Abstract

It’s pretty standard to find pretty compelling the claim that for all one can tell one may be a vat‐brain: not least, to say the least, because it’s a version of Descartes’ demon thought‐experiment in the First Meditation. Here I refute that claim. Like Descartes I start with the idea that one has an undeniable grip on most of what one is thinking. To this I add the idea that knowing thinking as thinking is being able to engage in it. Then I argue that one can’t engage in the (purported) thinking of a vat‐brain (there are various specimens of vat‐brain to be considered). The essential point is that one cannot make anything of what a vat‐brain’s intended ontology would be, and how the brain might conceive of it. So one cannot engage with any vat‐brain’s (purported) thinking. Yet one engages with one’s own. So one isn’t any of them. I’m not, anyway: you can speak for yourself.