Poetic Justice is defined as the ideal distribution of rewards, but many times in literature it tends to be an ironic twist of fate that delivers an intellectual punch. Such is the case in "The Lady, or the Tiger?" The king is described as having "barbaric idealism." As a result, he creates an extreme justice system that is based on chance, but is also believed by the king to be his ideal distribution of rewards, or poetic justice.
A criminal is given a choice between two doors; behind one is a reward and freedom, and behind the other is a fatal consequence such as a hungry tiger. The philosophy behind the arena is described as follows:
"The institution was a very popular one. When the people gathered together on one of the great trial days, they never knew whether they were to witness a bloody slaughter or a hilarious wedding. The element of uncertainty lent an interest to the occasion which it could not otherwise have attained. Thus, the masses were entertained and pleased, and the thinking part of the community could bring no charge of unfairness against this plan; for did not the accused person have the whole matter in his own hands?"
The above passage explains the thinking behind the functioning of the arena, as well as the justification for its alleged equitable treatment of justice. The problem with the arena is that it is maintained and controlled by a barbaric king. The arena is only used when the king sees fit, so it seems to represent a fair play by chance for the accused, but the execution of justice is solely in the hands of the king.