Final answer:
Edgar's duel with Edmund in King Lear is justified within the narrative as a means to achieve justice and retribution. Edgar's actions contribute to the play's exploration of these themes by addressing the wrongs committed by Edmund and reflecting on the consequences of immoral actions.
Step-by-step explanation:
The justification for Edgar challenging Edmund to a duel in King Lear is anchored in the themes of justice and retribution. Edgar, the legitimate son, has been wronged by Edmund, the illegitimate brother, who has engaged in deception and treachery to usurp Edgar's position and inheritance. The duel becomes Edgar’s means of upholding justice and exacting retribution for both his father’s suffering and his own. The theme of retribution is also explored in the play through characters like Gloucester, who experiences harsh punishment for his own sins, and through the tragic structure of the play, which often sees characters meet their end as a form of recompense for their actions.
In the context of the play, the duel and Edmund's death serve as a culmination of the moral and ethical struggles between characters, and ultimately, the duel contributes to the broader narrative concerning the natural order and moral rectitude being restored after a period of chaos and injustice.