“Humorist” is a profoundly dismal word, for it does not signify any deep and genuine humor so much as humorism, that profession of forced amusement around which true laughter can rarely hope to survive. Hear it and you’re likely to think of New Yorker exclamation points, Garrison Keillor columns, the nasal monotone of some refugee on npr talking about growing up in America. Comic, comedian, jester, wit—even a clown is better than a humorist.

So it should come as no surprise that of the fourteen people Paul Johnson chose to write about in Humorists, only two, James Thurber and Damon Runyan, ever had to contend with the label. Hogarth, Thomas Rowlandson, and Toulouse-Lautrec were satirical painters and caricaturists. Laurel and Hardy, Charlie Chaplin, W. C. Fields, and the Marx Brothers were masterful performers. Noël Coward’s finest work (Brief Encounter, in my view) wasn’t even...