This week’s post is the first in a series that will provide you with a complete overview of LSAT content and the basic skills you will need to perform your best on it. This first installment will discuss how to understand arguments in the logical reasoning section.
More than 75 percent of LSAT logical reasoning questions will contain an argument. For purposes of the LSAT, an argument is a conclusion supported by premises. In questions involving arguments, you will often see the LSAT refer to the “argument” or the “reasoning.” If you see either of these words in your question, you can be certain that you are dealing with an argument.
[Learn to navigate common LSAT logical reasoning mistakes.]
Identifying Premises and Conclusion
In order to understand an argument and ultimately answer the question associated with it, you must first identify the argument’s premises and conclusion.
The safest way to identify conclusions and premises is to use connecting words that indicate a statement’s role in the argument. These words can be broken into three categories: those that indicate conclusions, those that indicate premises and those that indicate statements that conflict with the argument.
Words and phrases that indicate conclusions include “so,” “therefore,” “as a result” and “thus.” Words that indicate premises include “because,” “since” and “for.” Words that indicate conflicting statements include “however,” “on the other hand,” “although” and “while.”
Remember that the order of the statements does not determine their function in the argument.
[Erase three top LSAT preparation myths.]
Common Flaw Types
In addition to containing a conclusion and premises, an LSAT argument will be either valid or invalid. A valid argument is one whose conclusion logically follows from the premises, while an invalid argument is one whose conclusion does not logically follow from the premises. The vast majority of arguments you will encounter on the LSAT will be invalid.
Determining the validity of an argument is rarely an issue on the LSAT. In fact, the question type or the wording of the question will usually indicate to you whether or not the argument is valid.
Much more important is determining why an argument is invalid — in other words, why an argument is flawed. Below are two of the most common types of flawed arguments on the LSAT.
The first type is a correlation or causation argument. In a correlation or causation flaw, the speaker concludes from the fact that two events or characteristics are correlated and occur at the same time or in succession. One of the two events or characteristics caused the other.
One example might be, “My research indicates that those who drink two or more cups of coffee per day are more likely to have insomnia than those who don’t. Therefore, drinking two or more cups of coffee per day causes insomnia.”
In this example, the speaker correlates drinking two or more cups of coffee with insomnia. The two tend to occur together. The speaker then concludes that the coffee drinking is the cause of the insomnia.
In fact, it is possible that the causation is reversed: Insomnia could cause someone to drink lots of coffee. There could be no causal relationship between the two whatsoever, or their correlation could be the result of a shared, underlying cause independent of both.
If you see a conclusion asserting a causal relationship, always check the premises to see whether the speaker has established more than a mere correlation to support his or her conclusion.
[Check out LSAT trends to know while preparing for upcoming tests.]
The second type is the unrepresentative sample. In an unrepresentative sample flaw, the speaker draws a conclusion about a larger group based on a sample of that group that we have no reason to believe is representative.
An example might be: “Since almost all my local friends are fans of jazz music, it must be true that most people who live here are fans of jazz music as well.”
Here, the speaker makes a conclusion about all people who live in the same city as the speaker based on a subset of that group that the speaker has not established as representative. The speaker could be a jazz musician, in which case it would be natural for his friends to share his interest in jazz to a much larger degree than the rest of the population.
When encountering a generalization about a larger group from a subset of that group, ask yourself what you know about the subset. For instance, is there anything that suggests that it is or is not representative of the larger population?
If there isn’t anything that suggests the subset is representative of the larger population , then the speaker has drawn a conclusion based on an unrepresentative sample.
More from U.S. News
Untangle Analogy Arguments on the LSAT
Study Effectively When Retaking the LSAT
Erase 3 Top LSAT Preparation Myths
Train to Recognize LSAT Logical Reasoning Arguments originally appeared on usnews.com
