 Accounts can be given at several levels to explain the correctness of shì/fēi 是非 judgments. Most immediately, shì/fēi distinctions seem to rest on social norms for distinguishing various kinds of things. This view is suggested by how the Mohists describe the process by which we learn to judge shì and fēi: through conformity to the model set by social superiors. According to the theory of the  “three models,”  these norms for drawing distinctions rest in turn on three fundamental standards: the precedent set by wise leaders of the past, perceptual experience, and benefit to society. To some extent, then, the norms have a real basis in perceptual experience and in whatever strategies actually work, in practice, to promote “benefit,” which the early Mohists understood as wealth, population, and social order. The Mohists also seem to have thought they could ground at least some of these norms—specifically, ethical norms—in the patterns of action exemplified by tiān 天 (Heaven, nature) itself. The third of the “three models” is also grounded in the norms that tiān follows, specifically the norm of promoting benefit to all. So shì/fēi distinctions based on benefit are also, at least in an indirect sense, underwritten by tiān. 