 Several critics have noted that there are metaphysical issues at stake in the original argument. The Systems Reply draws attention to the metaphysical problem of the relation of mind to body. It does this in holding that understanding is a property of the system as a whole, not the physical implementer. The Virtual Mind Reply holds that minds or persons – the entities that understand and are conscious – are more abstract than any physical system, and that there could be a many-to-one relation between minds and physical systems. (Even if everything is physical, in principle a single body could be shared by multiple minds, and a single mind could have a sequence of bodies over time.) Thus larger issues about personal identity and the relation of mind and body are in play in the debate between Searle and some of his critics.