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Weakening and Strengthening on the LSAT

A common LSAT question type asks you to weaken or strengthen an argument. The LSAT is an excellent predictor or your success in law school. If you learn to think like the test requires, you’ll also learn skills that will help you get better grades. So it makes sense that the LSAT would ask you to weaken and strengthen arguments, since you’ll be spending a lot of time doing that in law school.

This is the first in a series of articles on Weakening and Strengthening questions on the LSAT Test. The series includes the following articles:

Weakening and Strengthening on the LSAT

By asking you to weaken or strengthen an argument, the LSAT is testing you on several levels all at the same time. First, you have to understand the main point of an argument. That’s a task you would be asked in a conclusion question. Second, the flaw of an argument usually centers on the central assumption. So you have to identify that assumption to attack it or shore it up against attack. That’s a task you would be asked by an assumption question. Finally, you have to find the answer that actually weakens or strengthens the argument. In a way, the LSAT is asking you three questions at the same time.

Don’t worry, though, these are actually easy questions. Skilled TestSherpa students are so adept at recognizing flawed assumption that the right answer choices practically beg to be marked. As you practice, you will learn all the traps that the wrong answers offer as well. A high score on the LSAT depends on a lot of practice. Each test is used to compare candidates from the last five years. The test can’t change too much, so the more sample questions you practice and study, the better prepared you will be.

As you’ve already seen in the lesson on assumptions, the weakest link in an argument is the central assumption. You are not allowed to question the premises—you have to accept them as true in order to evaluate an argument. You may, however, freely question the assumptions an author makes.

In real life, you might have time to question premises. You could look up the facts an argument is based on and prove that the argument is wrong. The LSAT is different. You don’t need any outside knowledge to take the LSAT. Besides, you can’t possibly know everything in the world anyway, so it would be rare that you could ever easily argue about someone’s premises.

To attack assumptions you only need to understand the logic behind them. You just have to understand how they bridge the gap between the premises and the conclusions. It’s all there for you in the argument. That is why when the LSAT asks you to weaken or strengthen an argument; it is usually asking you to attack or support the central assumption.

Think of an argument as a table with three legs: the premises, conclusion, and assumptions. The assumption is the weakest leg. If you want to weaken the argument, kick at the assumption and hope the table falls down. If you want to strengthen the argument, strengthen the assumption so that when your opponents start kicking at your table, it will stay standing.

The weakest part of an argument is the assumption – look to attack or support it. The next weakest leg is the conclusion. Obviously, if you can contradict the conclusion you seriously weaken the argument. The problem is, this technique is so obvious the LSAT does not spend a lot of time testing your ability to do it. One or two out of every ten weaken or strengthen questions might deal with the conclusion. The rest deal with the assumption.

Also remember to look for red flags. Red flags are your intuitive reaction to problems with the logic of an argument. Most arguments on the LSAT contain flawed central assumptions. When you read them, a red flag should pop up, pointing you toward that weakness. If you want to weaken the argument, you will find an answer choice that emphasizes that red flag, or weakness.

Conversely, if you want to strengthen an argument—and a bad one at that—you should try to hide the red flag. An answer choice that denies the red flag, or fills in the gap of reasoning that a flawed assumption represents, strengthens an argument significantly.

Next let’s look at some Strengthen LSAT Questions.