  The considerations above do not in themselves show, as Liam Murphy and Thomas Nagel (2003) have argued, that “Taxes do not take away from taxpayers what is antecedently theirs; pretax income has no status as a moral baseline for the purpose of evaluating the justice of the tax system.” Indeed, libertarians and others can still make out their case that rights-infringing redistribution has occurred by specifying and justifying entitlement producing rules that, if accepted, would grant pretax income significance as a moral baseline. They may argue, for example, that gross incomes have moral significance because they show the value of one’s contribution to social cooperation as assessed by others, or because they represent (at least roughly) differentials in what individuals contribute to total  production.[16]