[jcr]

If you haven't studied rhetoric, rationality, and statistics, then you'll always be at a disadvantage in a discussion. Ask him to write down the idea, the proposal, and the rational. Once you have it written down, defang the rhetoric and then try to do fair minded due diligence.

[throwaway1001]

Not sure writing down will help. His own words: "In the bank, when we were preparing slides for an M&A that buyer will clearly won't benefit from, we were honestly describing all the risks, but for each point there we were able to invent 1000 ways to mitigate it if we wanted to".

I guess, he's similarly convincing in writing as well.