Social justice raises especially acute difficulties. What is fair distribution of social goods? Should distribution be based, as Marx suggested, on need; or on the basis of contribution by work and service, or effort, or some other index? Should governments aim to distribute goods equally, heedless of recipients’ needs, or aim for social equality, or withdraw and surrender justice to the regulation of the market? These are common questions, but to answer them adequately requires uncommon probing into the principles that define and support a just dispensation.

Such an investigation is the subject of another fine, learned, innovative but prolix book by the distinguished and prolific American philosopher Martha C. Nussbaum. Frontiers of Justice is informed by many elements of her previous work in social philosophy, and forms part of an impressive systematic progression. Like her previous books, it is a product of immense industry, wide-ranging sympathies and steady, unrelenting argument. Here she develops further an original account of justice, the ‘capabilities approach’. She does so almost exclusively against the backdrop of ‘social contract’ theories of justice, particularly that of the influential American philosopher John Rawls. The result is an intense but somewhat lopsided work.

The neglect of theories from other quarters is partly explained by Nussbaum’s repeated affirmation that the strongest approach to social justice in the Western tradition is based on the idea of the ‘social contract’. Hobbes, Locke, Rousseau in his different way, and Hume as a contributing outsider, are the major progenitors. In 1971, Rawls published A Theory of Justice, in which Kantian moral conceptions about individual inviolability were fused with an ingenious reconstruction of the social contract idea. The book had an immense influence in reviving normative moral and political thought, and it stands at the centre of Nussbaum’s investigations.

Briefly, the idea of the social contract is this. We are to imagine a state of nature, a stage of pre-political life, devoid of the benefits of social cooperation, in which men of roughly equal power war over scarce resources. In such a state, as Hobbes deathlessly put it, there is ‘continuall feare and danger of violent death; And the life of man, solitary, poore, nasty, brutish, and short’. To escape this condition, men will compact, but only, the story goes, in circumstances in which they expect to gain from it. This leads to a picture of society as a scheme of cooperation for mutual advantage. In Rawls’s refinement of the initial position, the contracting parties are imagined to be behind a Veil of Ignorance where they lack knowledge of their own particulars: status, class, wealth etc. Then, being self-interested but risk-aversive, the parties would choose a dispensation in which there is maximum liberty, compatible with liberty for others, and wealth is distributed so as to make the worst off as well-off as possible. The principles of justice are, in Rawls’s words, ‘the principles that free and rational persons concerned to further their own interests would accept in an initial position of equality’.

This picture of society as sustained by a contract for mutual advantage is a powerful one. It is, of course, a kind of fiction or model, but it shapes the perceptions we have of each other and of our place in society, and it provides bedrock for economic and political theorising. It at once evokes thoughts of ‘mutual obligation’, of everyone contributing and paying their way. It appeals to the hard-nosed theorist because only egoistic motives are required to make the model tick. The classical theorists and some of their descendants do not deny that there are benevolent motives in humankind; they just don’t believe that these are necessary, or potent enough, to bind people to a contract: only self-advantage is sufficient motive to participate in a just society. Nussbaum assails this picture. She scrupulously examines a number of prominent contract theories, providing much illuminating historical detail. With Rawls, Nussbaum has a protracted and repetitious conversation: she inclines, as was said of William James, to be ‘viciously fair-minded’. The contract theories have many difficulties, but they falter most conspicuously at the three frontiers of justice that focus her book: the decent treatment of the disabled, the elderly and children; just relations between nations; and the just treatment of animals.

There are two main groups of issues. The parties for whom the contract is made, the subjects of justice, have traditionally been viewed as the parties who contract. But many disabled or infirm people, children and, of course, animals cannot contract. So they would seem to be excluded from the scheme of justice, from the obligation to act justly towards them. Compassion may be enjoined, but not justice, which is an artifice of contract. But secondly, what advantage is there in contracting with those who are less than roughly equal, those from whose cooperation there can be no adequate reciprocal gain? The logic of mutual advantage excludes the disabled and helpless, and, mutatis mutandis, poor nations and animals. The book’s critical engagement at these frontiers, especially in relation to the disabled, is conducted with great sensitivity and effect; however, its contention that relations between nations should be governed by principles of justice akin to those prevailing within nations seems inadequately secured, and the insistence that relations with animals should also be regulated by justice, though appealing, leads Nussbaum to conclusions that are a little loopy.

Passing from critique to construction, Nussbaum develops and applies the capabilities approach in detail. The method is to provide a list of bare minimum human entitlements which must be implemented in any just political dispensation: ‘a society that does not guarantee these to all its citizens, at some appropriate threshold level, falls short of being a fully just society, whatever its level of opulence.’ The list includes such basic matters as: good health and nourishment, adequate housing, being able to laugh and play, and participation in political processes that affect one’s life. Creating the conditions in which these entitlements are implemented generates the political principles of a liberal, pluralistic society.

But how are these entitlements selected and justified? ‘The basic intuitive idea ... is that we begin with a conception of the dignity of the human being, and of a life that is worthy of that dignity – a life that has available in it “truly human functioning”.’ Such functioning requires the exercise of certain capabilities: ‘the idea of what human beings need for fully human living is among the most vivid intuitive ideas we share.’ Corresponding to these capabilities, then, are the entitlements to exercise them, implicit in the very idea of human dignity. Moreover, ‘if human beings have such entitlements, then we are all under a collective obligation to provide the people of the world with what they need’.

These are bold, attractive, but unfortunately problematic moves. The inference from individual entitlement to collective obligation is invalid. And it is far from clear that any conception of human dignity, even one as rich as the Aristotelian–Marxian conception that Nussbaum elaborates, can be rich enough to support the entitlements she proposes. Defensible they may be on other grounds, but it is not self-evident that even some of the minimal entitlements (adequate housing or democratic freedoms, for example) are inherent in the idea of human dignity. When Nussbaum proceeds to extract the entitlements of animals from the conception of animal dignity, the result is reductio ad absurdum. ‘Probably the euthanizing of aged animals is more often permissible than the euthanizing of humans,’ she concludes; and ‘some animals also have entitlements to suitable education’.

The deep insight of this book is that the egoistic moral psychology underpinning much current economic and political thought is disastrously impoverished. The good of others is also a part of my good. ‘Justice is also one of our ends.’ This insight will be pursued in Nussbaum’s next, foreshadowed tome, Capabilities and Compassion.