The Truth, the whole Truth, and… Lying on the LSAT
While working through a particularly difficult slew of questions with my lovely class the other night, I noticed a few things. First, nothing gets a crowd pumped like a discussion of fractal geometry. Second, and more pertinent to our discussion here, students have a hard time knowing when they should question the truth of different claims made on the LSAT.
After some spirited discussion intertwined with some personal insults, we came around to one big distinction. There are facts, and then there is everything else.
When the conclusion of a Logical Reasoning question relies on a fact, there is no reason to doubt the accuracy of this claim. Here are some fascinating LSAT examples.
The male sage grouse inflates its air sacs as part of the spring courtship ritual.
Failed electric resistance is known to be a factor in the phenomenon called “ball lightning.”
When scientists shone a bright light into the tank, the snail tensed its muscular foot.
Anything that lowers blood cholesterol levels lowers the risk of hardening of the arteries due to arterial blockage.
Remember, the LSAT is not testing your ability to ascertain the truth of these claims. (I’ve never met a sage grouse or examined an air sac either). That means that any problems in the argument will be found in the relationship between different claims. You can assume all of these premises are true and focus on why they are not sufficient to prove the truth of the conclusion.
A different problem arises when an argument relies on any other type of claim. Tina has herpes. Stated as such, this is a verified fact (and you should probably steer clear, regardless of what those creepy Valtrex commercials say). But if Theo, a jilted ex-lover, told someone that Tina has herpes, is that reliable? Possibly not. When an argument relies on claims that people have made, stories that have been reported, widespread beliefs, poll results, or anything similar, you have to question whether such claims are actually true.
The following are claims found in recent LSAT questions. Noting the vulnerability of each of these claims was crucial to finding the correct answer.
A newspaper claims that public safety will be enhanced if new weather sirens are installed.
The mortality rate of cases of CXC reported by farmers has increased in the past five years.
If the data reported in a recent study are correct, moderate exercise lowers blood cholesterol levels.
Sometimes one reads a poem and believes that it expresses contradictory ideas.
As soon as you read such claims, your thoughts should immediately revolve around the issues raised by these claims. Is the newspaper correct? Are the farmers reporting representative cases? Are the results of the study correct? If people believe it’s there, is the contradiction really there?
If you are doing a Flaw question, the fallacy will be tied to the suspicious nature of these claims. If you have to strengthen, weaken, or identify an assumption, the correct answer will either affirm or question the validity of these claims.
One additional twist has popped up recently. Relying on the truth of such claims raises questions, but occasionally an argument will fix this mistake. Take the following argument.
The bank robbery occurred at three o’clock in the afternoon. Devers testified that McDevitt was present at a lengthy board meeting downtown that did not adjourn until four o’clock on the same afternoon. Thus, if Devers is testifying truthfully, McDevitt is not the masked man that was caught on camera during the bank robbery.
The first premise is a fact. The bank robbery occurred at three o’clock. The second premise, however, raises some questions because it is based on the testimony of Devers. What if Devers is in on it and lying? However, the conclusion is qualified to only follow if Devers is testifying truthfully. Without this qualification, it would be a flaw to assume that Devers was telling the truth.
Always beware what type of evidence is presented. A fact is a fact. But anything else can help you quickly find a correct answer.