So does after death exist or not?
Certainly from a living perspective the observer can see a corpse, so for that perspective after death exists.
Yah, the now inanimate body remains as fact, but there's no subjective or personal verification of the condition of being dead -- or "this one" being absent consciously and identity/memory wise from the Earth. As Bering mentions below, there's a kind of private immortality between the boundaries of the first increments of awareness in the womb and the last ones (hopefully many years later).
Jesse Bering:
Consider the rather startling fact that you will never know you have died. You may feel yourself slipping away, but it isn’t as though there will be a “you” around who is capable of ascertaining that, once all is said and done, it has actually happened. Just to remind you, you need a working cerebral cortex to harbor propositional knowledge of any sort, including the fact that you’ve died—and once you’ve died your brain is about as phenomenally generative as a head of lettuce. In a 2007 article published in the journal Synthese, University of Arizona philosopher Shaun Nichols puts it this way: “When I try to imagine my own non-existence I have to imagine that I perceive or know about my non-existence. No wonder there’s an obstacle!”
This observation may not sound like a major revelation to you, but I bet you’ve never considered what it actually means, which is that your own mortality is unfalsifiable from the first-person perspective. This obstacle is why writer Johann Wolfgang von Goethe allegedly remarked that “everyone carries the proof of his own immortality within himself.” --
Never Say Die: Why We Can't Imagine Death
If the philosophy of time view called
eternalism was metempirically correct (i.e, all moments or different states of the universe co-exist) then your whole lifetime would literally never cease to be and has always existed.
As H.G. Wells put it in "The Time Machine" and
Hermann Weyl decades later, only the consciousness (phenomenal experiences) of an organism actually "moves" in a block-universe. (Though I'd contend that even that is figurative or an illusion, but too much of a detour to explore here. Suffice it to say that their older, clumsier conception is quicker.)
Contrasting with eternalism is of course presentism, wherein the "next now" replaces and obliterates the immediate one -- the past and future accordingly don't exist, only each fleeting, new universal "now".
Then we would have to define person in a way that doesn't provide contradiction for if a person (ego-identity) is merely attributes of a living physical body then after death exists as a corpse. ( ashes to ashes etc)
However if one wishes to consider that the ego id etc. is somehow special or aloof to the physical then, claiming that the ego or identity no longer exists after death is a rational position, but to do so contradicts the previously mentioned claim that the living body is all that there is to begin with and continues to exist in a dead state as a corpse.
It is quite intuitive to feel that the mind/body duality is real yet one wonders whether the non-dualism that medical science is suggesting is more the reality.
There's only so far I could go in being a devil's advocate for slash defender of physicalism or methodological naturalism, when treated as ultimate reality. Since I pretty much regard such in an epistemological context as being the best way for understanding and manipulating the affairs of the phenomenal world.
While there could be neural correlates with unique signatures of activity, the emergence of phenomenal experiences (the manifestations of consciousness) can't be detected publicly in the brain either as some weirdo "new field" that has emerged or new properties that matter or electrochemical activity has suddenly acquired. So brute emergence is clearly along the line that brain processes have either conjured or summoned something utterly radical that is dualistic (cannot be publicly detected/verified, though privately you can apprehend those presentations and feelings being there).
The alternative is a softer type of emergence (sans conjuring) where the brain is merely arranging and jacking-up in complexity internal states that matter already has, but likewise cannot be detected. The plus to that view is that by making experience fundamental (proto-panexperientialism, anyway) you eliminate the appearance of magic that's associated with brute or strong emergence. And its blatant dualism, too. (However, matter throughout the universe having a "double-aspectism" is then introduced: extrinsic states that physics deals with and intrinsic states that only a sophisticated cognitive system can finally verify to itself as being the case).