Cohen's argument had both philosophical and political dimensions. Philosophically, it exposed an ambiguity in Rawls's treatment of the basic structure. Rawls held that the principles of justice apply primarily to the basic structure, not directly to individual actions within that structure. Cohen argued that this division breaks down when the relevant inequalities depend on individuals' unwillingness to produce without outsized rewards — that is, when the inequalities are sustained by individual choices rather than by structural necessity. Under those conditions, Cohen argued, justice requires attention to individual ethos as well as to institutional design.
Politically, Cohen's critique aligned with a more ambitious egalitarian project than Rawls's. Rawls's framework permits substantial inequality provided it benefits the least advantaged. Cohen argued that even permitted inequalities could be unjust if they rested on an ethos of self-interested rent extraction incompatible with a genuine commitment to community. A just society, for Cohen, would be one in which the talented exercised their talents for reasons compatible with solidarity, not merely for personal gain.
Applied to the AI transition, Cohen's framework sharpens the critique of current arrangements. The astronomical returns captured by AI company shareholders and executives are not obviously the minimum necessary to produce the gains that AI delivers. Most AI development is done by engineers and researchers whose motivations include scientific curiosity, the pleasure of building complex systems, and the desire to contribute to valuable work — motivations that do not require the specific form of compensation that current arrangements provide. If these practitioners would continue to produce AI at substantially lower compensation, the excess compensation represents rent extraction rather than incentive, and the inequalities it generates fail the difference principle on its own terms.
Cohen's challenge has not displaced Rawls but has sharpened him. Contemporary Rawlsian theorists increasingly distinguish between the formal satisfaction of the difference principle (current inequalities nominally benefit the least advantaged compared to some counterfactual) and its substantive satisfaction (current inequalities are genuinely the minimum necessary, rather than permitted rent extraction). Cohen's work makes this distinction methodologically central.
Cohen was born in Montreal in 1941 to a Jewish communist family. He studied at McGill and Oxford, taught at University College London for nearly two decades, and held the Chichele Chair of Social and Political Theory at All Souls College, Oxford, from 1985 until his death in 2009. His major works include Karl Marx's Theory of History: A Defence (1978), Self-Ownership, Freedom, and Equality (1995), If You're an Egalitarian, How Come You're So Rich? (2000), and Rescuing Justice and Equality (2008).
Incentives critique. Inequalities justified as incentives are not genuinely justified if the talented would produce the same output at lower compensation.
Ethos and basic structure. Justice requires attention to individual ethos, not merely institutional design; the sharp division Rawls drew between the two is unsustainable.
Rent extraction versus incentive. Current market outcomes frequently represent rent extraction rather than genuine incentive necessity — a distinction the difference principle must police rigorously.
Internal critique. Cohen's method was to accept the Rawlsian framework and show that, properly applied, it demanded more than Rawls himself permitted.
Egalitarian ethos. A fully just society would be one in which the talented exercised their talents for reasons compatible with solidarity, not merely for personal gain.