Person

Firstly, there is the simple view that the common usage is the correct one: that person does indeed mean human. However, this runs into the problem that the term person has a somewhat loaded meaning - we commonly believe that all and only persons have certain rights, for example, the right to life. Some would go so far as to say that all and only persons are sacred. However, we can imagine the hypothetical alien from another planet, who, despite not being human, nevertheless has every trait that we see as being essential for this protected status that elevates it above mere objects. Thus, many claim that the simple view implies a sort of arrogant speciesism.

Another problem with the simple view is that there are disputes over whether certain humans are persons. For example, in the abortion controversy, although the foetus is clearly of the human species, it is a matter of debate whether it is a person. Or in the case of a victim of severe brain damage who has no mental activity, it may be claimed that he or she is no longer a person, merely an "empty shell".

The above points seem to indicate that there may be persons that are not human, and there may be humans that are not persons. For these reasons, many philosophers have tried to give a more precise definition, focusing on some trait or traits that all persons, real and hypothetical, must possess.

The most obvious such trait that persons typically possess is a conscious mind, typically (but not necessarily) with plans, goals, desires, hopes, fears, and so on. Yet the claim that such a mind is necessary for personhood is also problematic, as most would consider human babies as persons, yet their minds do not seem sufficiently advanced to satisfy this condition. A few philosophers have simply accepted that babies are not persons. However, most have not. Instead, some have suggested that the potential for such a mind is the correct trait.

Yet another view is that personhood is not all-or-nothing: there can be degrees of personhood, based on how close to a fully working mind the object in question has. Thus, a typical adult is entirely a person, while a human permanently in a coma is not a person at all. This view also seems to have some unpleasant consequences, for example, that a young child or someone with a moderate mental handicap might be, say, only half a person (and perhaps therefore have only half the rights, or be regarded as half as important).

It is probably true to say that other views also exist, and that the debate is not close to being resolved.