I am teaching 17th&18th Century Philosophy this semester for the first time in a while. This week was my favorite bit of the course: Berkeley’s argument for idealism.
It’s a short, deductively valid argument from tempting premises, to the conclusion that the whole sensible world is just ideas. It invites a kind of wonder at how thoughts can fit together.
After we covered it, one student asked if we would be reading anyone who opposed this. With Descartes, they said, it was easy to see what was wrong with the arguments. But this just had them boggled.
This is akin to my student years ago who said, “This can’t be right. I don’t know what’s wrong with it, but something has to be.” Does something have to be wrong with it, though? It’s the natural culmination of the theory of ideas, a framing assumption of philosophy in the period.