PrepTest 114, Section 2, Question 5
Logician: I have studied and thoroughly mastered the(32 more words not shown)
The reasoning in the logician's(6 more words not shown)
- Aignores the fact(9 more words not shown)
- Bpresents no evidence(9 more words not shown)
- Cfails to rule(15 more words not shown)
- Dtreats two kinds(13 more words not shown)
- Ehas a conclusion(8 more words not shown)
Reading the argument
Knowing the rules doesn't make it impossible to reason badly.
The logician compares a mistake in conversation with a physicist doing something outside the laws of physics. But those are different kinds of “laws.” Logic gives us standards for correct reasoning. A person can know a standard and fail to follow it in a hurried conversation. Physical laws describe how the physical world works; a physicist doesn't become exempt from them by misunderstanding or ignoring them.
So I'll grant that the logician has studied the subject thoroughly. That doesn't make every argument the logician gives flawless. In fact, this comparison needs defending: why should mastery of rules we can fail to follow work like living in a world whose physical laws govern what happens?
What we’re looking for
For the flaw, I'd look for a comparison that overlooks that important difference. We need to question whether the physicist's situation tells us anything useful about the logician's claimed immunity to mistakes.
Working the answers
- A
Our understanding of physical laws can change. That doesn't mean a physicist can step outside the actual laws governing the world. The problem with the comparison is the difference between those laws and standards for reasoning, not whether our scientific descriptions are complete.
- B
Difficulty of learning and reliability of performance are different issues. Even if physics and logic were equally difficult to master, the logician could still make a reasoning mistake. Comparing how hard the subjects are wouldn't repair the difference that makes this analogy fail.
- C
We don't need an example of a physicist breaking a physical law to challenge this argument. Grant that the physicist cannot do that. It still doesn't follow that the logician cannot reason incorrectly, because logical standards can be violated. C focuses on overturning the wrong side of the comparison.
- DCorrect
The two kinds of laws differ in the respect that matters to the argument. Physical laws govern what actually happens in the physical world. Logical rules describe how reasoning should work, and people can fail to follow them even when they know them.
The logician treats those situations as equivalent, then uses that supposed equivalence to reject the possibility of an ordinary reasoning error. The important difference means the comparison doesn't establish that conclusion.
- E
A contradiction would require the conclusion and premise to be unable to hold together. “I've mastered logic” and “I don't violate its rules in conversation” don't contradict each other. The first simply hasn't established the second through this comparison. An unsupported conclusion is different from a conclusion that conflicts with its premise.
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