The two most important types of logic on the LSAT are conditional and causal reasoning.
Conditional reasoning may be phrased in various ways, but it can be essentially reduced to if-then statements. For example: “If you are a lawyer, then you must have passed the bar exam.”
If-then statements lead to powerful deductions. Every if-then statement has a valid contrapositive, such as: “If you did not pass the bar exam, you must not be a lawyer.”
Many logical reasoning questions require test-takers to deduce what must be true or could be true based on these conditional statements. For example, given the above statements, is it true that anyone who passed the bar exam must be a lawyer?
Not necessarily. Just because everyone who is a lawyer passed the bar exam does not mean that everyone who passed the bar exam is a lawyer. This is an example of flawed reasoning.
Mastering conditional reasoning takes work. Because it is so powerful and pivotal on the LSAT, however, many test-takers neglect other kinds of logic, particularly causal reasoning.
[Read: What the LSAT Is and How to Prepare]
What Is Causal Reasoning?
Causal reasoning appears frequently in the reading comprehension and logical reasoning sections. Rather than if-then, it is composed of cause-effect statements. Examples include:
— I feel sick because I ate too much pasta.
— Law school applications increase during economic downturns because more people are looking to change jobs.
Causal reasoning is critically important in law, science, social science, history and everyday life. If the LSAT gives you a causal argument, it may ask you to find a flaw in it, find evidence relevant to the validity of the argument, identify ways to strengthen the argument or compare the argument to other similar arguments.
However, the LSAT will not ask you to draw inferences from causal arguments because unlike conditional arguments, they cannot be used to make logically valid deductions.
[Read: Weighing LSAT Test Prep Options]
Identifying Causal Reasoning on the LSAT
A causal argument has two parts: a cause and an effect. The cause must occur before the effect. Before you dismiss this point as obvious, note that it is not necessarily true in conditional reasoning. Take the above conditional statement: “If you are a lawyer, then you must have passed the bar exam.” This is saying that if you are a lawyer, then you must have taken a bar exam in the past. It is not a causal argument.
While the cause must precede the effect in time, the order of the statement itself is irrelevant. Often the effect comes before the cause in a sentence, as in: “I feel sick because I ate too much pasta.” Here, the cause is eating too much pasta and the effect is feeling sick.
When in doubt, look for words associated with cause and effect. It helps that there are not many ways to describe causal logic in the English language. Look for phrases like: “because of,” “contributed to,” “due to,” “responsible for,” “led to” and “produced by.”
Answering LSAT Causal Reasoning Questions
Once you have identified causal reasoning in a logical reasoning question or in a reading comprehension passage, your work is not over. It is easier, however.
Single out the cause and effect in the argument. Look for supporting evidence. Then determine what the question is asking you to do to the argument. Often, your task is to strengthen, weaken or evaluate the argument based on the evidence presented.
[Read: What Is a Good LSAT Score?]
To weaken a causal argument, see if it mistakes correlation for causation. Just because you ate pasta and feel sick does not mean the pasta caused the illness. Perhaps something else is responsible, like the milkshake you drank or a stomach bug you caught.
You might also look for reasons to question the data used to support the causal argument. For example, if I make an argument about what causes law school applications to increase during economic downturns, how am I determining what counts as an economic downturn? Am I looking at the right time frame for the application cycle?
To strengthen a causal argument, shore up the relationship between cause and effect. If everyone else who ate the pasta got sick, then the pasta was more likely the culprit. If medical tests ruled out a virus, then the case seems even more solid.
Remember that it is not necessary to prove the causal argument conclusively. No causal argument can be completely certain, which is why the findings of fields like history and science can change over time as new evidence comes to light.
Likewise, while causal reasoning causes you some frustrations at first, with practice it may become one of the sharpest arrows in your quiver.
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Causal Reasoning on the LSAT: What to Know originally appeared on usnews.com
Update 03/17/25: This article was published at an earlier date and has been updated with new information.
