The preceding comment by Jonathan reminded me of an earlier exchange I had with him on topic in -- of all places -- a Peikoff/Harriman thread. Looking back, it might be that Jonathan missed it. I don't yet see a reply. I include just the pertinent parts: Even sharper situations I can think of: if I live for another twenty-five years, say, until 2040. There is going to be a point on that road where I would get doubtful about my understanding. If the arctic regions of Canada began to experie