CARS Lesson 11  —  Implied premises and warrants
The missing pieces to the puzzle

You don't have to be a superhuman reader to get a great score on CARS. Your unconscious intuition is more powerful than you may credit. At times when you're reading, you will have a sixth sense that the writer hasn't closed the circle. Something is missing in the argument. The writer is taking something for granted. They may seem to expect you to take it for granted. You don't have to. It's good to have a bit of a framework to resolve what may be going on. Are the authors premises sound? Is their evidence actually warranted?

We're supposed to get to the end of these passages in four or five minutes. It's impossible to turn over every stone. It's unnatural to expect it! How are we supposed to read these essays at the pace of speech; form a mental image of the structure of the essay; determine the main idea; and also investigate the essay for implied premises and warrants while we're reading? You do your best. That's the answer. Pausing or backing up in a passage every now and then is doing it right, but, even then, you are always moving forward with a sense of flow, engagement, and zero stress.

Remember that the question-writer has taken a lot longer with the passage than four or five minutes. They have hours and hours to write the questions. It's unfair to expect yourself to have seen everything in the passage they will have seen, but still you try. You try to see all the way to the bottom all the time.

In every kind of communication, the audience is routinely called upon to help construct the meaning. Premises are often unstated, or the warrant for evidence may be implied. Reading closely from a critical perspective examines unstated premises in deductive argument. In deductive logic, a conclusion is sound only if the premises are sound.

In inductive argument, you read closely to make sure evidence is warranted. Does the evidence have strong connection to the claims it is being used to justify? For justification by inference from evidence, the conclusion is sound only if the evidence is warranted.

When you get down to brass tacks, this particular lesson is about keeping you out of trouble with particular kinds of CARS questions. The question-writer will have mined the passage for unstated premises and implied warrants. They are looking for the raw materials for making a question. The particular type of specific inference question dealing with an unstated premise may seem really subtle. You may not have noticed the implication in the passage, but you are primed to see what the test-writer is up to. Questions like this become much easier if you have a little background. Let's talk about unstated premises and implied warrants.

A logical argument with a missing premise is called an enthymeme
  • What is a syllogism?

    Let's start with the simplest kind of deductive, logical argument, the syllogism. A syllogism is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two or more premises. In deductive logic, the premises are propositions which are asserted or assumed to be true. In a syllogism, a conclusion is deduced from the combination of a general statement, called the major premise, and a specific statement, which is called the minor premise. For example, if we know that all people are mortal (major premise) and that Socrates is a person (minor premise), we can conclude with 100% certainty that Socrates is mortal. As long as the major and minor premises are both true, the conclusion must be true. Syllogistic arguments are usually represented in three lines:

    All people are mortal.
    Socrates is a person.
    Therefore, Socrates is mortal.
  • An enthymeme is a truncated syllogism

    A syllogism with an unstated premise is an enthymeme. Here are some examples with the implied premise in italics.

    Socrates is mortal because he's a person. (All people are mortal.)

    Rosemary lied to me last week, so she can’t be trusted. (Liars can’t be trusted.)

    You'll be successful. Just follow your passion! (All people who follow their passions are successful.)

    I can't believe Bill scammed you. I've known him for years! (No friend of mine is untrustworthy.)

    Senator Simmons wants to increase regulation. He's a socialist! (Anyone who wants to increase regulation is a socialist.)

    In its logical structure, an enthymeme asserts the truth of a statement the author hasn't explicitly said. The conclusion depends on it. The author implies the unstated premise. A typical CARS question may ask you to supply the missing premise. You may not have picked it up in the reading, but these questions are not too hard if you see what the question-writer is up to. Alternatively a question may ask you to judge the effect on the author's argument, hypothetically, if the missing premise were NOT true.

Implied warrants
  • Inference from evidence

    We discussed enthymemes above. An enthymeme is a truncated syllogism. A syllogism is a form of deductive reasoning. With deduction, as long as the premises are true and the logic sound, the conclusion is true. Deductive reasoning relies on formal logic. Many, if not most, everyday examples of reasoning and justification, however, don't rely on formal logic but informal logic. Informal logic governs the truth value of inferences we make based on evidence. An inference is not a kind of deductive reasoning. Inferring the truth of a claim based on the evidence is reasoning from experience. With inductive reasoning, you can't achieve absolute certainty. However, if something is almost certainly true, that is reasonable grounds to believe it! Scientific theories are based on inductive reasoning.

  • The warrant is the connection between a claim and evidence

    We discussed the structure of Toulmin argument in lesson 6. Toulmin identified three main parts to any argument. The first part of any argument is the claim (also called thesis or proposition). The second is the evidence (also called grounds or data). The third essential part of any argument is the warrant. The warrant is the connection between the claim and the evidence supporting it. How is this evidence relevant to the claim? How strong is the support provided by the evidence? That depends on the strength of the warrant. Let's look at a simple argument as an example:

    Jonathan must be ill, since he has a cough.

    The claim is "Jonathan is ill". The evidence in support of this claim is, "Jonathan has a cough." Where's the warrant? The warrant here is not explicit. More often than not, the warrant for evidence will be implied. The warrant here might be expressed, "A cough is a sign of illness." In this simple, obvious example, you can see how Toulmin provides a basic, general framework for analyzing the likelihood of the truth of a claim. Making the warrant explicit is how we interrogate the strength of the evidence. You can never be absolutely certain with inductive logic, but likelihood of truth is reasonable justification for belief. Suppose we learned that 95% of the time, in clinical presentation, a cough is a sign of illness. This would support the warrant for the evidence (if Jonathan were in a clinic). Support for the strength of a warrant is called its backing.

    In the CARS section of the exam, you are likely to run into a specific inference question dealing with an implied warrant for evidence. A question may ask you to supply the warrant, ie. the author assumes that . . .. Alternatively, a question may ask you to judge the effect on the author's claim if the strength of the warrant were undermined. These types of questions are very similar to those that might arise from an enthymeme. As a matter of fact, in the Rhetoric, almost 2500 years ago, Aristotle presented a very similar framework as Toulmin's three-part framework of claim, evidence and warrant. Aristotle called this three part figure a syllogism based on signs. Signs are things so closely related that the presence or absence of one indicates the presence or absence of the other.

    Since Rosemary arrived on foot, she must not have a car.

    In this syllogism based on signs, the missing premise is the statement, "Only a person without a car would walk on foot." This isn't a deductive syllogism, though. The claim may or may not be true depending on the warrant. Maybe Rosemary owns a car but likes to walk?

Summing it up

Being alert to recognize unstated premises or implied warrants is a valuable skill for reading critically. Teach yourself to ask, "Is there an unstated premise here?" or "Is this evidence warranted?". This skill can be helpful when you sense a weakness. You can quickly analyze the weakness in a specific claim by excavating its underlying assumptions. When that happens in a CARS passage, it's a good chance you will have anticipated a question, because the test-writer likely sensed the same weakness. The more you can make it manifest during the process of reading, the better off you'll be, but don't hold yourself to an impossible standard. Maintain flow, immersion, and engagement. You may not have spotted the enthymeme when you read the passage. That's only natural. But when the question comes later, you know what the test-writer is getting at, and the question will not be difficult.

Let's practice

Continue working through Step 2 and Step 3 of the CARS Diagnostic Tool. Pace yourself to complete the curriculum provided by this resource within the next three modules.

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