There are different kinds of irony. For example:
Tragic (or dramatic) irony occurs when a character on stage or in a story is ignorant, but the audience watching knows his or her eventual fate, as in Shakespeare’s play Romeo and Juliet.
Socratic irony takes place when someone (classically a teacher) pretends to be foolish or ignorant, to expose the ignorance of another (and the teaching-audience, but not the student-victim, realizes the teacher's plot).
Cosmic irony is when a higher being or force interferes in a character's life, creating ironic settings.
H. W. Fowler, in Modern English Usage, says of irony:
Irony is a form of utterance that postulates a double audience, consisting of one party that hearing shall hear & shall not understand, & another party that, when more is meant than meets the ear, is aware both of that more & of the outsiders’ incomprehension.[1]
Irony threatens authoritative models of discourse by "removing the semantic security of ‘one signifier : one signified’";[2][3] irony has some of its foundation in the onlooker’s perception of paradox which arises from insoluble problems. For example, in June 2005, the State of Virginia Employment Agency, which handles unemployment compensation, announced that they would lay off 400 employees for lack of work, because unemployment was so low in the state. Although this outcome could have been logically anticipated (solving the problem would be expected to re-created a minor version of it again, as a result), the reader’s perception of a disconnection between common expectation, and the application of logic in an unexpected outcome, both contain an element of irony.
The connection between irony and humour is somewhat revealed when the surprise at what should have expected startles us into laughter. However, not all irony is humorous: “grim irony” and “stark irony” are familiar.
The Greek word eironeia—ειρωνεία applied particularly to understatement in the nature of dissimulation. Such irony occurred especially and notably in the assumed ignorance which Socrates adopted as a method of dialectic, the “Socratic irony.” Socratic irony involves a profession of ignorance that disguises a skeptical, non-committed attitude towards some dogma or universal opinion that lacks a basis in reason or in logic. Socrates’ “innocent” inquiries expose step by step the vanity or illogicality of the proposition by unsettling the assumptions of his dialogue partner by questioning or simply not sharing his basic assumptions. The irony entertains those onlookers who know that Socrates is wiser than he permits himself to appear and who may perceive slightly in advance the direction the “naïve” questioning will take. Fowler describes it:
The two parties in his audience were, first, the dogmatist, moved by pity and contempt to enlighten this ignorance, and, secondly, those who knew their Socrates and set themselves to watch the familiar game in which learning should be turned inside out by simplicity.
Many[citation needed] have interpreted Socrates as not feigning ignorance so much as expressing a form of philosophical skepticism.
Television journalist Louis Theroux demonstrated expert use of Socratic irony to his audience, by interviewing a number of diverse individuals with an air of relaxed naïveté and appreciative curiosity. This has led to his subjects becoming less guarded and more open in answering questions than they would have been in a more adversarial dialogue, while more often than not also granting Theroux subtle control of the interview.
The main character of Lieutenant Columbo, played by Peter Falk in the 1980's television sitcom Columbo employed the method of Socratic-irony to comic effect. The character's bad posture, piddling behavior, one squinted eye, and constant barrage of seemingly obvious questions were usually taken by criminals to be signs of utter incompetence, even mental disability. Ultimately, he was of course a brilliant crime solver. The slyness of his approach was often heightened by the fact that the clues had been apparent to the viewer as well. His signature line was "Um, excuse me, just one more question ma'am (or sir)..." which usually was followed by the realization by the culprit that they had been caught.
In his character of Ali G, Sacha Baron Cohen uses Socratic irony to satirical effect. For instance, in one sketch he interviews a professor from the National Poison Information Centre about recreational drug use. Ali’s pretended stupidity in the form of asking questions such as “Does Class A drugs absolutely guarantee that they is [sic] better quality?” elicits a response that makes drugs look like any other consumer article.
The 19th century Danish philosopher Søren Kierkegaard admired Socratic irony and used a variation of Socratic irony in many of his works. Kierkegaard wrote on Socratic irony in his master’s thesis, titled On the Concept of Irony with Continual Reference to Socrates. In the thesis, Kierkegaard praises Plato’s and Aristophanes’ use of Socratic irony, and argues that Aristophanes’ portrayal of Socrates in The Clouds most accurately captured the spirit of Socratic irony.