Friday, November 18, 2011

Triumph of the Darwinian Method, further thoughts

We recently posted on Michael Ghiselin's book The Triumph of the Darwinian Method, because although this is a decades-old book its ideas are cogent, still timely, thought-provoking, and well expressed.  This is a follow-up.  We don't want to do a review of a 50-year-old book, that we stumbled upon when one of us (Ken) was clearing out a storage space so it could be demolished as part of renovation of our building to accommodate a new faculty member here.  But browsing the book led us to reflect on a few issues, because while there has been a ton of evolutionary history and philosophy written since then (and before)  this one's still worth reading.

The title is about method, and much of his discussion is of the way that so much in biology can be analyzed by considering the accumulation of traits over evolutionary time, and the divergence of organisms (and the patterns that make them) from common ancestry. This is certainly correct.  But Ghiselin seems to go further, to suggest that Darwin's greatest contribution was natural selection, and he discusses in what seems to be a rather inconsistent, though interesting, way what we mean (or Darwin meant) by 'laws of nature' and whether or how such things actually apply.  Inconsistent in that there are different ways to define what a 'law' is or whether we in science are actually seeking to identify such things.  Ghiselin takes what seems to be a fully pragmatic 'engineering' approach to science.  He didn't seem to aspire to understanding the real laws of nature, but to be satisfied that any time in history can only have its best-current models of things that frame research designs and interpretation.  Efforts at deeper exploration he seemed to suggest are rather metaphysical.

One can differ about whether this modest and pragmatic goal is the important or indeed perhaps the only possible goal, as opposed to the conceit of hoping to understand the true nature of Nature.  But his book provides a very sophisticated view of the nature of the method of thought that Darwin introduced.  Published in 1969, nearly 45 years ago, this was before we knew nearly as much as we do now about genes and genetics and the evolution of genomes.  But the fact that the arguments are still cogent shows that despite a lot of new knowledge, the conceptual framework has not required basic change.  That in itself is a profound thing to understand, regardless of how much one might quibble with, or complain that most people are not quibbling with, in genetics and evolutionary biology today.

Darwin is credited with using the hypothetico-deductive (HD) method, which is correct as far as it goes, because much of biology was rooted in other kinds of metaphysical worldviews.  Creationism, in that context, has no 'method' because it claims perfect truth (so it also isn't 'science').  But Darwin didn't invent the HD method. It was being developed in physics, chemistry, geology, and even in some areas of biomedical sciences.  And others in geology and even also in biology were using similar methods at the time.  Even if the term itself wasn't invoked.

So Darwin was a product of his time in that sense.  What made him so influential was that life had been considered, in a way, as being somewhat outside of that  kind of analysis, and he showed how to bring it under the same tent.  In particular, of course, he made it clear to most people in science that humans were part of Nature: our exceptionalism as claimed by religious doctrine was simply incorrect.

The 'Darwinian' method is powerful, but the history of its use also has a more questionable side.  And in that, Mendel and the founders of the 'modern synthesis' are inadvertent co-conspirators.  We have been given such strong conceptual guidelines by the triumphant legacy of evolutionary thinking, that we are often rooted in viewing life in highly deterministic, selectionist and mendelian terms that we have ignored one of the most important aspects of really innovative science.  We intensely study what we think we can see implicitly and often even explicitly through these one-explanation lenses.  But that means we aren't paying nearly enough attention to what's 180 degrees different from that:  what we don't know or  perhaps we cannot explain through these particular lenses.

Nothing we know of is inconsistent with evolution as an historical process by which life has coursed through its history.  But clearly not everything is due to natural selection, and genes are clearly not as deterministic as is usually assumed without question.  Instead of continuing to do more of the same, and declaring victory in the battle when there is really little more than some small skirmish victories, we should be somehow encouraging bright younger scientists to think about other aspects of biological causation.  It's been a common theme here at MT.

What kinds of 'laws' apply to biology is a profound question, in particular given the finite nature of populations and the role of probability in the action of genes, and the survival and reproduction of individuals, in a probabilistically changing environment.  Most theoretical treatments sweep much of this under the rug (if not entirely away) in order to get a feeling of mathematical rigor in evolutionary explanations.  But we know that this is imprecise at best.  It seems likely that the 'Darwinian method' of studying biological function as a product of history (including the organs and cells in a body as a product of its individual life-history) is correct.  But that's not enough.

However, don't look here for answers.  Look to students--and do your best to confuse them with enough uncertainty and nervousness about accepted answers, that they aren't afraid to ask:  "What if it isn't true?"**

**But here we are not suggesting that there is even a scrap of actual evidence that the basic idea of evolution and life as a historical, material process isn't generally correct.


Holly Dunsworth said...

Thank you for this post!

Charles said...

This is a nice review. After Darwin, and indeed towards the end of his life, he had to draw his horns in a bit; good on earthworms - pure natural history - and bad on genetics. Nevertleless he precondtioned a debate that would take place nearly a hundred years later and the limits of genetical determinism had be subsumed into straight Darwinian theory.

I think, if Darwin came as a student to a modern biology course with his early predisposition to believe in God and in particular that revealed by Anglican conformity, he would still end up understanding and even amplifying his own theory.

Ken Weiss said...

Thanks for these thoughtful comments. It is interesting that his theory was so robust in general--and to me the core reason was as much common ancestry as it was natural selection--that it could survive essentially Larmarckian ideas about inheritance. I think there is still a strong tendency to genetic determinism even though we know better or, at least, that what genes do to phenotypes more complex than single coded proteins is still rather elusive.

I'm not clear about your second point or how it relates to your first, but if I understand you I think he would certainly have understood life as an evolved phenomenon, and would have no trouble at all in digesting the causal complexities.

That is why, to me, when I hear people talking about new life science discoveries leading to 'paradigm shifts', I think that is actually wrong. We are adjusting our 'paradigm' (basic theory) of life, but its core has stood the test of time.