The correlation of ethics and economics in the neoclassical orthodox school has always been a problem. Using concepts of utility and preferences, the proponents of this school attempted to correlate morality and economics within the context of the welfare economy. Due to the essential ambiguity of the meaning of utility within the individualistic methodology of neoclassical economics, this correlation does not meet a desirable end; because by aggregating individual choices one cannot achieve a social choice in the welfare economics. Using an analytical approach, this paper studies the possibility of applying Allameh Tabatabai's conventions (i’ tibariat) theory to establish a correlation between ethics and economics. According to the research findings, this theory can make a correlation between moral and economic values. In this context, utility is considered as a social convention. Given the interpersonal nature of conventions, desirability will be sufficiently objective to serve as the link between moral and economic values. Thus, Allameh Tabatabai's theory of conventions provides a reasonable link between ethics and economics. This approach can also be considered as the beginning of a methodological study in Islamic economics based on Allameh's theories.