[PatrickHenry]

Just as there is no universally accepted definition for life, there is no universal definition for human or for human life.

I'm sure that's true. But at the extremes there would probably be general agreement. For example, those rare cases where a baby is born with no cerebrum.

[js1138]

This is dangerous ground. The Nazis killed retarded people of all ages; the lovely and Utopian Sweeds were sterilizing "defective" people long after other western countries outlawed this form of eugenics.

We, of course, are more civilzed. For retarded people who live on welfare, most females are required to take birth control pills in order to qualify for housing. I leave it to you to decide the morality of this. It is definitely utilitarian.