It amuses me that pilpul actually has a positive meaning in Judaism as a sort of rabbinical skill. A Jew would say something like: 'Wow, that rabbi has proven that he is an excellent rabbi, because he excels at pilpul!'.

Somehow this term eventually became synonymous with something negative, such as sophistry or even bullshit. I imagine that this was once Jews became prevalent in other societies and non-Jews thus observed their rabbis arguing amongst each other. A non-Jew would have once said something like: 'These rabbinical arguments are full of bullshit and sophistry, and they call it pilpul. Well, let's just call all sophistry and bullshit pilpul.'

Then it took on, probably initially as a sort of joke, and here we are in the present day, calling bullshit of all sorts pilpul, with no real idea of how that came to be.

Other points you've missed are relativism (e.g. 'I'll grant that your argument X is only true in a specific time &or place, but false in our current time &or place') and subjectivism (e.g. 'I'll grant that your argument Y is true in your reality, but isn't it only true for you or people like you and not true for me or people like me because there is no objective reality that we jointly inhabit?')

Shifting Christian attitudes on 'anti-semitism', e.g. Catholicism pre- versus post-Vatican II, for instance, could easily be defended by downgrading things from objectivism to relativism: 'You say that because we have changed our mind on the Jews that therefore we were either wrong for two millennia or are wrong now, and therefore that our religion must be false. However, the truth is that God changed His Mind when man reached a certain level of progress. Thus, we were anti-semites back then and we weren't wrong, and we are not anti-semites now and we aren't wrong. When we were primitive, anti-semitism was in line with God's Will; but now that we are Enlightened, God has revealed His new Will, and opposing anti-semitism is now in line with His Will. We were never wrong because anti-semitism was actually in line with God's Will all along; that is, it was a stage God Willed us to go through until man reached a certain level of progress and God revealed to us that He had changed His Mind. He had changed His Mind because harbouring grudges is unbefitting of Him - He had chosen to forgive the Jews - and, after all, such tolerance is more befitting of our Enlightened Age.'

Notice that such an argument would get the defender out of a double bind.