Contradictory Premises
Contradictory premises are two claims in one argument that cannot both be true, so nothing can be concluded from them. Debaters point to the two premises, show the conflict, and explain that the argument collapses.
Contradictory Premises as it appears in championship debate rounds. Each example below is a moment from a real round, with a note on why it illustrates the technique and how a debater can use it, or answer it.
Example 1: The questioner exposes a tension in the negative's position
Congress supposedly says yes to legalizing marijuana inside the strategy, yet adding the plan alongside a strategy on other issues supposedly makes Congress say no. Laying the two premises side by side ('how does that not prove no?') forces the respondent into a vague bright-line answer. Use this cross-ex move whenever an opponent's solvency claim and their deficit to your permutation rely on incompatible assumptions about the same actor.
Example 2: In cross-examination, the questioner presses the opponent on two positions that clash
The opponent claims disclosing information is bad because it screws over some people, which the questioner labels a consequentialist argument. Yet the same debater also argued that consequences don't matter and that consequentialism should be rejected. The questioner is exposing contradictory premises within one case. Use cross-ex this way: get the opponent to commit to the second claim on record, then name the conflict in your next speech.
Example 3: The judge identifies a fundamental tension in the affirmative case
It claims China will model good US anti-suit behavior, yet also insists China is an untrustworthy revisionist that will always cheat. Both premises cannot hold together, and the judge says the negative should have exploited this contradiction. Students should audit their own advantages for premises that undercut each other, and look for this contradiction when opponents run both modeling and threat scenarios.
Example 4: In a rebuttal speech, the speaker extends the contradiction from cross-ex
The opponents argued both that ASEAN cannot solve and that the plan fractures ASEAN, so they have 'massively double-turned themselves on this page.' This exposes contradictory premises in the opposing case. Students can call out a double turn explicitly and ask the judge to let them keep whichever half of the contradiction helps their side.
Example 5: The affirmative points out that the advantage counterplan's planks contradict each other: they both ban and regulate offsets
The speaker argues the negative must 'make up their mind' and that the affirmative gets new answers once the negative picks a plank. Exposing contradictory premises inside a multi-plank counterplan forces the opponent to drop part of their advocacy. It also justifies extra answers later in the round.
Example 6: A judge points out that the affirmative's two claims cannot both hold
Their topicality defense says Article 51 already makes anticipatory defense a current commitment. Yet their plan claims that citing Article 51 reduces that commitment. If the plan relies on the very source of the commitment, it cannot shrink it, so the plan may not solve. Debaters should check that their topicality defense and their solvency story rest on compatible premises; opponents can exploit this kind of contradiction.
Sources: every example links to the YouTube video of the championship debate it comes from, at the moment described.
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