thinking makes it so

There is grandeur in this view of life…

Not thumping but pumping

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One of the frustrating things about Reinventing the Sacred is that it keeps flip-flopping between condensed accounts of areas of science and mathematics I don’t understand well enough and logical leaps which don’t seem justified. So I keep flip-flopping in turn between wondering if it’s my ignorance that’s the problem and wondering if the logical leaps really don’t make sense.

[Follows Reductio ad Professor Plum as fifth in a series on Stuart A Kauffman’s Reinventing the Sacred which began with Reinventing the sand dune.]

Carl Gustav Hempel

Carl Gustav Hempel

Things come to a head in Chapter 4: The Nonreducibility of Biology to Physics. Here Kauffman picks up an argument which I think is originally from Carl Hempel in his essay Aspects of Scientific Explanation (1965). I don’t have this with me so I’ll stick to what Kauffman himself says:

If Darwin were asked, “What is the function of the heart?” he would answer, “To pump blood.” But hearts also make thumping sounds … yet these sounds are not the heart’s function. Roughly, Darwin’s claim is that the causal consequence for which hearts were selected was their capacity to pump blood, which conferred on the organisms with hearts a selective advantage…

…So we reach an important insight: the function of a part of an organism is typically a subset of its causal features.

We need to follow where Kauffman thinks he’s going with this:

[L]et us grant, for the sake of discussion, that [a] physicist could deduce all the features of the heart from string theory [this would be Kauffman’s paradigm for ‘reduction’ – if it actually worked]. Then what? The physicist would deduce virtually all the properties of the heart [ie including the thumping sounds it makes as well]. She would then have no way whatsoever to pick out, from the entire set of the heart’s properties, the pumping of blood as the causal feature that constitutes its function…

…(Note that functions in this biological sense do not exist in physics.)…

Put like this I am not sure if ‘functions in this biological sense’ actually exist in biology either.

Human heart

Human heart

Many years ago when I was an undergraduate reading Natural Sciences we had books and courses with titles like ‘Cell Structure and Function’ and ‘Invertebrate Structure and Function’. I remember being struck at the time by an ambiguity in that word ‘function’. I couldn’t work out if the ‘function’ of something was the answer to ‘What does it do?’ or the answer to ‘What is it for?’. Or when it was half of that beautiful alliteration ‘structure and function’ did the two meanings melt into a rich new composite just right for biology?

‘What does it do?’ and ‘What is it for?’ are two very different questions. The minute we discount any idea of an intentioned ‘designer’ in nature, the idea of ‘function’ as the answer to ‘What is it for?’ can only be metaphorical, whereas function as the answer to ‘What does it do?’ can be as literal as you like.

Talk of the ‘function’ of (say) an individual organ in an organism is a carryover from teleological thinking. This is fine as long as we don’t smuggle teleology in through the back door.

Imagine a depression in an otherwise flat surface of rock. In wet weather it will fill with rain. Does that mean its function is to catch rainwater and make a pond? That would be a strange use of language. But catching water is what it does.

So why do we feel (just about) justified in saying ‘the function of the heart is to pump blood’ if we can also put our hand on that same heart and say we do not in any way imply the heart was designed to pump blood? I think it is because we see the body it is a part of as if it was designed, and therefore see the part the heart plays in the whole.

Until the theory of evolution by natural selection there was no coherent solution to the puzzle of apparent design in nature, other than by positing an actual designer. But with evolution by natural selection we have, if not a complete answer, at least a conceptual framework which the ever-accumulating evidence fits into.

The heart argument tries to attack that conceptual framework. The claim is that we cannot separate the pumping of blood as the causal feature (the ‘function’) which the heart was selected for, from other features like its colour and the sounds it makes.

But this is a practical issue, not a conceptual issue. In another scientific context, if we wanted to establish if it was feature F1 or feature F2 or feature F3 of an object (or substance or event) which gave rise to result R, we would try a controlled experiment. We would take F2 and F3 out of the equation and see if R still happened. So for example if we had a radioactive sample of river-water we might try a process of elimination to see if only one of the substances dissolved in it was to blame, and which one it was.

In theory (and I mean in theory) we could do the same with the heart. We could in theory manipulate the DNA of some poor laboratory animals to give some of them green hearts, some of them silent hearts, and some of them hearts with a defective pump action. We would then track enough generations to see if any of these changes affected their reproductive survival. So in theory we could establish if it was the pumping or the thumping which gave creatures with hearts their selective advantage.

The practical (let alone ethical) implications of such a research project would make it unthinkable.

Escherichia coli: electron micrograph

Escherichia coli: electron micrograph

But take a different example – say metabolic pathways in the Escherichia coli bacterium. The E. coli genome would be more manipulable – as would its environment – and its fast lifecycle would mean we could assess many successive generations. We would have to pick analogues of ‘the heart pumps blood’ and ‘the heart makes thumping sounds’ – like ‘enzyme E1 synthesises protein P1’ and ‘enzyme E1 creates by-product B1’. But the heart example and the E. coli example would be identical in all important respects.

We could possibly generate:

(i) A viable strain of E. coli where enzyme E1 still synthesised protein P1 but didn’t create by-product B1;

(ii) A non-viable strain of E. coli where enzyme E1 didn’t synthesise protein P1 but still created by-product B1; and

(iii) A non-viable strain of E. coli where enzyme E1 didn’t synthesise protein P1 or create by-product B1.

Results like these would bring us close to being able to say that synthesising protein P1 is the ‘function’ of enzyme E1 because synthesising protein P1 is what enzyme E1 was selected for.

This is what ‘function’ boils down to in biological contexts like these. The ‘function’ of a component (eg the heart or enzyme E1) just is what it was selected for. The E. coli example shows we can at least sometimes separate this ‘function’ from any of other features of the component. But only in a very metaphorical way is its ‘function’ the answer to ‘What is it for?’.

More next time

© Chris Lawrence 2011.


7 Responses

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  1. Thanks Mark.

    Good point – but then ‘reason’ also has (at least) two possible meanings or ‘flavours’. One incorporates intention (the reason I put my hand up was to ask a question) and the other one doesn’t (the reason you can’t see the sun at night is because it’s on the other side of the earth).

    Thanks again, Chris.

    Chris Lawrence

    25 June 2011 at 9:08 am

  2. In my view, Chris, your ambivalence with respect to “Reinventing The Sacred” stems from from flaws in Kauffman’s reasoning rather than limitations of your own knowledge. Your critique is very well-presented.

    There is a serious sticking-point in most discussions of this kind. It arises from our natural anthropocentricity. The very same feature that has over the ages generated anthropomorphic projections that have led to interpretations of natural processes in terms of spirits, deities and the like. Mere reflections of our own mental processes that result from our prodigious imaginations.

    A pertinent example of this is the notion that “design” implies a “designer”. We are saddled with this seemingly obvious belief because we think of ourselves as “designers”. While, in an everyday sense, this is a useful perspective, at any more fundamental level it leads us astray.

    When we try to interpret natural processes in terms of “function”, in its “what is it for” sense, we almost invariably jump to the picture of a homunculus, a little (or big!) guy something along the lines of ourselves, or at least of the mental processes that we introspect, pulling the strings.

    I agree that use of “function” in this way is a metaphor. But, if you dig deep enough, all our thinking is metaphor – electrochemical representation in our brains of the external world. We can’t avoid metaphor but rather need to use it carefully.

    So am I trying to smuggle teleology in the back door? You could put it that way, I guess. But I would rather say that teleology has been there all along. Not the traditional variety with all its mystical baggage. That, quite rightly, has been rejected by those of us who rely upon accounts of nature based upon empirical information. Unfortunately the baby has perhaps been thrown out with the bathwater!

    Stripped of homunculi, initial and final causes, what remains of teleology is, I believe, a very useful tool for interpreting the very high degree of directionality observed in natural processes. Extending through such phases as stellar nucleosynthesis, the evolution of mineral species, biology and, most recently, technology.

    All of which can, in this way, be very parsimoniously regarded as the workings of an autonomous mechanism.

    This model is expanded upon in my latest book “The Goldilocks Effect” which is a free download in E-book formats from the “Unusual Perspectives” website.

    Peter G Kinnon

    18 June 2011 at 10:53 pm

    • Thanks Peter for your considered response.

      I think I am both sceptical and open-minded about ‘directionality’ in natural processes – if that isn’t too much of a contradiction in terms!

      I will certainly take a look at The Goldilocks Effect.

      Thanks again, Chris.

      Chris Lawrence

      25 June 2011 at 8:54 am

  3. Thank you again, Chris, for this thought-provoking post. I’ve never thought about the subtle difference between the questions “what does it do?” and “what is it for?” But as I read this post, it seemed to me that it is, indeed, closely related to the question of reductionism and emergence. And the whole discussion, it seems to me, points to the difficulties science in almost every field – even physics – has with prediction as compared to explanation. Science is much much better at explaining how things happened in the past than in predicting what will happen in the future, even though it is the same laws that should control both.

    Terry Sissons

    18 June 2011 at 9:37 pm

    • Thanks Terry.

      The irony is of course that the scientific method is based on prediction. To ‘prove’ a hypothesis you make predictions based on it and see if they are borne out…

      Chris Lawrence

      19 June 2011 at 5:57 pm

      • Chris –
        You call it an irony. I think it’s a bombshell!

        Yes, I know: accurate prediction is the acid test of a scientific theory. It’s why the search for the Higgs Boson is so important to the Standard Theory of the universe, isn’t it? And why the possible discovery of an unpredicted particle by the Fermi lab in Illinois is potentially disruption. We might have to start all over again when it comes to physics. And that’s the most advanced of our sciences. I increasingly suspect the broad failures of prediction in so many of the scientific disciplines may require a profound rethink of just what science can and cannot do.

        But I say this quietly. For myself, I have known for a long time that scientific “fact” is not absolute, and I am well aware of how many “facts” have been discarded and replaced with new ones in the last three centuries. I love science, but I know it doesn’t save us from living in a state of ultimate uncertainty. (I have often felt comfortable using the word “mystery,” here, but these days I feel it’s perilously close to words like sacred and divine which, as you know, make me nervous.)

        In a way, I don’t fear uncertainty as much as I fear those who want to replace the uncertainty of science with the certainty of faith. Especially if they want to impose their certainty on the rest of the world.

        Thank you –

        Terry Sissons

        20 June 2011 at 2:13 pm

  4. Chris, yes, “The ‘function’ of a (biological) component (eg the heart or enzyme E1) just is what it was selected for.” But can’t we more generally simply say that the function of any component of a system, biological or not, is the chief reason (or reasons) it exists in their systems? (This seems to me more clear than “the function of a part of an organism is typically a subset of its causal features”.)

    Then, contrary to Kauffman, we (or reductionist string theorists) can sensibly talk about the functions of hearts, cultural moralities, and internal combustion engines as the chief reason (or reasons) they exist in their systems.

    I am glad you are reporting on your efforts to make sense of “Reinventing the Sacred”. I tried but gave up in frustration.

    Mark Sloan

    18 June 2011 at 7:49 pm

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