We both agreed to the statement that killing human beings is morally bad. Now, the definition of a human being came up.
Ah, careful. If you’ve already decided that killing human beings is morally bad, you must already have a partial definition of “human being” in mind: A thing is a human being only if killing it is morally bad. Now in order to establish that a fetus is a human being, you need to first establish that killing it is morally bad.
Better to not worry about the definition of “human being” at all. Decide what makes killing adults bad, and see if it applies to fetuses. You’re basically doing this already when you consider the coma patient. It would be good to make sure your friend is on the same page.
Ah, careful. If you’ve already decided that killing human beings is morally bad, you must already have a partial definition of “human being” in mind: A thing is a human being only if killing it is morally bad. Now in order to establish that a fetus is a human being, you need to first establish that killing it is morally bad.
Better to not worry about the definition of “human being” at all. Decide what makes killing adults bad, and see if it applies to fetuses. You’re basically doing this already when you consider the coma patient. It would be good to make sure your friend is on the same page.