The demandingness of Nozick's 'Lockean' proviso

Interpreters of Robert Nozick's political philosophy fall into two broad groups concerning his application of the 'Lockean proviso'. Some read his argument in an undemanding way: individual instances of ownership which make people worse off than they would have been in a world without any ownership are unjust. Others read the argument in a demanding way: individual instances of ownership which make people worse off than they would have been in a world without that particular ownership are unjust. While I argue that the former reading is correct as an interpretive matter, I suggest that this reading is nonetheless highly demanding. In particular, I argue that it is demanding when it is expanded to include the protection of nonhuman animals; if such beings are right bearers, as more and more academics are beginning to suggest, then there is no nonarbitrary reason to exclude them from the protection of the proviso.