Why are polar bears white? Although we can offer logical explanations to this question – such as ‘it provides a selective advantage when hunting seals’ – to do so is to play a teleological game of some kind. Teleology refers to the study of design and purpose in nature (or elsewhere). Before Darwin, teleology was the dominant explanatory mechanism in biology, explaining features in terms of why it was the best solution. Since Darwin, teleology has remained the dominant explanatory mechanism. All that has changed is the metaphysical justifications that are attached to these explanations.
This is a post about the philosophy of evolution. It expands upon a point raised in passing in Quid Pro Quo, which should be considered a pre-requisite for understanding this post. This in turn builds upon Popper’s Milestone, which is also required reading for full appreciation of the arguments being discussed here.
I feel it is necessary to provide some disclaimers before beginning. To anyone who objects to this discussion on the grounds that evolution is somehow in conflict with religious faith, I quote Theodosius Dobzhansky (an Orthodox Christian) who wrote in Nothing in Biology Makes Sense Except in the Light of Evolution:
Does the evolutionary doctrine clash with religious faith? It does not. It is a blunder to mistake the Holy Scriptures for elementary textbooks of astronomy, geology, biology, and anthropology. Only if symbols are construed to mean what they are not intended to mean can there arise imaginary, insoluble conflicts. ...the blunder leads to blasphemy: the Creator is accused of systematic deceitfulness.
And to anyone who mistakenly assumes that my criticisms in this post are meant to discredit evolution, I quote R.C. Lewontin from The Doctrine of DNA: Biology as Ideology:
No scientist doubts that the organisms on earth today have evolved over billions of years from organisms that were very unlike them and that nearly all types of organisms have long since gone extinct. Moreover, we know this to be a natural process resulting from the differential survivorship of different forms. In this sense, we all accept Darwinism as true.
But, much like R.C. Lewontin, I contend that accepting that there is something we can call the evolutionary process does not permit ideology (and hence metaphysics) to be considered a legitimate part of science, unless we choose not to enforce Popper’s milestone in which case even Intelligent Design cannot be excluded from science – a solution I hope to avoid.
Why is the Polar Bear White?
What is wrong with saying ‘the polar bear is white because it confers a selective advantage when they are hunting seals.’ The answer to this is simple: how would we test this claim? And if we cannot test it, we certainly cannot falsify its claim. As such, that places this particular statement in metaphysics and not in science.
It may help to clarify this situation if we consider some counter claims along similar lines. Consider, for instance, the scenario that at some point in the past the polar bear was hunted by a predator. In this scenario, we can claim the polar bear is white because of a selective advantage that helped them avoid predators. Also, consider the scenario that polar bear ancestors became white purely by chance, and then discovered that being white allowed them to hunt seals. The hunting of seals has become an effect when previously it was suggested as a cause!
Science does not advance by fabricating logical explanations and then accepting them because they sound reasonable – science expressly presumes that when we make a statement we can test and (to some extent) verify that claim experimentally. Claims that cannot be tested belong in metaphysics no matter how logical they sound.
Games of Teleology
Anyone can play a teleological game – and it’s fun to do so! Simply look at some animal and devise an explanation for its features or behaviour in terms of some explanatory scenario. Those that do not wish to use evolution may do so by playing a teleological game with God as the explanatory factor; those that would rather play sans Deus might prefer to use ‘selective advantages’ or something similar. The game will play quite similarly either way.
An ovate or oblong form is consequently the very best that could be adopted; and, moreover, the points with which it is covered and adorned, are evidently designed to protect the shell from external injury… At the same time a beautiful variety of tints evince that minute attention to the finishing and decorating of his works which the Deity so continually displays.
- The Conchologists Companion, Mary Roberts 1834 AD
Mary plays her teleological game with God, claiming that animals display the best form that could be adopted because of the care and attention of God.
Many citrus trees that are natives of arid regions have sour fruit to discourage animals from eating it. The flesh of a lemon is there for three main reasons: to add weight so it will roll a long way after it falls from the tree, to dissuade foraging animals from eating the seeds before they can develop, and to supply water and nutrients as the flesh rots around the germinating seeds. The main aim of any seed is to propagate the species, not to feed the local animals.
- Letter to ‘New Scientist’, Joanna Burgess, April 1999 AD
Joanna plays her teleological game with the gene-centric view. She devises an explanation for sour fruit on the assumption that “the main aim of any seed is to propagate the species”. But this is an odd claim! Because what does it mean to suggest that a seed has ‘a main aim’? She is proceeding from the assumption that the meaning or purpose of life is to propagate itself. But this is surely metaphysics, for any discussion of ‘meaning’ or ‘purpose’ must necessarily fall within this domain. This is why Einstein stated:
What is the meaning of human life, or of organic life altogether? To answer this question at all implies a religion.
(I would say it implies metaphysics, but we have already seen the argument that metaphysics is the domain of religion, not of science).
It is certainly logical to suggest that fruits in arid regions are sour because it was a selective advantage to discourage animals to eat them, thus keeping their water to themselves. Elsewhere, where water is more common, having tasty fruit that animals will eat thus spreading seeds over a wider area can be seen as a selective advantage. But does this really make sense? Are we suggesting that once upon a time all the fruits were tasty, but the desert fruits adapted to being sour? What if once upon a time all the fruits were sour, but the temperate fruits adapted to be tasty to gain the opposite advantage? There are so many possible stories we can tell, and few if any of them are testable.
The Game of Evolution
The problem occurs in part because of the assumption that evolution is purely a game of agon: species compete with each other for resources and the “fittest” (i.e. the best adapted to its environment) survives. But even if this assumption were true, the lineage of any given species spreads over millions (even billions) of years and we have only the utterly incomplete fossil record to provide clues as to what was a selective advantage at any given time. We cannot know which traits provided specific selective advantages, because we cannot see through time, and nothing in our evolutionary theories allows for us to predict that all observable traits provided an advantage at all times, or indeed at any given time.
Stephen J. Gould raised the quite legitimate point that we cannot know which traits of an organism are the results of selective advantages, and which are simply artefacts of the evolutionary process. His research had focussed on extinction by lottery, and as such it was clear to him that chance played as big a role in the history of life as competition – or to put it another way, that evolution was a game of alea as well as a game of agon. Furthermore, R.C. Lewontin noted that the usual process in biology of looking for the cause of an effect – presuming that there is such a thing as a major cause, and that all other factors can effectively be ignored – was a terribly naïve way of looking at biological systems which contain many intricately interrelated elements, and do not lend themselves to analysis through an overly simplistic model of causation.
Popper retracted his claim that Darwinism a metaphysical research program and not a testable scientific theory because he was shown evidence of biologists using optimization analysis to make predictions about changes in the statistical distributions of characteristics in real animal populations. But while the capacity to make testable assertions about future populations constitutes a scientific validation of Darwin’s theory, it categorically does not mean that teleological games played using Darwin’s theory (or something similar) are any more scientifically valid than those same games played with God. The validation of the theoretical framework is an entirely separate issue from the widespread practice of making metaphysical statements and presenting them as if they were science.
We have several sources of data from which to form scientific theories about the past. The fossil record provides evidence spanning billions of years, although it is incomplete, and its interpretation can be highly subjective (as clearly indicated by the case of the Burgess Shale). The geological record is more complete, but also more general. The genetic transcript provides some information, especially about events less than a million years ago (such as historical human migrations), but does not allow us to see very far. Radiocarbon dating is another source of data, but only about the ages of things. It is likely we will acquire some new techniques over time, but it is highly probable that we will always be interpreting the past with a mere sliver of data, at least compared with the wealth of options we have for the scientific investigation of other areas.
In the sense of identifying a single causal factor, we may never be able to say with any scientific confidence “why the polar bear is white”, although we may conjecture to our heart’s content! We are free to play our teleological games however we wish, but we should not present them as if they were science. When we make statements which lack a framework whereby they might be tested and falsified, we are blurring the boundaries between metaphysics and science. It is the confusion of these boundaries that opens the door to metaphysical models such as Intelligent Design, and anyone who wishes to keep ID out of science should therefore strive to ensure that their own scientific writing is free of metaphysical elements such as teleological games.