According to A. K. Sen, liberalism (or ‘libertarianism’ as he now prefers to call it1) permits each individual in society ‘the freedom to determine at least one social choice, for example having his own walls pink rather than white, other things remaining the same for him and the rest of society’.

Sen contends that the value involving individual liberty illustrated by this example imposes a constraint on social welfare functions – i.e. rules which specify a ranking of social states with respect to whether they serve the general welfare better or worse given information about the preferences of individual members of society for these social states or their welfare levels in these social states. This constraint ‘represents a value involving individual liberty that many people would subscribe to’ regardless of whether it captures all aspects of the presystematic usage of the terms ‘liberalism’ or ‘libertarianism’.

Sen's condition L asserts that each citizen ought to have his preference ranking of at least one pair of social states determine the social ranking of the same pair of states with respect to welfare.

P. Bernholz pointed out that libertarians do not concede individuals rights to determine the social ranking of social states but to determine aspects of social states. P. Gärdenfors has recently combined Bernholz's observation with R. Nozick's suggestion that granting rights to individuals cedes to them the ability to constrain the domain of social choice to a given class of social states.

In his interesting discussion of Nozick's idea, Sen points to an ambiguity in the interpretation of a social ordering.