Agreed to differ.

The phrase signals a deliberate truce in argument: two parties recognize that further debate is unlikely to produce agreement, so they choose to end the dispute without hostility. As a compact formula, it implies both intellectual humility (accepting that one’s view may not prevail) and social tact (preserving civility and relationship over winning). If attributed to Southey, it also fits the period’s epistolary and conversational culture, where disagreements—political, religious, or literary—were often managed through polite closure rather than open rupture. The expression has since become a standard idiom for respectful disagreement.