This paper explores the underlying framework of Kongzi’s 孔子 moral philosophy, and attempts to elucidate the role and importance of cosmology in understanding Kongzi’s moral teaching. Moral judgment concerns some criteria on which one can tell right from wrong, and this paper argues that Tian 天 as a cosmological entity provides a basis of ethical judgment for Kongzi’s ethical system. It is worth noting that within any given tradition, even seemingly distinct aspects or social institutions may be better understood if approached from a broad and holistic perspective. Applying this understanding to the comparative study of ethical traditions, this paper argues that ethical traditions tend to reflect and support the prevailing cosmological framework held by the individuals in that tradition. In this regard, it is articulated that Tian-based cosmology functions as one of the deciding criteria in Kongzi’s moral teaching and plays as an ultimate warrant for moral authority. One noteworthy feature of ethical teachings derived from Tian-based cosmology is that these rules are typically advanced and advocated as the manifestations of some type of “natural law.” Kongzi, for instance, claimed that his ethical teachings conform to the rules of Tian, an entity described as essentially naturalistic rather than anthropomorphic.