A 1997 article written by author Keith Augustine entitled “The Case Against Immortality” sets out to define the problem as thus:
“Is there life after death? This question has been asked since the dawn of civilization. It is arguably the most important and most personal question that can be asked in light of the realization of one's own mortality. Immortality is a complex issue dependent on several other philosophical questions which need to be addressed."
Do we have scientific evidence to prove it true? No. Do we have evidence capable of being recorded with the aid of audio-visual devices or photographic technology? No. Do we have professed eye-witness accounts of someone “coming back from the dead?” Yes. Is it trustworthy testimony? Without being able to verify it independently or to repeat it, I would have to say no.
You can assume it’s correct. You can choose to believe it with all your mind, heart and soul. But to make the leap from historic, cross-cultural human testimony to total, complete intellectual certainty about things that are out of line with all known laws of physics is a leap I wouldn’t advise making.
The basic problem is that what people consider “evidence” can be conceptualized either very narrowly or very broadly. And both have their problems.
Define it very broadly and yes, you could present some “evidence” for life after death. If by evidence we mean anything which someone believes in their heart to be true is in fact true, why wouldn’t there be? Belief. Confidence. Trust. Assurance. If all that mattered was for someone to summon one of these types of emotional and cognitive states in order for something to qualify as evidence, then surely you could argue that life may indeed exist after death. But so could just about anything and everything that comes into a person’s head. People talk themselves into believing in UFOs, alien abductions, lizard people living under the earth, reincarnation and all kinds of bizarre ideologies and belief systems because of loosely-defined criteria for evidence.
But define what constitutes evidence too narrowly and we also run into problems. Are the only things which are real those things which we can replicate through scientific experimentation or analyze with one of our major senses, such as sight, sound or touch? Is human testimony never to be trusted as a source of truth or as evidence? Answer yes and we might find ourselves denying that humans ever landed on the moon or that the earth is round. You can’t tell it’s round just by looking at it can you? In another sense, even so-called first hand evidence requires us to assume that our senses can be trusted in what they are telling us and that the three dimensional, space-time universe we seem to live in has some basic degree of order and continuity to it.
Augustine, referencing in part a sermon by Jonathan Edwards called “Dependence,” writes:
“Immortality is related to the mind-body problem and the problem of personal identity in philosophy. The mind-body problem is concerned with how the mind and body are related to each other . . . . Modern materialism contends that mental states are reducible to physical brain states. Thus, if materialism is true, survival in the form of disembodied minds or astral bodies is ruled out automatically. Epiphenomenalism, which contends that the mind is a separate yet dependent by-product of the brain, has the same implications for survival. Resurrection is compatible with both of these theories of mind. A dualism that contends that the mind is a separate, independent entity from the brain is a necessary presupposition for the possibility of disembodied minds or astral bodies."
Again, you can choose whether you want to apply a very loose standard of evidence on which to base your essential beliefs, or a very broad standard, but I’d warn you not to get too hung up on issues of certainty, especially if it comes down by way of human recollection and folklore passed along from generation to generation -- or if there is some institutional benefit or vested interest in perpetuating the belief. In a court of law, human testimony is notoriously prone to error. People make things up, levy false accusations, tell outright lies, sometimes even convince themselves of things that are plainly untrue. There have been cases where the accused have plead guilty to things they were completely innocent off.
Immortality is the dream of a lot of us, myself included. However, coming up with the kind of genuine, hard evidence to justify a belief in life after death is something that has yet to be demonstrated.