 We do not strive (when we do strive) to treat human infants and children, the senile and the severely disabled as fully human because we mistakenly attribute capacities to them that they lack, or because we are blind to the merely biological significance of a species boundary. We do it (when we do) because they are fellow human beings, embodied creatures who will come to share, or have already shared, in our common life, or whose inability to do so is a result of the shocks and ills to which all human flesh and blood is heir—because there but for the grace of God go I. (Mulhall 2002, 7)