Otherwise how do I figure out what I don’t know?

A related question: do you ever get that feeling where you say something (if you're lucky you might stop yourself first) about something that you learned before becoming a commiewithoutorgans and realise it's ludicrous? I do that so often. It's like only the new memories and information have been re-framed. Much of the old memories and information is sat in an archive in the back of my mind, complete with a perfectly intact liberal outlook.

Back to your question: when this happens to me it takes a [span of time] to realise that although I have an answer, I don't actually know what I'm talking about. If yours wasn't a rhetorical question, I don't have a great answer other than to say: try to recall where you learned what you think you know and when. If the answer isn't The Collected Works of Lenarx Dengping and/or 'recently', I try to err on the side of caution.