In North America the black bear was seen by Hearne swimming for hours with widely open mouth, thus catching, like a whale, insects in the water. Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.Darwin deleted this from later editions. Modern cladistics places the whale as being most closely related to the hippopotamus.
Wade’s explanations commit various well-known errors, such as equating correlation with causation and extrapolating from individual traits to group characteristics….The book has many internal inconsistencies, and one can easily find contrary evidence or readily construct alternative ‘just so’ stories that invoke the same genetic scenario and the same kind of reasoning.
Flanagan does give a just-so story about how consciousness could have evolved through natural selection, but just-so stories run counter to his very simple methodological suggestion --- use all the information one can get from any science that seems relevant to the task at hand; otherwise, wait until the data is available. Just-so stories aren't very scientific. Indeed, as long as we are allowed to spin arm-chair theories, why not consider consciousness to be a phenotypic free-rider, like the chin, such that no Darwinian story is going to explain its purpose, since it does not have one.
For example, in cosmology, string theory as yet has no empirical evidence to support it. Yet it is seen by many cosmologists as mathematically plausible, and it may be empirically falsifiable in the future given new research tools.
Critics of evolutionary psychology have sometimes used the term "just so story" as a derogatory way of describing alternative hypotheses which need empirical evaluation, but which are plausible and are taken seriously by knowledgeable experts. Leda Cosmides noted in an interview:
Those who have a professional knowledge of evolutionary biology know that it is not possible to cook up after the fact explanations of just any trait. There are important constraints on evolutionary explanation. More to the point, every decent evolutionary explanation has testable predictions about the design of the trait. For example, the hypothesis that pregnancy sickness is a byproduct of prenatal hormones predicts different patterns of food aversions than the hypothesis that it is an adaptation that evolved to protect the fetus from pathogens and plant toxins in food at the point in embryogenesis when the fetus is most vulnerable – during the first trimester. Evolutionary hypotheses – whether generated to discover a new trait or to explain one that is already known – carry predictions about the nature of that trait. The alternative – having no hypothesis about adaptive function – carries no predictions whatsoever. So which is the more constrained and sober scientific approach?
Further, some hypotheses that have been labeled as "just so stories" by misinformed critics do indeed have some empirical support. See Controversies surrounding evolutionary psychology by Edward H. Hagen, and books by Segerstråle (2000) and Alcock (2001).
The generation of plausible hypotheses is one part of theory creation and evaluation in normal science.
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