My aim in this contribution is to ask how both the findings and the limitations of social science should inform the debate on global economic justice among liberal political philosophers. I shall focus on the central place that this debate has allocated to political and economic aspects of natural resource wealth. Furthermore, I shall also try to provide a broader introduction to some key liberal discussions of global justice. In the process of pursuing this agenda, I will advance three main claims. First, I will show that social science research casts doubt on key premises of important liberal global justice theories. However, second, I will also suggest that empirical questions pivotal to these theories bring to the fore important limitations inherent to social science work on global issues. These limitations will lead me to argue, third, that new normative concerns should feature in liberal discussions about global justice. I commence my argument with introductory remarks concerning the liberal debate on global justice (section 1). I emphasize the debate’s enduring roots in John Rawls’ (1999) ideas, particularly concerning (1) the moral arbitrariness of natural endowments, and (2) the significance of the socio-economic structures that form the background of interactions among agents. I move to introduce social science into the discussion, first by asking how it can inform Rawlsian claims, initiated by Charles Beitz (1979), concerning the moral arbitrariness of societies’ natural resource endowments (section 2). I then ask a parallel question regarding Thomas Pogge’s (2002) extension of the Rawlsian concept of a “basic structure” to global politics (section 3). Both Beitz’s and Pogge’s arguments turn out to hinge on causal claims that currently lack social-scientific support, but that also seem extremely difficult to evaluate through social-scientific tools. I therefore end by asking (in section 4) what should be our normative position concerning global reforms that hinge on social-scientific confidence that we not only lack at present, but also seem unlikely to attain in the future.