The idea that we may be brains in vats is commonly used in philosophy courses as a way of talking about Cartesian skepticism. Maybe all of our experiences are simulated inputs created by some mad scientist in the “real” reality. This idea has more recently been the basic premise of The Matrix.

In a recent podcast, Sam Harris noted that we are, in fact, brains in vats. Or, to phrase it more carefully, even taking as true the non-skeptical viewpoint in which our experiences are veridical rather than simulated input, we are still brains in vats. The vats are just rather small and hard, usually called “skulls”.

The idea that reality may be something entirely beyond our actual experiences is more mysterious than we give it credit for. I might similarly imagine that, when I use the name “Gregory”, while I may think I mean a particular balding friend who lives in Farmington, I actually mean a minor metaphysical poet who will be born some millenia hence in the Sombrero Galaxy. Whatever we may make of our experiences, if our words can so thoroughly betray us our doubts should go much further than Descartes’.