Fluorine has a protecting action against caries, but this is a local effect. If you drink it, you are running the risk of all kinds of toxic actions.
No planet is more earth-like than Earth itself, so if life really does pop up readily in earth-like conditions, then surely it should have arisen many times right here on our home planet? And how do we know it didn't? The truth is, nobody has looked.
I have always been willing to admit when I made a mistake. I made a mistake in my understanding of the composition of the Contras, not on my opposition to the Contra war.