The original Shackel paper is intended as a critique of post-modernism.Post-modernists sometimes say things like “reality is socially constructed”, and there’s an uncontroversially correct meaning there.If an enemy approached, you would retreat to the motte and rain down arrows on the enemy until they gave up and went away.
“Well, Hell is just another word for being without God, and if you choose to be without God, God will be nice and let you make that choice.” (motte) Oh, well that doesn’t sound so bad, I’m going to keep rejecting Jesus. The feminists who constantly argue about whether you can be a real feminist or not without believing in X, Y and Z and wanting to empower women in some very specific way, and who demand everybody support controversial policies like affirmative action or affirmative consent laws (bailey).
So the motte-and-bailey doctrine is when you make a bold, controversial statement.
Then when somebody challenges you, you claim you were just making an obvious, uncontroversial statement, so you are clearly right and they are silly for challenging you.
For example, “Religious people say that you should kill all gays. If you’re debating the Pope or something, then when you weak-man, you’re unfairly replacing a strong position (the Pope’s) with a weak position (that of the guy who wants to kill gays) to make it more attackable.
But in motte and bailey, you’re unfairly replacing a weak position (there is a supernatural creator who can make people out of ribs) with a strong position (there is order and beauty in the universe) in order to make it more defensible.