As most all movements in any art form are, the Theatre of the Absurd was a reaction both to dramatic forms and theatrical conventions that had come before it and also a reaction to the events on the world stage. For Theatre of the Absurd, these events concerned life post World War II, during which time many began to question the meaning of life. Here's a good summary, from the Entoes Study Guide:
Absurdist drama arose from the spiritual and physical devastation of World War II, prompted by the existentialism of Jean-Paul Sartre and Albert Camus. In Europe, such early proponents as Eugène Ionesco, Samuel Beckett, Jean Genet, and Harold Pinter sought to unshackle themselves from the realistic thesis play that had dominated serious theater from Henrik Ibsen’s day forward by creating a new form of drama more suited to a world viewed as being devoid of purpose, legitimate moral authority, or even simple human dignity.
As for Pinter himself, his beginning work as a playwright coincided with the emergence of the Absurdist movement in theatre in the 1950's and 60's. Though his works, on the surface, seem to have a realistic tone, beneath the surface he is questioning the meaning of life. Most significantly, however, he is examining the way man expresses himself through language, taking his "natural" presentation of speech patterns to such extreme that, onstage, they appear absurd and even comical. Here's what Enotes has to say about Pinter's experimentation with language:
Pinter portrays the absurdity of human existence with a loving attention to detail that creates the deceptive naturalism of his surfaces. It is particularly with the meticulously rendered, tape-recorder-accurate language of his characters that Pinter pulls the naturalistic and absurdist strands of his drama all together. The language of his characters, bumbling, repetitive, circular, is actually more realistic—more like actual human speech—than the precise and rhetorically patterned dialogue found in what is considered to be “realistic” drama. Yet that actual language of human beings, when isolated on the stage, underlines the absurdity of human aspirations and becomes both wonderfully comic and pathetic as it marks the stages of human beings’ inability to communicate what is most important to them. What makes Pinter one of the most important modern British dramatists is his consummate skill as a dramatist; the fact that in language and pattern he is a poet.
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