Among students and colleagues I’m known for defending Putnam’s brain in a vat argument against all comers, be it incredulous stares or heated objections. Although I’m still a big fan of it, I have come to the conclusion that scepticism can escape it after all. (Some may think that was obvious all along. Alas, for me that is a new insight.) I started writing the paper with the intention to explain why sceptical scenario must not mess with memory, but couldn’t find a convincing reason to ban memory-alteration from sceptical scenarios. Unfortunately, Putnam’s argument is powerless against recent memory-altering envatment. After some tweaking of this scenario, I ended up with a scenario that is sufficiently radical for a successful sceptical argument, or so it seems to me. – As always comments are very welcome! But please don’t cite without asking for the latest version.
Keywords: Cartesian scepticism · Putnam · brains in a vat · constraints on sceptical scenarios · scepticism and content externalism · memory
Abstract: Putnam’s argument that we are not brains in a vat has recently seen a resurgence in interest. Although objections to it are legion, an emerging consensus seems to be that even if it successfully refutes one version of the scenario, lifelong envatment, it is powerless against the recent envatment version of the scenario. Although initially appealing, this strategy generates problems of its own. In this paper I argue that merely switching to recent envatment is indeed a bad response to Putnam’s argument, yet there is a different version, recent memory-altering envatment, that Putnam’s argument does not refute and is also sufficiently radical. The crucial issue turns out to be which epistemic sources sceptical scenarios may attack. It is argued that there is no convincing reason for exempting memory from the sceptical attack. Putnam’s argument does not fail because of some ‘deep’ philosophical mistake, but because it overlooks how flexible and adjustable sceptical scenarios are.