An expansion of my comment policy

I've already made it clear that I will delete abusive comments. I've also had an informal policy of trying to promote on topic discussion on abortion threads, for example by providing one single thread where abortion may be discussed.

I'm going to expand this policy so that on some threads I will limit the sort of comments so that they don't get derailed. These will be put at the bottom of the post, and I will delete or move off-topic comments.

I should make it very clear that my intention here is not to provide a forum for political debate between the left and the right. There are plenty of places where that can happen. I think there's a lot of discussion that needs to happen between people who have a common starting point, and that discussion is what I am more interested in.