For Martha C. Nussbaum, the history of political philosophy possesses philosophical value for reasons that are seldom explicitly argued. It is not so much that past political philosophers are worthy of our attention primarily because they identified philosophical problems that we continue to consider significant. Rather, we should pay especially close attention to those who also managed to arrive at solutions to these problems similar to our own. Their significance for us stems less from the fact that we recognize their purported philosophical problems as our own problems and more from the fact that we sometimes discover their purported solutions to these problems mirroring or overlapping with our own. Consensus with the dead warrants philosophical claims as much as consensus with the living. For Nussbaum, discovering that T. H. Green’s philosophical liberalism emulates her version of the capability approach warrants its credibility. Intellectual history is sometimes philosophically very useful. The hermeneutical conundrums raised by this manipulation of intellectual history are considerable.

This essay seeks to get beyond the narrow debate between two candidate grounds for indexing advantage in accounts of justice: the Rawlsian primary goods of income and wealth and capability or capabilities. Rawls is more deeply committed to multidimensionality than this debate has tended to recognize. Commitment to multidimensionality is shallow if each of the multiple dimensions is seen as contributory to something sought only for its own sake that can be adequately represented along a single dimension, such as welfare or well-being as they are sometimes conceived. To avoid treating multidimensionality shallowly — whether within the domain of justice or outside it — defenders of appealing to capabilities would do well to follow Rawls in recognizing a division of moral labour among multiple principles, with the different principles serving different social values and addressing different sets of social institutions. This approach offers an attractive and flexible alternative to single-principle outcome-ranking approaches. Along the way, in reference to the older debates, it is shown that there is, for Rawls, no single currency of justice and that he has serious reasons, grounded in respect for the fact of pluralism, to avoid resting too much theoretical weight on the idea of well-being.

Nussbaum’s capabilities approach harks back to ancient Greek phūsis at the origin of the philosophical tradition, but it is a form of environmental humanism developing Enlightenment values. This complexity is not without its tensions. Using the contradictions I find contained in Nussbaum’s commitment to wonder as a universally important ethical experience, I push her extension of moral regard for other species farther than it can currently go. Nussbaum has transformed the Enlightenment concept of dignity to include other forms of life. Her considered position is a form of biocentric individualism. Biocentric individualism is the view that individual lives as such have dignity. However, I will show that her outlook, grounded in wonder, presents insurmountable obstacles to her biocentric individualism. I resolve these by suggesting that moral individualism ought to be jettisoned when species are not morally individualized in their form of life. I motivate this argument through the risk of a mass extinction cascade, which characterizes our planetary ecological situation and poses a threat both to human development and the moral and ethical commitments of the capabilities approach. I propose one general criterion for reasonable institutions regarding this risk, surrounding it with a call for environmental humanism in political culture.