Dinosaur In a Haystack - A Website About Stephen Jay Gould's ...

counterproductive (due to their speculative and untestable assumptions). Gradualprocesses – to include the occasional earthquake, volcano, and flood, at the levelsobserved in historic times – should be exclusively assumed, he argued. The communityshould cease further theorizing, and instead concentrate on characterizing, dating, andmatching up the earth’s strata (a huge and vitally important undertaking, to be sure).Darwin strongly agreed with Lyell’s gradualist view of both geology and paleontology,but differed with regard to the philosophical perspective of pure observation with noconceptual, theoretical framework in mind. Gould’s office door displayed his “bumpersticker” view of the relationship of theory and observation, taken from the last sentenceof the following paragraph that Darwin wrote to Henry Fawcett in a letter from 1861:About thirty years ago there was much talk that geologists ought only to observeand not theorize; and I well remember someone saying that at this rate a manmight as well go into a gravel-pit and count the pebbles and describe the colors.How odd it is that anyone should not see that all observation must be for oragainst some view if it is to be of any service!In this passage, Darwin argues that it is essential to possess some sort of theoreticalframework if one is to organize and “make sense of” the observations one makes. Gouldextends this by claiming that it is impossible for humans not to hold or form at least atentative model while studying a subject. However, he adds, these models can also limitwhat we observe, constraining us as well as assisting us. There exists a myth aboutscience, he continues, that says practitioners modify or abandon their theories whenconfronted with data that refutes it. But this is not always true in practice. He writes:We say, in our mythology, that old theories die when new observations derailthem. But too often – I would say usually – theories act as straitjackets to channelobservations toward their support and to forestall potentially refuting data. Suchtheories cannot be rejected from within, for we will not conceptualize thedisproving observations . . . . We escape by importing a new theory and bymaking the different kinds of observations that any novel outlook must suggest.That is, he argues, new data by itself cannot overthrow an established theory. It can onlybe replaced when challenged by a different theory, one that makes different predictions.It is only in the context of two testable theories, he states, that we gain sufficientperspective from the results of our observations to modify or reject one of them. [Gouldis very partial to this argument; he used it in his first paper on punctuated equilibrium,where he argued that the paradigm of phyletic gradualism prevented scientists fromrecognizing the phenomenon of stasis, even though many “observed” it.] Importantly, anew theory – even if it fails – often suggests new lines of research that can lead tounexpected findings.By the time Gould wrote this essay in 1992, most members of the professionalcommunity had been convinced that a large impact did occur at the end of theCretaceous. [A few continued to argue that the source of the iridium in the clay layer wasvolcanic in origin.] Doubt and debate remained, however, as to whether the impact16