 There exists very little discussion of formal models in statisticalist writings; various toy scenarios are put forward instead, and these are not analyzed using the techniques of formal population genetics (Matthen &amp; Ariew 2002; Walsh, Lewens, &amp; Ariew 2002; Walsh 2007; Walsh, Ariew, &amp; Matthen 2017). When biologically realistic scenarios are discussed, systems of equations for inferring how such systems behave are not made part of the discussion (for more on population genetics, see entry on  population genetics).  We consider next a case they discuss because it provides a way of contrasting how the contrast between selection and drift is made in type recursions and how it is made in the Price Equation. There is a sort of arbitrariness here, but it emerges only from analysis of a hypothetical system using population genetics modeling techniques.