 One issue that remains under-explored, philosophically, is how the distinction between passive vs. driven larger-scale trends might intersect with philosophical disagreements about whether neo-Darwinian evolutionary theory is best understood as a causal theory (a view given its canonical formulation by Sober 1984) or a statistical theory (Matthen and Ariew 2002; Walsh, Lewens, and Ariew 2002). There may be some question about whether it is best to understand the passive/driven distinction as a distinction between trends generated by different causal mechanisms, vs. a distinction between different sorts of statistical phenomena.