I think I said this before, but I can’t find it:

Sarcasm is what we do when another shirks their ironic duty, and we do their irony for them by stating their own beliefs with an ironic nonirony.

This notion of ironic duty is based on Richard Rorty’s understanding of irony’s role in liberal-democratic politics:

An ironist is someone who fulfills three conditions: (1) She has radical and continuing doubts about the final vocabulary she currently uses, because she has been impressed by other vocabularies; (2) She realizes that argument phrased in her present vocabulary can neither underwrite nor dissolve these doubts; (3) Insofar as she philosophizes about her situation, she does not think that her vocabulary is closer to reality than others, that it is in touch with a power not herself.