Affirmative and Negative are the two sides in American debate formats like Policy (Cross-Examination), Lincoln-Douglas, and Public Forum. The Affirmative team, often called Aff, argues in favor of the resolution. The Negative team, often called Neg, argues against it. The terms are used the same way Proposition and Opposition are in parliamentary formats.
Burden of Proof on the Aff
In American policy formats, the Affirmative has the burden of proof - they must prove that the resolution should be adopted. The Negative does not need to prove the current policy is perfect; they just need to show that the Affirmative did not meet the burden of proof. This asymmetry shapes the entire strategy of both sides.
Aff and Neg Strategies
Affirmative cases usually include a plan (a specific policy proposal), advantages (benefits of the plan), and defenses against common objections. Negative strategies typically involve disadvantages, counterplans, kritiks, or procedural arguments like topicality (claiming the Aff plan does not actually meet the resolution).