The assumptions that are made about the features of the world that are relatively changeable by agents and those that are not (constraints) play a central role in determining normative conclusions. In this way, normative reasoning is deeply dependent on accounts of the empirical world. Successful normative reasoning must avoid the naturalization of constraints and seek to attribute correctly to agents what is and is not in their power to change. Recent discourse on global justice has often come to unjustified conclusions about agents obligations due to a narrow view of what is changeable and by whom.