Innerlogics

An MIT linguistics professor was lecturing his class the other day. “In English,” he said, “a double negative forms a positive. However, in some languages, such as Russian, a double negative remains a negative. But there isn’t a single language, not one, in which a double positive can express a negative.”

A voice from the back of the room piped up, “Yeah, right.”

From Is “double positive meaning negative” a common phenomenon? on the Linguistics StackExchange:

Yes, for example, it’s the same in Italian “sì, sì” (= yes, yes), but it’s ambiguous, it depends on intonation and not on the words themselves; this means that “double positive = negative” is wrong speaking about the words, but it works through other means. Changing intonation, that “sì, sì” can be absolutely positive as well. We also use a small variation in written language to substitute the intonation. We write “seh seh” or “se se”… More or less like the English slang variation “ye ye”.

And more about Sarcasm in The Lousy Linguist:

There are 3 interpretations of “yeah, right” in American English:

1. Normal (factual agreement): yeah right = ‘yes, that is correct’
2. Sarcastic (opposite meaning): yeah right = ‘no way in hell’
3. Back-channel (sentiment agreement): yeah right = ‘mm-hmm’

Thanks to the influence of Seinfeld and Friends throughout the 90s, Sarcastic is probably the default use these days…