As I tell my students, the metaphysical question of personal identity has important moral implications. One scenario I present is that of a human in what seems to be a persistent vegetative state. I say “human” rather than “person”, because the human body in question might no longer be a person. To use a common view, if a person is her soul and the soul has abandoned the shell, then the person is gone.
If the human is still a person, then it seems reasonable to believe that she has a different moral status than a mass of flesh that was once a person (or once served as the body of a person). This is not to say that a non-person human would have no moral status at all—I do not want to be interpreted as holding that view. Rather, my view is that personhood is a relevant factor in the morality of how an entity is treated.
To use a concrete example, consider a human in what seems to be a vegetative state. While the body is kept alive, people do not talk to the body and no attempt is made to entertain the body, such as playing music or audiobooks. If there is no person present or if there is a person present but she has no sensory access at all, then this treatment would seem to be acceptable—after all it would make no difference whether people talked to the body or not.
There is also the moral question of whether such a body should be kept alive—after all, if the person is gone, there would not seem to be a compelling reason to keep an empty shell alive. To use an extreme example, it would seem wrong to keep a headless body alive just because it can be kept alive. If the body is no longer a person (or no longer hosts a person), then this would be analogous to keeping the headless body alive.
But, if despite appearances, there is still a person present who is aware of what is going on around her, then the matter is significantly different. In this case, the person has been effectively isolated—which is certainly not good for a person.
In regards to keeping the body alive, if there is a person present, then the situation would be morally different. After all, the moral status of a person is different from that of a mass of merely living flesh. The moral challenge, then, is deciding what to do.
One option is, obviously enough, to treat all seemingly vegetative (as opposed to brain dead) bodies as if the person was still present. That is, the body would be accorded the moral status of a person and treated as such.
This is a morally safe option—it would presumably be better that some non-persons get treated as persons rather than risk persons being treated as non-persons. That said, it would still seem both useful and important to know.
One reason to know is purely practical: if people know that a person is present, then they would presumably be more inclined to take the effort to treat the person as a person. So, for example, if the family and medical staff know that Bill is still Bill and not just an empty shell, they would tend to be more diligent in treating Bill as a person.
Another reason to know is both practical and moral: should scenarios arise in which hard choices have to be made, knowing whether a person is present or not would be rather critical. That said, given that one might not know for sure that the body is not a person anymore it could be correct to keep treating the alleged shell as a person even when it seems likely that he is not. This brings up the obvious practical problem: how to tell when a person is present.
Most of the time we judge there is a person present based on appearance, using the assumption that a human is a person. Of course, there might be non-human people and there might be biological humans that are not people (headless bodies, for example). A somewhat more sophisticated approach is to use the Descartes’s test: things that use true language are people. Descartes, being a smart person, did not limit language to speaking or writing—he included making signs of the sort used to communicate with the deaf. In a practical sense, getting an intelligent response to an inquiry can be seen as a sign that a person is present.
In the case of a body in an apparent vegetative state applying this test is quite a challenge. After all, this state is marked by an inability to show awareness. In some cases, the apparent vegetative state is exactly what it appears to be. In other cases, a person might be in what is called “locked-in-syndrome.” The person is conscious, but can be mistaken for being minimally conscious or in a vegetative state. Since the person cannot, typically, respond by giving an external sign some other means is necessary.
One breakthrough in this area is due to Adrian M. Owen. Overs implying things considerably, he found that if a person is asked to visualize certain activities (playing tennis, for example), doing so will trigger different areas of the brain. This activity can be detected using the appropriate machines. So, a person can ask a question such as “did you go to college at Michigan State?” and request that the person visualize playing tennis for “yes” or visualize walking around her house for “no.” This method provides a way of determining that the person is still present with a reasonable degree of confidence. Naturally, a failure to respond would not prove that a person is not present—the person could still remain, yet be unable (or unwilling) to hear or respond.
One moral issue this method can held address is that of terminating life support. “Pulling the plug” on what might be a person without consent is, to say the least, morally problematic. If a person is still present and can be reached by Owen’s method, then thus would allow the person to agree to or request that she be taken off life support. Naturally, there would be practical questions about the accuracy of the method, but this is distinct from the more abstract ethical issue.
It must be noted that the consent of the person would not automatically make termination morally acceptable—after all, there are moral objections to letting a person die in this manner even when the person is fully and clearly conscious. Once it is established that the method adequately shows consent (or lack of consent), the broader moral issue of the right to die would need to be addressed.