Argument Parts and Indicators
To understand LSAT Logical Reasoning questions, you must understand how an argument functions. Here’s what you need to know about arguments and how to evaluate them.
An argument consists of one or more premises and a conclusion. A premise is a fact, or piece of evidence, that the author uses to support a conclusion. A conclusion is a claim or statement that the author supports with at least one premise. Without both these parts, all you’ve got is a claim or a set of facts.
The Passage Isn’t Always an Argument
Some LSAT logical reasoning passages aren’t arguments at all. They may instead consist of a set of facts or principles with no conclusion. If the author isn’t trying to prove or convince you of anything, it’s not an argument.
A premise is a fact, or piece of evidence, that the author uses to support a conclusion.
An indicator word such as because, since, or for often comes before a premise. In the examples below, the premise is italicized and the indicator emboldened:
1) The world is getting warmer because atmospheric CO₂ is increasing.
2) Because atmospheric CO₂ is increasing, the world is getting warmer.
In both cases, the conclusion is nearby. Whether the conclusion comes before or after the word “because” is just a matter of style. The order doesn’t change the fact that “because” comes right before the premise.
There are two types of conclusions: main conclusions and intermediate conclusions.
Although you must accept premises as true on the LSAT, conclusions are open to debate. If an argument asserts as a premise that the world is flat, you must assume that’s true for the sake of argument. If it’s asserted as an intermediate conclusion or as the main conclusion, however, you can disagree.
The main conclusion is the point that the author is ultimately trying to prove. If an argument has only one conclusion, then that’s the main conclusion. If it has two or more conclusions, then the main conclusion is the one that is supported by any other conclusions in the argument. The main conclusion doesn’t have to be last; it can appear anywhere in the argument.
An intermediate conclusion is a conclusion that supports the main conclusion. Think of it as a stepping stone on the way to the author’s main conclusion. It’s a conclusion because it’s supported by at least one premise. It also acts as a premise, because it supports the main conclusion. When a statement serves both these functions, the LSAT calls it an “intermediate conclusion.”
Consider the following example:
Obama is smart (premise), so he will make good book recommendations (intermediate conclusion). Therefore, you should follow him on Instagram (main conclusion).
Although you have to accept Obama’s smartness as a fact, you can object to the argument in at least two ways: (1) Who says that being smart is all it takes to make good book recommendations? (2) Who says that you should follow on Instagram everyone who makes good book recommendations?
An indicator word such as therefore, thus, or so often comes before a conclusion. In these two examples, the premises are italicized and the conclusions are emboldened:
George is always late, so he’ll probably be fired.
Frogs are dying all around the world. Thus, we must act now.
The words therefore, thus, and so by themselves don’t necessarily introduce the main conclusion. You must look to other clues in the argument to decide whether the conclusion they introduce is the main conclusion or an intermediate conclusion. Ask yourself: Is this the main, overarching point the author is trying to argue, or is the author trying to convince me of this in order to prove something else?
What if There Are No Indicators?
Indicators are a good starting point for understanding how arguments work. Once you get comfortable, however, you should know how to identify argument parts based solely on the information in the argument. Some difficult Logical Reasoning questions have no indicator words.
Consider the following argument:
Evidently, we should care about climate change; frogs keep dying everywhere.
Can you figure out what the author’s conclusion is? Ask yourself: What is the author trying to convince me of? What is the author trying to sell me?
In this case, the author is trying to convince you that “we should care about climate change.” The reason is that “frogs keep dying everywhere.” Once you understand how the argument functions, you can start spotting gaps in it: How do we know that frogs dying is evidence of climate change? Why should we care about frogs dying? Remember, don’t argue with the premises, but attack the conclusion.
Other Argument Parts
Sometimes the author will introduce information into the passage that is neither a premise nor a conclusion. These “other” parts are often background information that provides context for the argument while not contributing directly to its logic.
Opinions and How to Spot Them
The phrases “many scientists argue that,” “most scholars agree that,” and “it is assumed that” (and other formulations of the same idea) all introduce the opinions of other people. In most arguments on the LSAT, when the author cites an opinion of others, it’s a prelude to an argument for why that opinion is wrong in some way.
In this example, the opinion is italicized:
Dr. Gingrich claims that we should create a colony on the moon. But this is a bad idea because, in this economy, we don’t have the resources to fund it.
The opinion, which belongs to Dr. Gingrich, is that we should create a colony on the moon. The author disagrees with this opinion. Test yourself: Can you spot the premise and the conclusion in the argument above?
Concessions and How to Spot Them
Indicators such as although, even though, and despite almost always introduce concessions.
In this example, the concession is italicized:
Although a few senators like Newt’s plan, his plan won’t be adopted by NASA. It’s already planning to go to Mars, and it doesn’t have the funding to do both.
The author is conceding that some senators like the plan that the author believes will ultimately not be adopted. Test yourself: What is/are the author’s premise(s), and what is the author’s conclusion?