LSAT 12 - Section 4 - Question 08

This question stem is a little unusual. If you struggled to identify this as a Necessary Assumption question, think about the conditional function of the “unless.” The answer choice is the condition following the “unless,” so we could negate sufficient to say something like, “If which one of the follow answers is not assumed, then the conclusion cited does not follow.” If we contrapose this, we get, “If the conclusion cited follows, then which answer must be assumed?” This puts the answer choice in the necessary condition of the conditional. So, we know this is a necessary assumption question.

We see that there are a number of inconsistencies in a history book. From this, these scholars conclude that the author must have been drawing from multiple sources.

And that’s it. That’s the whole stimulus. This is a very simple argument: Inconsistencies, therefore multiple sources. Structurally, this is just “A therefore B.” These are very common LSAT arguments, and they have never done the work of tying the relevancy of the premise to the conclusion. And they always fail as arguments for this reason. Does the premise have anything to do with the conclusion? These arguments do not establish that connection. One assumption always necessary for these is “If A then B.” It isn’t a very interesting assumption, but it is necessary. Here, that is “If inconsistencies then multiple sources used.” Notice this is also sufficient. That can cause some alarm, but do not fear. With this particular argument structure, such an assumption will be both sufficient and necessary. They don’t have to give us this exactly, so we will still keep an open mind in the answers, but these arguments are so simplistic, they do not create much opportunity for alternatives.

Answer Choice (A) We don’t care about what authors “generally” do. Maybe they generally ignore discrepancies. Or maybe they generally convey the discrepancies and discuss the reason for the discrepancies with commentary on the likely reliability of their different sources. Who cares what they generally do or why? Not us. We care about what this one particular author actually did on this one particular occasion. Any given generality is welcome to be true, but need not be. If it doesn’t have to be true, it isn’t necessary.

Answer Choice (B) Again, this is just not something we care about. The average reader is welcome to spot these inconsistencies. They are equally welcome to overlook them. We care about the number of sources the author used, and the reader simply has nothing to do with that.

Correct Answer Choice (C) A and B tried to tell us something that does happen. This is telling us something that did not: The author did not use a single source which itself contained the inconsistencies in our author’s book. This has to be true. This is the right answer. If our author did use one source which itself contained the same inconsistencies as the book in question, then these inconsistencies need not result from inconsistencies among multiple sources. It seems quite reasonable that the inconsistencies could have resulted from the same inconsistencies from this one source.

Answer Choice (D) This is wrong for similar reasons as A and B. We do not care one way or the other if our author was aware that inconsistencies could arise. With our without their awareness, the inconsistencies arose. That’s all that really matters here. Their awareness has no bearing on the source of the inconsistencies.

Answer Choice (E) This is wrong for the exact same reason as everything else. In D, the author’s awareness of the possibility of inconsistencies doesn’t matter. Here, the author’s awareness of all the possible source materials doesn’t matter. If there was one book relevant to the subject that they didn’t know about, does that mean anything for our argument relating to the source of the inconsistencies? It does not.