Determine which evidence strengthens or weakens an argument or interpretation.
Core Idea
Evaluate whether a piece of evidence makes an argument more or less convincing.
Understanding
Some Command of Evidence questions flip the usual task: instead of finding support, you need to find evidence that weakens an argument. This means looking for a fact that creates a problem for the claim — an exception, an alternative explanation, or a contradictory finding.
Pay close attention to the question's direction. "Strengthen" and "weaken" require opposite answers. Students lose easy points by reading too fast and picking a strengthener when the question asks for a weakener.
To weaken a claim, look for evidence that introduces a competing explanation, shows the claim doesn't hold in certain conditions, or directly contradicts a key assumption. To strengthen, look for evidence that confirms a prediction the claim makes or rules out an alternative.
Step by Step
- Determine whether the question asks you to strengthen or weaken the argument.
- Identify the argument's core claim and its key assumptions.
- For weakening: look for choices that offer alternative explanations, exceptions, or contradictions.
- For strengthening: look for choices that confirm the claim's predictions or rule out alternatives.
- Eliminate choices that are neutral or point in the wrong direction.
Misconceptions
- Mixing up strengthen and weaken — reading the question too quickly and picking evidence that does the opposite of what's asked.
- Thinking evidence must completely disprove a claim to weaken it. Even a partial exception or alternative explanation counts.
- Choosing evidence that's surprising or counterintuitive but doesn't actually affect the argument's logic.
Worked Example
Marine biologists have proposed that coral bleaching events in the Pacific Ocean are primarily driven by rising sea surface temperatures. A research team measured water temperatures and coral health across 40 reef sites over a five-year period and found a strong correlation between temperature spikes above 1.5°C beyond the seasonal average and subsequent bleaching events.
Which finding, if true, would most weaken the researchers' conclusion that rising temperatures are the primary driver of coral bleaching?
Select an answer to see the explanation