In this article, Dylan William states that the central claim in Baird, et al.'s piece is that if theories of assessment take into account theories of learning, assessments will somehow be more valid, and some of the more egregious effects of assessment on learning will be ameliorated. William responds to this claim by arguing that it seems plausible that assessments that indicate how far a student falls short of a desired level of performance in that domain would provide useful information about what might be done next. However, such a belief assumes that levels of performance in an assessment represent stages through which learners progress--a variant of Haeckel's idea that ontogeny recapitulates phylogeny (Haeckel, 1866). While this may often be true, William asserts, recent advances in cognitive psychology suggest that this is often not the case. The remainder of the commentary follows the structure used by Baird et al. (2017), beginning with some comments on previous work in this area, some reflections on the section on educational assessment, psychometrics, and learning, and an examination of the two case studies in the paper, international comparisons and assessment for learning. [This article is a commentary on Jo-Anne Baird, et al.'s "Assessment and Learning: Fields Apart" (EJ1149539).]