• difference principle;
  • social mobility;
  • tax credits;
  • negative tax rate;
  • John Rawls;
  • second-best

Outside academia, John Rawls's theory of justice—justice as fairness—has had little impact. This article is part of a broader project to rectify this. I offer a distinctive, second-best, argument for Rawls's difference principle. The difference principle requires that inequalities in income and wealth are justified only if they benefit society's least-advantaged citizens. My paper argues that, slightly-modified, the difference principle is an excellent principle of redress in light of the UK's continued failure to give all citizens fair career chances. I show how we might realize the difference principle at the level of policy through tax rate reductions or negative tax rates. I conclude that if you don't want to accept the second-best argument for the difference principle you must get serious about giving all citizens fair career chances. As I suggest, this task is extremely difficult.