Can Biology Dispense with Purpose?

June 27, 2009

by Gene Callahan

Mario called into doubt the usefulness of purposive explanations in biology in this thread. I started to write up the following as a comment, but it grew long enough, and, I hope, of enough general interest, that I found it appropriate to elevate it to “post level.”

I think the evidence is very strong that biologists just have not been able to do without thinking of the “purposes” of biological features, despite the scientistic prejudice against regarding any such consideration as scientific. (Note: The previous and all future scare quotes in this post are introduced to indicate the disputed and possibly merely metaphorical usage of the terms in scare quotes, so that I am not guilty of petitio principii.) For instance, the semiotician Thomas Sebeok has noted the many ways in which semiotic analysis has enhanced biological understanding, and has concluded that the primary characteristic of life is that living things engage in semiosis. For example, single-celled organisms “interpret” a chemical gradient, with “memories” lasting up to a few seconds, so as to direct their movement away from toxins and towards nutrients. Similarly, in more complex creatures, the immune system “interprets” objects it encounters so as to classify them into “self” and “non-self,” in the interest of attacking the “non-self” entities.

These interpretive schemes imply purposes: in the first case, to avoid toxins and find food, and in the second to destroy harmful invaders. Indeed, I find it hard to imagine how biologists could even identify something called an immune system without the idea of “that part of an organism that has the purpose of destroying foreign invaders.” And how in the world would ethologists begin to understand, or even to recognize as separate from all other wolf behaviour, the way a wolf pack coordinates its hunting activities, except by recognizing that these activities have the “purpose” of catching prey? Or consider the “bee dance.” It was a major breakthrough in understanding what was going on with this activity (which had been recognized as early as Aristotle) when Karl Von Frisch realized that this dance had the “purpose” of directing other bees to good sources of nectar.

Mario writes: “If a evolutionary biologist says something like ‘the animal’s long neck has the function of helping it get food from high trees,’ there is no implication that it might not also have another function.” Secondary functions of biological features no doubt exist. Indeed, as we have seen, Aquinas assigns to human sexuality three different functions. But does anyone really doubt that eyes evolved “in order to” yield to their bearers increased information about their environment from the electro-magnetic spectrum, even if, as a secondary feature, when I bat my baby blues all the ladies swoon? (Well, OK, perhaps only my wife swoons.)

I don’t regard any of the examples presented above as being anywhere near conclusive evidence that biological theorizing inherently incorporates the notion of purpose. Perhaps some ideal, future biological science will indeed do without teleology. But the fact that most biologists, for more than a century, have pledged their allegiance, at least when directly addressing the matter, to the scientistic goal of banishing teleological thinking from their theories, and yet biology is still suffused with such heretical explanations, to the extent that even a religious materialist such as Richard Dawkins cannot help but assigning to genes the “purpose” of replicating themselves, should at least make us give serious consideration to the idea that intentionality is a perfectly valid, perhaps indispensable, part of biological science.

15 Responses to “Can Biology Dispense with Purpose?”


  1. Jeff Shrager wrote an interesting paper in 2003 about the problems with assigning function in biology. He argued that we need to be careful to recognize that functions are only defined ‘dynamically’ in the context of particular explanations.

    see: http://bioinformatics.oxfordjournals.org/cgi/reprint/19/15/1934

  2. Ryan Says:

    I honestly don’t think that the issue you are dealing with is just a matter of biological science though. The human mind seems to naturally work by thinking teleologically.

    http://www.scientificamerican.com/article.cfm?id=creationism-feels-right-but-that-doesnt-make-it-so

    Because of this, I wouldn’t consider our teleological explanations proof of anything. I would imagine that when dealing with living things, it just is more natural to work teleologically, even if it had incorrect intuitions.

  3. Lee Kelly Says:

    Biology should be explaining purpose, not dispensing with it.

  4. Roger Koppl Says:

    I don’t think it is controversial today that animals have purposes. What is usually denied, I think, is that speciation is teleological.


  5. Adrian, Shrager’s paper seems to be more a puzzle over whether or not functions are only parts of explanations — and he wonders the same thing about objects. But if both functions and objects are features of explanations, then just what is being explained?!


  6. “The human mind seems to naturally work by thinking teleologically.”

    So, the fact that the human mind has evolved to think teleologically… is evidence that the teleology is NOT there?

  7. Mario Rizzo Says:

    Philosophers of biology (if there really are any) use the term “purposes” in a way likely to be misunderstood by many. It conveys the idea that human intentions, purposes are similar to those of animals. In some ways that would be accurate, but in others it would be quite inaccurate. I much prefer to follow the convention simply to call “intentionality” — when it comes to animals — *function*. The word purposes suggest a conscious end. (I know it does not have to but for my purposes here that possibility is important.)

    So it can be said of the animal with a long neck that, generally speaking, the neck has the function of helping it get food from high trees. Now we need not hypothesize that the animal is consciously using the neck for that purpose. Furthermore, we need not believe that the animal chooses to use it for that purpose or has the ability to choose to use it for another purpose.

    Now to man. A human being can choose to use his genitals to reproduce or not. Consider the celebate clergy. A person can use his hands to gather food or not if he should choose to fast or diet. Much of what we do with our time and bodies “mocks” evolution in ther sense that we override considerations of reproductive success at every turn. We do not reproduce to the extent possible (or at all); we extend our lives beyond the point of our reproductive years; we offer our reproductive energy to an invisible God, etc.

    So what is the “natural law” standard of whether or when we should override biological function (purpose) in the service of something else — perhaps a greater good? It would get complicated to answer this because we would then have to recognize (as many natural law philosophers do) other goods for mankind. And once they do that it becomes obvious, to me anyway, that there is no single hierarchy of goods for all people, especially in the particular circumstances of time and place that they find themselves. One natural law philosopher who recognized this very well is Yves Simon. He taught philosophy at the University of Chicago and Georgetown University.

  8. Greg Ransom Says:

    The idea that teleological explanations are going anywhere is ridiculous.

    Read Larry Wright’s _Teleological Explanation_ of the work on the philosophy of biology by Alexander Rosenberg.

    Rosenberg calls Wright’s work “the most important work on teleology since Aristotle”.

    And he’s right.

  9. Greg Ransom Says:

    Alexander Rosenberg has some great papers on the role of functional explanation (a variety of teleological explanation) and it’s non-reducibility in biological science. He also goes through his results in several books, all of which are worth reading.

    I’ve also written a paper “Insuperable Limits to Reduction in Biology” which combines the ideas of Larry Wright, Friedrich Hayek, Alex Rosenberg and David Hull, proving why teleological explanation in biology can never be fully reduced to physical or chemical explanations.

  10. David Hasbern Says:

    This is an interesting attempt to revive the notion of “teleological explanations.” As recently as 1993 Anthony Serafini argued in his class history of science textbook THE EPIC HISTORY OF BIOLOGY that teleological explanations may have some role in science so long as it doesn’t degenerate to our saying such things as ‘the acorn grows because it “wants” to become an oak tree

  11. Roger Koppl Says:

    Greg,

    Your paper sounds interesting. Where did it appear?

  12. Greg Ransom Says:

    Roger, You can find it here:

    http://hayekcenter.org/ransompapers/Limits_to_Reduction.html

    I never had time to bust it up and put it in a form for publication.

    Rosenberg seems to have been influenced by it’s core conclusion in some of his post 1992 work.

    Rosenberg, of course, couldn’t have wanted to swallow the paper’s anti-“received view” / anti- Hume-Mill-Nagel-Hempel / anti-“science” = physics thrust, an anti-received view position which owes much more to Wright and Hayek and Hanson and Wittgenstein, etc. than it does to Rosenberg. What you find Rosenberg doing is going “instrumentalist” and almost “eliminativist” about biological categories in his later work on reduction in biology.

  13. Greg Ransom Says:

    Compare my arguments here:

    http://hayekcenter.org/ransompapers/Limits_to_Reduction.html

    with Rosenberg’s arguments here:

    http://www.duke.edu/%7Ealexrose/how.pdf

  14. Greg Ransom Says:

    Note that functional individuation together with multiple realizability as a barrier to reduction was an idea already found in Hayek’s 1941-1943 essays “Scientism and the Science of Society” — which Hayek even then recognized as a reduction-blocking “many-many” problem (see David Hull on this problem in Darwinian biology). Hayek discusses the same sort of reduction blocking many-many problem in the domain of neuroscience/brain science in his _The Sensory Order_ (1952).

    Rosenberg in his paper linked above writes:

    “A recent discussion of how functional individuation together with multiple realizability obstructs the possibility of strict laws in biology, and the so-called “special sciences” is Lawrence Shapiro, “Multiple Realizability”, Journal of Philosophy. 97 (2000): 635-654.
    Shapiro’s treatment rehearses a well known literature which begins with J. Fodor, “Special Sciences”, in Representations Cambridge, Ma., MIT Press, 1981.”

  15. Greg Ransom Says:

    Compare some of the arguments in my “Irreducible Limits to Reduction in Biology” with some of Rosenberg’s arguments here:

    http://www.duke.edu/%7Ealexrose/how.pdf


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