great point and raises many questions. makes me leery of... well, of everybody... including Wilber. He says, "the point is that these are authentic spiritual experiences, but they are culturally molded". can we really say this? can we really pretend to know what "authentic spiritual experiences" are? His confidence about impossible to define/understand concepts is hard for me to endorse... then again, he's been a real pioneer in this area and maybe this comes from a different cultural angle.
I can definitely relate to the leery of everybody sentiment.
I guess we're stuck with the problem that we can't 'prove'
any subjective experience - 'spiritual' or otherwise. All we have is that notion that because our own subjective states seem to reflect other people's subjective states so consistently, we generally allow ourselves to deduce that those subjective states are 'real' or authentic. I know that Wilber argues(particularly in his book The Marriage of Sense and Soul)that this applies to 'objective' science too, since science is ultimately experienced subjectively. This is where he makes his case that there is valid 'empirical' evidence for subjective and 'spiritual' realities.
First he argues that all 'empirical' evidence is
experiential evidence. Then he posits three essential aspects for scientific inquiry:
1. Instrumental injunction."This is an actual practice, an exemplar, a paradigm, an experiment, an ordinance. It is always of the form "If you want to know this, do this."
2. Direct apprehension. "This is an immediate experience of the domain brought forth by the injunction; that is, a direct experience or apprehension of data (even if the data is mediated, at the moment of experience it is immediately apprehended)."
3. Communal confirmation (or rejection). "This is a checking of the results—the data, the evidence—with others who have adequately completed the injunctive and apprehensive strands"
His argument is that the contemplative spiritual traditions adhere to these same rules for validating truth claims as much as the physical sciences. You could easily extend that to NDE experience, too.
Of course, as I'm sure you are already thinking, that's a nice shot but the materialists like Dawkins etc. will have already dismissed all of this as unworthy of their consideration just by seeing the word "soul" on the cover of the book.