 As noted earlier, theorists working on type recursions who defend the view that selection is a distinct quantity from drift typically defend the view that it is also a distinct cause. Forber and Reisman explicitly invoke the interventionist account of causation and argue that natural selection (and drift) qualify as causes (Reisman &amp; Forber 2005). They do so on the basis of an examination of experimental work in which selection (and drift) are manipulated to produce changes in population-level behavior. “Causalists” working with type recursions must confront the natural philosophical challenge of stating, precisely, what cause or causes count as selection, that is, what exactly fitness coefficients quantify. The Beatty/Millstein interpretation of selection as discriminate sampling is explicitly causal. Equally, Otsuka’s position that fitness coefficients should be interpreted as linear path coefficients from phenotype to offspring number in causal graphs is clearly causal as well.