Most LSAT prep programs focus on question types in their treatment of the logical reasoning section. Another important, but less utilized, method of maximizing one’s score in the logical reasoning section is by identifying and understanding common argument structures.
The LSAT tends to recycle a few argument structures to create arguments that are used for all question types. This post will focus on analogy arguments — the second of three common argument structures — and how to attack these questions.
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Analogy arguments tell you that two things are similar, and that because one of those things has a certain characteristic, the other thing must as well. Let’s look at two examples:
1. LeBron James lifts weights, and his lifting weights causes him to become stronger. Therefore, if I lift weights, I will become stronger as well.
2. LeBron James lifts weights, and his lifting weights enables him to have a vertical leap of 40 inches. Therefore, if I lift weights, I will have a vertical leap of 40 inches as well.
Even though the first argument sounds more plausible than the second argument — there is little chance that I will ever achieve a 40-inch vertical leap — they both are missing the same thing: an explicit statement that indicates that LeBron James and I are similar in all relevant respects.
This is the key for all analogy arguments. In order for an analogy argument to work, you need to know that the two things being compared are similar in all the ways that they would need to be in order for us to know that we can make the jump from one thing to the other.
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So, in order to make these arguments valid, there would need to be information about the similarities between LeBron James and the subject of the question. For the first argument, you could add a statement that indicates that you are both human beings, and all human beings respond similarly to weight training.
The second argument is more difficult because it’s more specific. The conclusion is not just that you will get stronger, but that you will have a world-class vertical leap. If your intuition is the same as mine, this argument isn’t convincing.
This is because it seems to require not only that you will improve, but that your potential maximum vertical leap is the same as his. In other words, the reason the second argument doesn’t work is that you and he are not similar in respect to your potential maximum vertical leaps.
Once you have correctly identified an argument as having an analogy structure, what you are looking for in an answer choice will depend on the question that you are being asked. Analogy arguments come up most frequently in necessary assumption, sufficient assumption and flaw questions. Here is what you should look for in an answer for each of those question types.
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Flaw: The correct answer to flaw questions pertaining to analogy arguments usually indicates that the argument fails to consider something that shows that the two things being compared are not similar in some important respect.
For the second example above, a good flaw answer might be, “The argument fails to consider the possibility that LeBron James and I do not have the same vertical leap potential.”
Necessary assumption: For necessary assumption questions, look for an answer choice that tells you that the two things being compared are similar in at least one relevant respect that hasn’t already been mentioned in the argument.
For the first example above, a good necessary assumption answer might be, “All humans have the same cellular structure in their muscles, which affects how muscles respond to weight training.”
Sufficient assumption: For sufficient assumption questions, look for an answer choice that tells you that the two things being compared are similar in all relevant respects. For the first example above, a good sufficient assumption answer might be, “All humans respond similarly to weight training.”
Compare this answer to the sample answer for necessary assumption above, and note that the necessary assumption answer gives us one way in which you two are similar — same cellular structure in your muscles — whereas the sufficient assumption answer tells us that you and he are similar in all relevant respects, thus making the argument a valid argument.
What do you find most challenging about the logical reasoning section? Let me know in an email or tweet me.
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Untangle Analogy Arguments on the LSAT originally appeared on usnews.com
