Well, no matter how rational you are, it is still your conscious self that is perceiving the physical world and is just trying to makes sense of it. What happens to "you" after the death is really not related to understanding physical world, or at least not strictly dependant on the physical world. Which, at least for me, it means anything is more possible than just oblivion.
The not-knowing factor (of what happens in your life) is what drives most people to live, so why wouldn't give one a positive drive to actually live life and find out the same thing about death. You just don't skip high school to find out things what life in 40s will be like. :)
Edit: I hope I did't invoke illusion of being religious in any way. It's a purely philosophical way of questioning something you cannot possibly know.
Edit2: Also, other repliers (that obviously read more books than me) explain some really great theories
The not-knowing factor (of what happens in your life) is what drives most people to live, so why wouldn't give one a positive drive to actually live life and find out the same thing about death. You just don't skip high school to find out things what life in 40s will be like. :)
Edit: I hope I did't invoke illusion of being religious in any way. It's a purely philosophical way of questioning something you cannot possibly know.
Edit2: Also, other repliers (that obviously read more books than me) explain some really great theories