Impact Calculus
To conclude the debate, the rebuttalist speakers should do what’s called impact calculus: comparing the impacts of the two teams’ arguments and demonstrating to the judge why their own impacts outweigh those of the other team. There are four possible facets through which to perform impact calculus. As a rebuttalist, you must analyze magnitude and probability; however, timeframe and reversibility are optional. If you can prove that your team wins on each type of impact, then you win the debate. Below are more details for each category.
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Magnitude
Magnitude describes how large an impact is in terms of its quantitative (how many people are affected) and qualitative (how much these people are affected) significance. All else equal, a judge should weigh an impact with greater magnitude more heavily.
For example, you could argue that the benefits from a higher minimum wage for low-income individuals outweigh the potential decrease in economic growth in terms of magnitude
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Probability
Probability describes how likely an impact is to occur. Although some impacts may have great magnitude, they are unlikely to manifest, which decreases their probability.
For example, you could state that United States military support for Ukraine would have a high probability of successfully curtailing Russia’s invasion while nuclear war due to American intervention, though potentially catastrophic, is highly unlikely due to mutually assured destruction.
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Timeframe
Timeframe describes how far into the future an impact will occur. Since circumstances can change in the future, a judge should weigh an imminent impact more heavily than one that occurs in the distant future.
For example, you could contend that the negative impacts of free trade outweigh the positive impacts since the loss of jobs in industry is immediate while the increased economic activity due to greater efficiency occurs further along in the future.
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Reversibility
Reversibility describes whether or not an impact is permanent. Irreversible impacts carry greater weight in debate.
For example, you could state that governments should restrict civil liberties during wartime for the sake of national security since lives lost due to espionage are irreversible while civil liberties can be restored in peacetime.