Last weekend I met up with an old college friend to play Go and hang out. We ended up playing less than planned and instead arguing philosophy for five hours or so. In the ten years I've known him his opinions and lifestyle have undergone a radical shift: he's gone from being a Washington State conservative creationist evangelical to an enthusiastic but temporary Episcopalian to a Washington D.C. liberal materialist atheist. This particular night the discussion began when he casually mentioned that he wished it had been made clear in our undergraduate program that pretty much all of pre-20th century philosophy had been decisively refuted by modern science. After this a lot of conversation was spent with him simply delineating his new positions and with me trying to find some first principles we could agree on which could constitute a starting-point for a real debate. In the end I couldn't find any.
This was rather disturbing and I had a very odd feeling throughout the conversation. Here was an old and close friend telling me that he couldn't admit it as true in any strong sense that there was a tree outside the window, or that the conventional notion of a 'tree' had any extramental correlate, since what we called a tree was simply an arbitrary bundling together of those aspects of sensible phenomena which happened to interest us at a given moment; that there was no unity in the object itself, since there was no object itself, since all self-identity was an illusion; that there was no true identity of any kind, and that every single aspect of the world was simply in constant flux, and so we couldn't identify the unity of an object by the unity or continuity of its operations, since these were also illusory; that therefore the continuity of motion and the unity or identity of any act also had to be abandoned; and, finally, that he knew all this beyond any doubt because it had been established by "Science".
I tried to suggest that if all this were true then the foundations of science would themselves be undermined, and with them all his confidence in what "Science" supposedly teaches, but he didn't bite. Sure, science is just a series of useful stories we tell ourselves in order to render the world more functional - so what? They're the best stories we have, and they work just fine. I suggested that his picture of the world reduced literally everything to absurdity, including the meaningfulness of calling something an illusion when there is no "me" from moment to moment to have the illusion and no definite and intelligible reality for me to have illusion about: nowhere to see through the illusion to. He was unfazed. Yes, that's the way things are. Since what we call "thought" is simply an algorithm executed by our brains for maximum consciousness-efficiency, why should we expect it to have some correspondence to reality?
So I have to admit that I'm not a good enough Socrates to get anywhere beyond this. What do you do when your interlocutor doesn't mind if his position is, by any reasonable standard, absurd? After hours of argument I couldn't find a single thing we could both agree was true. Not even "I am thinking this thought" or "The people having this conversation now are the same people who were having it an hour ago." I'm tempted to say that at this point there is simply a philosophical breakdown, that there is nowhere to go from here.
