Tuesday, 3 October 2006
Kant and Bohr
The talk had been short, roughly 30 minutes, and it had been presented quite clearly. The questions and discussion had picked up quickly and showed no sign of losing energy. Yet I was not happy. What had started as requests for clarification had slowly evolved into disputation. Indeed I knew that I was in large measure to blame and that was not something to be proud of.
The idea of the talk was quite clear. The problems of the philosophical foundations of quantum theory have perplexed everyone who has seriously thought about them. Hernan saw an answer that combined his two great interests. He had first studied physics, but then turned to philosophy for its insights, finding in Kant's original works a kind of satisfaction not to be had from later elaborations. Hernan now saw that there was a deep connection between Kant's philosophy, and especially his discussion of symbols, and Bohr's interpretative writings on quantum theory.
To hear Hernan speak and then answer questions is to hear someone who is thoroughly steeped in the writings of both Kant and Bohr. He announces with a deep assurance just what it is that Kant or Bohr hold of this or that view; and anyone listening can have no doubt from the precision of words that he could back up everything with copious quotations. Objects can only be said to exist in so far as they organize and systematize sensations, he announces (as best as I can recall). I wonder, does he mean Kant's things in themselves or Bohr's quantum objects? And then I realize it doesn't matter. It could be either. That's the point.
The early questions probe Hernan's presentation of Kantian notions. Has Hernan really done justice, for example, to Kant's view of causality, Boris asks. Will anyone press Hernan on Bohr? No one seems to be, so I think I'll try. I ask Hernan why he takes Bohr's views as a datum to be explained, when they just seem to be wrong. Bohr says that we can only describe the quantum world through a classical vocabulary, whose terms may not all be applicable according to the measurement context at hand. Why, I ask, isn't it a perfectly acceptable description of the quantum realm to say that the quantum states form a Hilbert space whose dynamics is given by the Schroedinger equation... Hernan has heard it before and cuts off the question several times in his eagerness to answer. So the back and forth begins, with others joining in. Bohr has few friends in the room.
As the discussion proceeds, I can see an Atlantic divide in how people in the room present ideas. On the one side there are voices that do not present their own ideas. Every notion is attributed. "Kant would say..." "Bohr would say..." That is the reverence for tradition of the Old World. Then there is the brashness of the New World, willing to denounce Bohr as confused, in terms that one would never dare to present to Bohr's face.
The air is combative and I don't think it can be turned. But now I know how the discussion can turn to productive avenues. That difference of method must be our focus. I had already planned with our small group of Visiting Fellows that this evening after the talk we would meet for a leisurely discussion of today's talk. That is what I shall offer for discussion, that is, if no one has a better idea.
Shortly after the talk, when Hernan had satisfied those who hung back to ask their private questions, I found him standing in the lecture room. I walked up to the announcements of forthcoming talks and pointed to my name. I had been invited to speak on my paper "Causation as Folk Science." I told Hernan that they invite me because they cannot believe that anyone would seriously defend the idea that there is no principle of causality fundamental to science. It gives them reassurance to know that there is someone even more confused than they are, I quip.
"What can I do," I asked him, "I firmly believe in the view and I will defend it." "I understand," Hernan said, "I've been in that same situation."
John D. Norton
12:05 pm, Tuesday, 3 October 2006