REPLY TO STEPHEN WHITE hilary putnaM

W i responded to stephen White’s deep and elegant lecture in rome, i said that i agreed with his transcendental argument and i do. it is a profound contribution to the discussion of the epistemology and phenomenology of perception. and apart from one minor textual issue having to do with William James,1 was so convinced by that lecture that i had no criticism to voice. But on a subsequent close reading of his paper, i have discovered an issue (one that he raises towards the end) where it seems that we do disagree, and it seems appropriate to explain that disagreement in this reply, although i don’t want the fact that we disagree on a very subtle and complex issue to obscure the fact that i do find the central argument of his paper an important contribution. The subtle issue in question has to do with supervenience. White sets up a complicated pair of examples. “in the first example,” White tells us, “one is in perceptual contact with the external world in the usual way. one has, however, a duplicate in a virtual reality setup whose brain is molecule-for-molecule identical to one’s own and is receiving the same electrical inputs. suppose that in the duplicate’s case the inputs are all completely artificial, and the duplicate is out of touch with the external world. in the second example, the source of the electrical inputs to one’s own brain switches back and forth (seamlessly) between the real world and an artificial source. suppose it does so in such a way that one has no idea that such switches are taking place. and suppose that when one is told about the switches, one has no idea when or how often they occur.” and he continues: