The opposite of irony is common sense. For that is the watchword of those who unselfconsciously describe everything important in terms of the final vocabulary to which they and those around them are habituated. To be common-sensical is to take for granted that statements formulated in that final vocabulary suffice to describe and judge the beliefs, actions and lives of those who employ alternative final vocabularies.

The ironist, by contrast, is a nominalist and a historicist; She thinks nothing has an intrinsic nature, a real essence. So she thinks that the occurrence of a term like "just" or "scientific" or "rational" in the final vocabulary of the day is no reason to think that Socratic inquiry into the essence of justice or science or rationality will take one much beyond the language games of one's time. The ironist spends her time worrying about the possibility that she has been initiated into the wrong tribe, taught to play the wrong language game.

She worries that the process of socialization which turned her into a human being by giving her a language may have given her the wrong language, and so turned her into the wrong kind of human being. But she cannot give a criterion of wrongness. So, the more she is driven to articulate her situation in philosophical terms, the more she reminds hetself of her rootlessness by constantly using terms like "Weltanschauung," "perspective," "dialectic, conceptual framework," "historical epoch," "language game," "redescription, "vocabulary," and "irony.

from Private Irony and Liberal Hope , by Richard Rorty