Final answer:
Rev. Parris accuses John Proctor of plotting against the court when he arrives with Mary Warren. Parris's accusation is influenced by the fear of losing his standing and the threat to the Salem witch trials' legitimacy.
Step-by-step explanation:
When John Proctor arrives at court with Mary Warren in Arthur Miller's The Crucible, Rev. Parris accuses him of plotting against the court. Parris suggests that Proctor's efforts to defend his wife and discredit the court's proceedings are part of a larger scheme to undermine the court's authority. This accusation is made within the tense atmosphere of Salem, where fears of witchcraft and the devil's influence run high, spurring a series of tragic events resulting from mass hysteria and false accusations. The main explanation for Parris's accusation lies in his fear of losing his standing in the community and the threat he feels from Proctor's challenge to the legitimacy of the witch trials.