What, if anything, is wrong with affirmative action?

Affirmative action can be defined as the process of giving some form of favouritism to previously or currently disadvantaged groups of society with the aim of bridging inequalities, especially in employment and education admissions. 

Liberal political philosophy has often defended affirmative action, especially under the broader framework of distributive justice, equality of opportunity and moral desert. And this defence has been particularly strong within deontological liberalism –although not exclusively (e.g., Sher, 1975:159-170). Deontological liberalism, also referred to as Rawlsian liberalism or simply political liberalism, is an account of liberal philosophy that asserts the priority of the right over the good, as opposed to teleological liberalism, which upholds the priority of the good over the right.