[xanderlewis]

I agree. It is surprising the degree to which they seem to be able to generalise, though I'd say in my experience the generalisation is very much at the syntax level and doesn't really reflect an underlying 'understanding' of what's being represented by the text — just a very, very good model of what text that represents reality tends to look like.

The commenter below is right that the amount of data involved is ridiculously massive, so I don't think human intuition is well equipped to have a sense of how much these models have seen before.