In The Idea of Justice Amartya Sen criticises ‘transcendental institutionalism’ for entertaining notions of ‘ideal justice’ that, are neither necessary nor sufficient for the advancement of justice in the real world. Sen argues in favor of a ‘realization- focused’ and ‘comparative’ understanding of justice that he associates with the names of Adam Smith, Marx, and J. S. Mill. Conceptions of ideal justice. Sen believes, are useless since in practice we do not need them to advance justice. And they are ‘infeasible’ because all conceptions of ideal justice can be reasonably rejected for one reason or other. I shall address both complaints in turn and maintain that Sen’s rigid contra-position of ideal and comparative justice is overstated. It will also be discussed how the institutional focus of ‘transcendental institutionalism’ links up with the need for an ideal conception of justice. Finally, some implications of rational dissent about justice and two common strategies to deal with it will be discussed.