 But the claim that justice only applies to participants in co-operative practices is anyway vulnerable to the objection that it risks excluding seriously disabled people, people living in isolated communities, and future generations from the scope of justice, so it does not seem compelling as a claim about justice in general (see further below). Might there be other reasons why animals cannot make claims of justice on us? Another Rawls-inspired suggestion is that animals lack the necessary moral powers, in particular the capacity to act on principles of justice themselves. They cannot distinguish what is justly owed to them from what is not; and they cannot determine what they owe to others – whether to humans or to other non-human animals – as a matter of justice. This suggestion interprets justice as involving a kind of reciprocity: an agent to whom justice is due must also in principle be an agent who could dispense justice to others, by virtue of having the relevant capacity, even if for physical reasons – such as suffering from severe disability – they cannot do so in practice.