Stephen L. Talbott tackles the tautology question over at The New Atlantis:
Along with his anecdote about the wolf, Bethell argued that evolutionary theory based on natural selection (survival of the fittest) is vacuous: it states that, first, evolution can be explained by the fact that, on the whole, only the fitter organisms survive and achieve reproductive success; and second, what makes an organism fit is the fact that it survives and successfully reproduces. This is the long-running and much-debated claim that natural selection, as an explanation of the evolutionary origin of species, is tautological — it cannot be falsified because it attempts no real explanation. It tells us: the kinds of organisms that survive and reproduce are the kinds of organisms that survive and reproduce.
It happens that Bethell was savaged by Stephen Jay Gould in 1976 for making this claim. Gould pointed out that Darwin and his successors hypothesized independent conditions — “engineering criteria,” as biologists like to say — for the assessment of fitness. These conditions may facilitate and explain reproductive success, but do not merely equate to it. In other words, the concept of fitness need not rely only on the concept of survival (or reproductive success).
However, the appeal to engineering criteria in the abstract does not by itself get us very far. As philosopher Ronald Brady reminded us when discussing this dispute in an essay entitled “Dogma and Doubt,” what matters for judging a proposed scientific explanation is not only the specification of non-tautological criteria for testing it, but also our ability to apply the test meaningfully. If we have no practical way to sum up and assess the fitness or adaptive value of the traits of an organism apart from measurements of survival rates (evolutionary success), then on what basis can we use the idea of survival of the fittest (natural selection) to explain evolutionary success — as opposed to using it merely as a blank check for freely inventing explanations of the sort commonly derided as “just-so stories.”
Some philosophers and evolutionary biologists have long referred with a note of patronizing scorn to anyone who brings up the “tautology problem,” as if the reference betrays hopeless ignorance of a problem long ago solved. For example, Michael Ruse, reviewing a book by Philip Kitcher, could already refer in 1984 to the “hoary old chestnut” about tautology, and then (in sympathy with Kitcher) dismiss the claim as “ridiculous.” After all, he writes, “Could generations of evolutionists really have been deceived into thinking they were doing empirical studies, when they spent hours crouched over fruit-flies in the lab, or weeks tramping through the woods looking at butterflies, snails, and finches? A tautology requires no such study.”
But what is really ridiculous is to suggest that empirical work, simply by virtue of being empirical work, offers a proper test of any particular theory. Certainly the work of evolutionary biologists has brought us many wonderful insights into the lives of organisms — insights of the sort that were being gained long before Darwin. But such insights provide a test of the theory that the origin of species can be adequately explained by natural selection of the fittest organisms only if they do in fact provide a test. Simply refusing to address the question does no one any good. (The dismissive attitude exemplified by Ruse continues into our own day. As a response to it, Brady’s essays remain relevant and illuminating.)