TESTING ADAPTATIONISM: A COMMENT ON ORZACK AND SOBER
One of the most heated areas of controversy within contemporary evolutionary biology concerns adaptationism and the importance of natural selection relative to other evolutionary factors. Because these debates sometimes seem to be more ideological than scientific, Orzack and Sober's (1994) recent suggestion about how to test adaptationism is likely to be well received. However, as we will show, both their statement of the hypothesis of adaptationism and their method of testing it are seriously flawed. We will try to refine the relevant hypotheses and consider the extent to which, and the methods by which, they can be tested. In this way we do take Orzack and Sober's project seriously. But, we wish to state at the outset that the status of the "adaptationist program" does not stand or fall on the outcome of their project or our revision of it here. That is, even if the hypothesis of adaptationism cannot be stated in a precise enough manner to be testable, or if it is so statable but proves to be false, the value of an adaptational approach to evolutionary biology is not necessarily diminished (see Mayr 1983 and Williams 1992 for further discussion). Nonetheless, we think it uncontroversial that in science a well-posed thesis is preferable, everything else being equal, to an ill-posed or untestable one, and our purpose here is to demonstrate that Orzack and Sober's thesis of what constitutes adaptationism is ill posed.