Matt McIrvin's Freaky Alternate Reality

In Pale Blue Dot, Carl Sagan suggests that -- if one has to draw a line as to when abortion is unethical -- five or six months is a good cutoff. His reasoning, if I recally correctly, was that it is at this point that the fetal brain develops to the point where it can have primitive thoughts and some something approximating an awareness or consciousness. Since self-awareness and a capacity for reason are what define us as human, the fetus is not human until that point (sayeth Sagan). I like his idea, and it's what I eprsonally believe in, although I guess technically the fetus isn't really human until it can exist outside its mother without an incubator.