– I don’t know what you are talking about.

You two have been talking for about half an hour. You are trying to get your point across, he is doing the same. Healthy, nice, warm debate. Then when you reach that place, that almost intangible place, where he knows he will be left without his (un)carefully welded armor of truths, he says: “I don’t know what you ‘re talking about”. Of course he doesn’t.  You can try to explain it again, say it in other words, it doesn’t matter. “You’re making no sense”. He wants to not think about it. For you it’s left a decision: is it arrogance or cowardice?