I have always included a section on the afterlife in my Introduction to Philosophy class. As bit of grim humor, I tell my students that this is one philosophical problem that has a definite answer—unfortunately getting that answer requires dying.
Not surprisingly, students often point to examples of experiences in which people are technically dead, but are restored to life. People who survive these encounters with death often speak of strange experiences that they sometimes take as evidence for the afterlife.
One of the best publicized examples of this is the case of Dr. Eben Alexander, a Harvard neurosurgeon. After being put into a coma by bacterial meningitis, he had a death and revival experience which he has extensively publicized. He has also written up his experience as a book, the aptly named Proof of Heaven.
While Dr. Alexander’s case was given extensive media coverage because he is a Harvard neurosurgeon, his case is otherwise not significantly different from other such cases and can be assessed as they have been assessed. Naturally, it is worth noting that his medical training does give him credibility as an expert on neurosurgery. However, as an observer of the afterlife he would seem to be no more (or less) of an expert than anyone else. That is, his expertise in neurosurgery would not seem to apply to metaphysical experiences of the sort alleged to have occurred.
One stock criticism of the near-death experience is that a person who is revived is not properly dead. After all, they are revived shortly after death rather than resurrected or raised from the dead. As such, there is the rather legitimate question of whether or not they are even dead in a manner that would allow them to experience an afterlife, should it exist. They might just be “mostly dead” rather than “properly dead” and hence any experiences they have would not be experiences of the afterlife.
A second stock criticism is that the person who reports on near death experiences is not experiencing an afterlife, but is in a state of dreaming or hallucination that is mistaken for the afterlife on the basis that they were “mostly dead.” Critics routinely point to the similarities between near death experiences and drug experiences and the case of Dr. Alexander is no exception. It certainly makes sense that a dying brain would experience dream or drug like experiences that have no connection to the afterlife.
The cutting edge of these criticisms is to be found in Occam’s razor: the experiences can be explained adequately without postulating a metaphysical afterlife. As such, the explanation that the experiences are occurring within a dying (but still living) brain is the better explanation.
Aside from Dr. Alexander’s fame, there seems to be no real difference between his experiences and those reported by many other people before him. Given that these cases do not provide proof of heaven, then neither does his case.
Naturally, I would like to believe in the sort of wonderful afterlife claimed by Dr. Alexander. However, wishful thinking is not proof.