It seems that there are a few different trends in thoughts on sexual consent among modern liberal/progressive culture. I'm always trying to improve myself and my behavior, so I try to take in as much information as I can on these fronts, but I've long since stopped making headway against a few hurdles.

In particular, there are two specific positions that I can't figure out how to reconcile. They boil down to these:

1. You can never be sure that the sex you're having is consensual, because consent depends on the current thoughts and mental state and/or later reflection and understanding of your partner(s).

2. You should not have sex if you aren't sure that it's consensual.

I see many people advocating one or both of these positions, but haven't managed to engage any of them in a discussion that has led to understanding on my part.

I would appreciate any insight y'all might have to share on this topic.