People don't realize that molecules themselves are somewhat hypothetical, and that their interactions are more so, and that the biological reactions are even more so.

If reincarnation is a useful biological idea it is certain that somewhere in the universe it will happen.

PCR made it easier to see that certain people are infected with HIV.

Here's a bunch of people practising a new set of behavioural norms. Apparently it didn't work because a lot of them got sick. That's the conclusion. You don't necessarily know why it happened. But you start there.

Art is subject to arbitrary fashion.

I can say exactly what I feel about any issue, and I'm going to do that.