Though the novel’s titular Catch-22 is a specific military clause about mental illness and military service, the same essential concept recurs through numerous bureaucratic and legal paradoxes that trap characters and remove their control over their own destiny. Catch-22s often appear as a method of control to prevent characters from acting freely. The first use of the phrase, for example, is when Doc Daneeka explains to Yossarian that a psychiatric diagnosis won’t ground him from flying missions: Anyone who wants to excuse evade the dangerous missions is, by definition, “sane” as no rational person would want to subject themselves to such danger. Moreover, the doctor explains, the demonstrably “insane” people (like Orr) can only be declared such by telling the doctor—and, in doing so, they will be demonstrating their own “sanity.” Such a diagnosis thus can never excuse men from missions, as the paradoxical legal system places them in logical trap.

The Catch-22 becomes a recurring motif. Whenever characters encounter some kind of legal paradox that denies them agency, they instinctively refer to Catch-22. Yossarian begins to preemptively refer to the paradox when he encounters whatever bureaucratic rule is forcing him to fly another mission or remain in the military.