Simplicity, one-shot hypotheses and paleobiological explanation

Paleobiologists (and other historical scientists) often provide simple narratives to explain complex, contingent episodes. These narratives are sometimes 'one-shot hypotheses' which are treated as being mutually exclusive with other possible explanations of the target episode, and are thus extended to accommodate as much about the episode as possible. I argue that a provisional preference for such hypotheses provides two kinds of productive scaffolding. First, they generate 'hypothetical difference-makers': one-shot hypotheses highlight and isolate empirically tractable dependencies between variables. Second, investigations of hypothetical difference-makers provision explanatory resources, the 'raw materials' for constructing more complex-and likely more adequate-explanations. Provisional preferences for simple, one-shot hypotheses in historical science, then, is defeasibly justified on indirect-strategic-grounds. My argument is made in reference to recent developments regarding the K-Pg extinction.