For example, what would be inappropriately off topic to post to LessWrong discussion about?
I couldn't find an answer in the FAQ. (Perhaps it'd be worth adding one.) The closest I could find was this:
What is Less Wrong?
Less Wrong is an online community for discussion of rationality. Topics of interest include decision theory, philosophy, self-improvement, cognitive science, psychology, artificial intelligence, game theory, metamathematics, logic, evolutionary psychology, economics, and the far future.
However "rationality" can be interpreted broadly enough that rational discussion of anything would count, and my experience reading LW is compatible with this interpretation being applied by posters. Indeed my experience seems to suggest that practically everything is on topic; political discussion of certain sorts is frowned upon, but not due to being off topic. People often post about things far removed from the topics of interest. And some of these topics are very broad: it seems that a lot of material about self-improvement is acceptable, for instance.
There was just an astonishingly civil examination of the most mindkilling topic I could think of in Discussion. I've criticized people for violating the LessWrong politics taboo in the past, but I'd be happy to chat about anything from particular elections to the merits of Marxism if it was always done so painstakingly in the articles and so thoughtfully in the rebuttals.
I'm not sure how to achieve that, though. "Everybody can talk about politics carelessly" isn't any better an idea than it was before, and trying to enforce "only talk about politics carefully" might just add tone arguments without actually improving the tone.
Abortion is a strongly mindkilling topic for society in general, but it is not one for Less Wrong. According to Yvain's survey data on a 5-point scale the responses on abortion average 4.38 + 1.032, which indicates a rather strong consensus accepting it. As a contrast, the results for Social Justice are 3.15 + 1.385. This matches my intuitive sense that discussions of social justice on LW are much more mindkilling than discussions of abortion.