Flawed ReasoningDiff: Easy
Logic Breakdown
Passage Summary: A professor thinks that because some students liked a lecture, they must have been there from the start, since being there from the start makes you like it.
Conclusion: Some students must have heard the lecture from the beginning.
Reasoning: Hearing the lecture from the start guarantees finding it fascinating, and some students did find it fascinating.
Analysis: The professor is committing the formal fallacy of affirming the consequent. Just because 'A (starting early) leads to B (fascination)' doesn't mean that 'B' can only be caused by 'A.' Perhaps the lecture was so good that even students who arrived halfway through were captivated. To find the flaw, look for an answer that points out the possibility of the result occurring without the specific sufficient condition mentioned.
Conclusion: Some students must have heard the lecture from the beginning.
Reasoning: Hearing the lecture from the start guarantees finding it fascinating, and some students did find it fascinating.
Analysis: The professor is committing the formal fallacy of affirming the consequent. Just because 'A (starting early) leads to B (fascination)' doesn't mean that 'B' can only be caused by 'A.' Perhaps the lecture was so good that even students who arrived halfway through were captivated. To find the flaw, look for an answer that points out the possibility of the result occurring without the specific sufficient condition mentioned.
Passage Stimulus
Passage Redacted
Unlock Full Passage21.The conclusion of Professor O'Brien's argument does not follow logically from its premises because of the possibility that
Correct Answer
D
It makes possible that no one who both heard the lecture from the beginning and found it fascinating was one of O’Brien’s students. That directly blocks the inference from “some of my students found it fascinating” to “some of my students heard it from the beginning.”
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