WeakenDiff: Easy
Logic Breakdown
Passage Summary: Lying makes your heart race, so machines that measure heart rates are perfect for catching liars.
Conclusion: Lie-detector tests are a foolproof method for identifying when a person is being untruthful.
Reasoning: Because the effort of lying triggers measurable physical changes like an increased heart rate, machines that detect these changes can accurately identify lies.
Analysis: This argument suffers from a classic 'correlation vs. causation' flaw. It assumes that because lying causes a fast heartbeat, a fast heartbeat must mean someone is lying. Look for an answer choice that suggests other things—like nerves, caffeine, or the stress of the test itself—could trigger the same physical reactions, making the 'sure way' claim far from certain.
Conclusion: Lie-detector tests are a foolproof method for identifying when a person is being untruthful.
Reasoning: Because the effort of lying triggers measurable physical changes like an increased heart rate, machines that detect these changes can accurately identify lies.
Analysis: This argument suffers from a classic 'correlation vs. causation' flaw. It assumes that because lying causes a fast heartbeat, a fast heartbeat must mean someone is lying. Look for an answer choice that suggests other things—like nerves, caffeine, or the stress of the test itself—could trigger the same physical reactions, making the 'sure way' claim far from certain.
Passage Stimulus
Passage Redacted
Unlock Full Passage1.Which one of the following statements, if true, most seriously weakens the argument?
Correct Answer
D
D shows that even truthful people can exhibit identical physiological reactions simply from the stress of the test. That means the presence of those reactions does not uniquely indicate lying, so lie-detector tests are not a “sure way” to determine lies.
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