An interesting debate
I’m with Mankiw on this one. To me, to compare the utility of those who have never been born with those who have been born does not make any sense. Also, I think there’s a big difference between never having been born, and having been born and committing suicide.
Caplan’s position is that we, by not committing suicide, reveal that humans in general prefer existence to non-existence, and that those not yet born would therefore prefer being born to not being born. But as I see it, we can’t conclude anything of the sort. What we know is that people who have already been born in general prefer life to death. Two problems arise. i) Maybe people who are already born have preferences that are different from those who have not yet been born. Maybe the very act of being born changes your preferences systematically. This question leads to the second problem: ii) The life and death comparison is not what we’re interested in here. What we’re interested in is instead the question of existence vs. non-existence. There’s no way we can answer this question, as none of us has any experience when it comes to non-existence. The non-existence option is simply not available to us, it was taken from all of us the moment we were born.
Death and non-existence are two very different things. They are not equivalent. Non-existence is a difficult concept to grasp. Asking what non-existence feels like is a little like asking what was “before” the concept of time even existed (which is, incidentally, what we ask about when we pose the question of what was “before the Big Bang”). We don’t know.