A long time ago I wrote a not particularly good piece on the tautology problem: that natural selection is merely circular definition. I was just out of being an undergraduate when it was published, so it was at best an undergraduate piece. I have been unsatisfied with it ever since. So I will from time to time post on this. To start, what’s the history?
You may have thought – I did – that this would be a criticism of Darwin from the start: that survival of the fittest is an empty tautology. But in fact it doesn’t seem to have started until the centenary of the publication of the theory of evolution in 1958, which is when a number of mythologies about Darwin seem to have originated. I wonder if this is because there really isn’t anything as revolutionary individually about Darwin’s ideas, when the totality is itself a revolution? The fallacy of division may be to blame; we want Darwin to be revolutionary in all his parts as well as overall. Anyway, that’s for another post.
At least one source suggested it began with the Bishop of Carlisle in the 1890s, but when I tracked him down, he in fact merely said that natural selection was not creative, but merely filtered out disadvantageous variants:
I am not going to make any objection to Mr. Darwin’s ingenious theories with regard to natural selection, the survival of the fittest, and selection in relation to sex; but I wish to impress upon you this point, namely, that there is in all these theories no real machinery (so to speak) for the improvement or change of species or races: supposing that you have got your improvement there is a reason assigned why it should become permanent, but no reason is assigned why it should in the first instance occur1.
1. See Mozley’s Essays, vol. ii, p. 396. “Natural selection is not an agent, but a result. . . . Natural selection only weeds, and does not plant; it is the drain of Nature carrying off the irregularities, the monstrosities, the abortions ; it comes in after and upon the active development of Nature to prune and thin them ; but it does not create a species; it does not possess one productive or generative function.”
. . . You will, of course, observe that in what has now been said I am by no means denying the possibility, or even the probability, of evolution of higher forms of life from lower: I have already agreed to grant all that may be asked in this direction: what I insist upon is that the survival and perpetuation of a higher form of life, when it has appeared, affords no explanation whatever of the fact that it did appear. [Goodwin 1880, p31, 33]
The logical nature of Darwin’s theory was in fact mentioned by none other than C. S. Peirce:
The Darwinian controversy is, in large part, a question of logic. Mr. Darwin proposed to apply the statistical method to biology. The same thing had been done in a widely different branch of science, the theory of gases. Though unable to say what the movements of any particular molecule of gas would be on a certain hypothesis regarding the constitution of this class of bodies, Clausius and Maxwell were yet able, by the application of the doctrine of probabilities, to predict that in the long run such and such a proportion of the molecules would, under given circumstances, acquire such and such velocities; that there would take place, every second, such and such a number of collisions, etc.; and from these propositions were able to deduce certain properties of gases, especially in regard to their heat-relations. In like manner, Darwin, while unable to say what the operation of variation and natural selection in any individual case will be, demonstrates that in the long run they will adapt animals to their circumstances. Whether or not existing animal forms are due to such action, or what position the theory ought to take, forms the subject of a discussion in which questions of fact and questions of logic are curiously interlaced. [Peirce 1877]
Clearly this is not a criticism. In fact, by making the analogy with the statistical theory of gases, Peirce is making a rather deep point, one I hope to return to later. The deep point is that a general, mathematical, explanation is one that the best science aspires to. Darwin’s theory of natural selection is a logical theory, yes, but it relies on questions of fact.
The first apparent statement of the tautology claim was in 1958, as I said, and it was not a criticism of natural selection:
These [struggle for existence, survival of the fittest] emotionally loaded phrases have been often misused for political propaganda purposes. A less spectacular but more accurate statement is that carriers of different genotypes transmit their genes to the succeeding generations at different rates… The “fittest” is nothing more remarkable than the producer of the greatest number of children and grandchildren. [Sinnott, Dunn and Dobzhansky 1958, pp. 100-101]
To head off the political misuse of natural selection, these leading authors point out that the principle of natural selection is merely a definition. “Fit” does not have any deeper meaning than “number of descendants”, so Nazi and other forms of political evolutionism are simply mistaken in their view of what matters. A nice side effect of this is that if the Nazis are right that the “subhumans” are outbreeding the “Aryans”, then the “subhumans” are more fit! Deal with it.
But, as Diane Paul went on to say, “Thus was born the famous “tautology problem”, which has bedeviled the field ever since” [Paul 1992, p114].
At first, this was not terribly concerning to anyone. The mathematics of evolution, developed as population genetics, simply posited a variable w for fitness. Individual organisms had a w, populations had an average w, and genes – alleles – had a w, which was basically the statistical number of copies after some number of generations (usually three, the F2 generation or second daughter generation).
Then, a philosopher, Michael Lerner, wrote this for the centennial of the Origin:
Thus, although Darwin may have erroneously accepted the view that survival is necessarily the major component of natural selection, he understood that the crux of the selection process lies not merely in the ability of an individual to survive longer than others, but in its greater capacity for production of living offspring; that is to say, not only in survival of individuals within a generation, but of groups over a period of generations.
This fact enables us to answer the third question, that regarding the interpretation which must be given the word fittest, or rather, the term fitness. The expressiveness of Spencer’s superlative seduced Darwin into accepting “survival of the fittest” as being equivalent to “natural selection.” As a result, many early evolutionists and a fair proportion of those naturalists of today whom the literature of population genetics has bypassed attached anthropomorphic value judgments to selection. Yet neither strength of character nor moral goodness, neither extreme size nor high intelligence, nor even long life per se causes an individual to produce more offspring, that is to say, make it fit in Darwin’s sense. Indeed, often organisms which are totally undistinguished by any physical standards, organisms exhibiting average dimensions for various properties, in fine, individuals which are mediocre for any traits obvious to the human eye, are the ones that are most successful in propagating themselves. They are therefore the fittest. If there is one thing upon which the most factious partisans of various currents of evolutionary thought agree, it is that fitness of an individual, in the context of the natural selection principle, can mean only the extent to which the organism is represented by descendants in succeeding generations. Fitness can be discussed in absolute terms or expressed relatively to the average of a group. Immediate or more remote generations of descent may be chosen as a point of reference. Enumeration of offspring or some other way of assessing the “amount” of progeny left may be resorted to. But in all instances, fitness must refer to the ability of an organism to leave surviving offspring.
A habitual fallacy, shared by both the opponents and the supporters of evolution by natural selection, is the idea that any part of evolution may be explained by saying that the fittest individuals have the most offspring. When fitness is considered with reference to evolutionary phenomena, such statement is logically circular and begs the question. If capacity of reproduction is the criterion of fitness, the only connecting proposition between reproduction and fitness which avoids tautology is that individuals having most offspring are the fittest ones. This is neither an assumption, nor a hypothesis to be proven, but merely a definition. [Lerner 1959]
Even here, this is about the term “fitness”, as a term in the theory. It’s just a variable that is used in the calculation. Again, Lerner is striving to avoid the moral value of the term “fit” (the term “fitness” itself appears to have arisen sometime in the 1930s, possibly by Wright.* Fisher in 1930 used the term “reproductive value” in analogy to an economic theory, to underpin his positive eugenics) that was used by the Nazis and other “social Darwinians” that those who strive hardest in some morally laudable manner are those whom evolution favours. But now, we have to deal with the apparent lack of explicability of the theory of natural selection. How can it explain when the key property – fitness – is merely defined? [It did not escape the attention of people that this is also true of Newton’s term g for gravity in classical mechanics.]And then, in a book that instituted the modern version (the third generation) of neo-Darwinism, George C. Williams wrote:
Like the theory of genic selection, the theory of group selection is logically a tautology, and there can be no sane doubt about the reality of the process. Rational criticism must center on the importance of the process and on its adequacy in explaining the phenomena attributed to it. [Williams 1966, p109]
Here it is most clearly – natural selection is a logical a priori truth. What we must now argue over is how important it is. As Shaw once said, we know what we are, now we are haggling over the price.In the next post I will discuss how this became a philosophical, and later a creationist, problem for evolution, leading to it being the single greatest problem in the philosophy of biology in the 70s and 80s. Then, we shall consider the various arguments that go by this name, and after that I will make a positive argument of my own.
* Wikipedia says it was J. B. S. Haldane’s 1924 paper, but while he has a term un that he determines the rate of change ?un. This he terms the proportion of alleles in a nth generation. Later: I found it in Fisher’s book after all, on page 37, which he terms as m, “the objective fact of representation in future generations”. It’s in his fundamental theorem. How did I miss that?
Later note: See the correction that follows.
Fisher, Ronald Aylmer. 1930. The genetical theory of natural selection. Oxford UK: Clarendon Press, (rev. ed. Dover, New York, 1958).
Harvey Goodwin, Lord Bishop of Carlisle. 1880. The origin of the world according to revelation and science: A lecture. London: The Christian Evidence Committee of the Society for Promoting Christian Knowledge.
Haldane, J. B. S. 1924. A mathematical theory of natural and artificial selection. Transactions of the Cambridge Philosophical Society 23:19-41.
Lerner, I. Michael. 1959. The Concept of Natural Selection: A Centennial View. Proceedings of the American Philosophical Society 103 (2):173-182.
Paul, Diane. 1992. “Fitness” in Keller, Evelyn Fox, and Elisabeth A Lloyd, eds. Keywords in evolutionary biology. Cambridge MA: Harvard University Press, pp. 112-14.
Peirce, Charles Sanders. 1877. The Fixation of Belief. Popular Science Monthly 12 (November):1-15.
Sinnott, Edmund Ware, L. C. Dunn, and Theodosius Dobzhansky. 1958. Principles of genetics. 5th ed, McGraw-Hill publications in the botanical sciences. New York: McGraw-Hill
Williams, George C. 1966. Adaptation and natural selection: A critique of some current evolutionary thought. Princeton NJ: Princeton University Press