Both contemporary popular and scholarly discourse on teacher development and evaluation assumes the truth of a certain view of normative human behavior, one that holds that skill in a given domain is predicated upon the application of maxims, rules, or principles in a given situation. Such a view would allow one to isolate behaviors associated with expert practice, distill the rules that give rise to them, and both develop new teachers and evaluate practicing teachers on the basis of such maxims. In this essay, Derek Gottlieb argues that the phenomenon of skillful teaching, and studies thereof, expose the inconsistencies and confusion underlying this model, encouraging the field generally to consider alternative holistic accounts of expert teacher practice as we seek to train and appraise great teachers. (Contains 31 footnotes.)