The problem of moral personhood focuses on determining which beings are members of what we might call the moral community. The moral community consists of all those beings who have moral duties, rights, or, in general, deserve moral consideration. Medieval theologians speculated about whether angels were members of the moral community and thereby had the same moral duties as humans. Science fiction fans speculate about whether aliens from other worlds would have fundamental rights. Animal rights advocates contend that at least some animals have the same moral status as humans.
Medical ethicists struggle to determine whether permanently comatose humans have any rights.
The issue in all of these cases involves what it takes to be a morally significant person. A morally significant person is any being who is a member of the moral community. Several criteria of moral personhood have been suggested. Jains frequently wear cloths over their mouths to avoid accidentally inhaling bugs, and they sweep paths before themselves to keep from stepping on insects. Few people in our part of the world agree with the Jain criterion of personhood.