 It was noted earlier that if what counts as selection is non-arbitrary, then it cannot be the case that what is quantified by the \(w\)’s in type recursions and the covariance of offspring number and phenotype both count as selection. A substantial debate has arisen over the question of whether what counts as selection is indeed non-arbitrary. In particular, some philosophers dubbing themselves “statisticalists” have challenged the non-arbitrary character of the distinction, claiming that it is model-relative (Walsh, Lewens, &amp; Ariew 2002; Walsh 2004, 2007; Walsh, Ariew, &amp; Matthen 2017). (For more on the arbitrariness of the selection/drift distinction, see entry on  genetic drift).  A related issue, discussed in the subsequent section, concerns the causal interpretability of the theory: Advocates of the non-arbitrary character of selection also typically treat selection and drift not only as non-arbitrary quantities, but also as causes, while those who allege that the distinction is arbitrary typically equally challenge the treatment of selection and drift as causes. 