I am teaching a class on freedom at Rhode Island College this semester, and in a fit of doubtless excess ambition I decided that one of the things I wanted to do was to carefully go through Kant's Groundwork for the Metaphysics of Morals. I take the book much more seriously than I used to. Of course, this is because I find the view and the arguments presented more interesting than I once did, but while I think I can explain what it is that I find in the work that I didn't always see (I certainly hope so, since I want to explain that to my students), I wonder whether the reason I found it is rationally suspect.
One of my favorite teachers, Tony Anderson, was a grad student at UCLA while Carnap was still alive. Carnap had retired by then, but Tony got the chance to meet him. Apparently Carnap had gone blind, and the UCLA philosophy department had a volunteer from among the graduate students help him out by reading his letters to him and writing replies for him. Tony enthusiastically volunteered for this job, and after dealing with the letters, he says that he and Carnap would talk about philosophy.
One story Tony tells about this time is that he was taking some class or seminar where Kant's moral theory was under discussion. He made some disparaging comment to Carnap about how silly some part of Kant's moral theory was, expecting Carnap to immediately agree (Carnap was, after all, a non-cognitivist). Instead, Tony reports that Carnap said "you shouldn't be so hasty. There is something to what Kant is saying there."
Tony tells this story to indicate that Carnap's reputation as a rigid and dogmatic thinker is undeserved, but while I certainly think that Carnap was in important senses quite open-minded, for me that explanation isn't quite satisfactory. I'm sure that's not what Carnap would have said if Tony had instead made a comment about, say, Heidegger. It seems to me that the only reason Carnap would have said there was something to what Kant was saying was if he thought that there was something to what Kant was saying. So this story puzzled me for a long time; I wondered what Carnap though there was in Kant's moral theory that was on the right track. And that's what I, these days, think I've figured out.
Of course, one of the things this story emphasizes is the contingency of our (or at least my) knowledge. The path by which I was led to the insight in question (if it is one) seems utterly accidental. I do not know exactly what lessons to draw from that.