I wonder how many of those "some economists" there really are. I know that, e.g., Paul Krugman, one of Cochrane's leading ideological opponents, vigorously denies that all models, data and experience say fiscal stimulus doesn't work.

My point was not to argue about fiscal stimulus. Indeed, if you deny that the models, data, etc, say that, then that is an intellectually respectable position, same as with any scientific dispute. But what is definitely not respectable, what is below the sanity waterline, is the attitude in the quote - that science says X, but I don't believe it anyway.

And that is very widespread, in my experience.