding consistency and the universe.

  8. Sheng, I agree with what you said. According to Waters, it is widely accepted that CMG is not reducible to molecular biology.

    As for Jenny’s point, it seems like reflective equilibrium to me. On the one hand, we got some criteria of reduction. On the other hand, we have some intuition about whether a theory can be reduced to another. We want the criteria to match our intuitions. If there is any mismatch, we need to decide what to adjust–the criteria, or the intuition, given the specific case.

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