PrepTest 105, Section 4, Question 8
Linguist: Only if a sentence can be diagrammed(35 more words not shown)
The linguist's reasoning is flawed(8 more words not shown)
- Amost people are(5 more words not shown)
- Bsome ungrammatical sentences(2 more words not shown)
- Call sentences recognized(5 more words not shown)
- Dall grammatical sentences(3 more words not shown)
- Esome ungrammatical sentences(4 more words not shown)
Reading the argument
Being able to diagram the sentence clears one requirement. It doesn't tell us the sentence is grammatical. The first rule says a grammatical sentence must be diagrammable. The second says that speakers recognize a grammatical sentence as grammatical. If we knew X's sentence was grammatical, that second rule would get us to the conclusion. But all we know is that it can be diagrammed. Perhaps a sentence can be diagrammed despite having a grammatical error.
What we’re looking for
That possibility is the flaw to look for. The author treats diagrammability as a guarantee of grammaticality even though the first rule only makes it a requirement. Without establishing the grammaticality step, the argument cannot use the recognition rule to finish the chain.
Working the answers
- A
We already know X's sentence can be diagrammed. Whether most people have the skill to do it doesn't tell us whether the sentence is grammatical. The relevant problem is the relationship between the sentence's properties, not the public's ability to produce diagrams.
- BCorrect
An ungrammatical sentence might still be diagrammable. Then X's sentence could meet the stated diagrammability requirement without being grammatical, and the rule about recognizing grammatical sentences would not establish the conclusion.
B does not have to prove that X's sentence is actually ungrammatical. It identifies the possibility the argument has failed to rule out. The premises tell us what a grammatical sentence must allow; they don't guarantee that every sentence allowing it is grammatical.
- C
This says recognition as grammatical requires diagrammability. We need to get from X's diagrammability to recognition, and C doesn't give us that direction. A sentence could be diagrammable without being recognized as grammatical even if C were true. So this isn't the overlooked possibility that exposes the missing step.
- D
This is the first premise in straightforward wording: all grammatical sentences can be diagrammed. Repeating that requirement doesn't show that X's sentence is grammatical merely because it meets the requirement. It leaves the same gap in place.
- E
Some ungrammatical sentences being correctly recognized as ungrammatical tells us nothing about whether those sentences are diagrammable. We need to connect the fact we know about X's sentence—its diagrammability—to the possibility that it isn't grammatical. E doesn't provide that connection.
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