Watson-Glaser Inference Questions: The Prior Knowledge You Need Before You Start

A tough set of questions in the Watson-Glaser Critical Thinking Appraisal is the inference question. You are given a passage, followed by a statement that draws an inference from the passage. You are then asked to judge whether the inference is true, probably true, false, probably false, or whether there is insufficient data to say.

Before you can answer an inference question effectively, there are two concepts you need to be very clear about. The first concept is what an inference is. The second is the two kinds of argument that are featured commonly in the Watson-Glaser. In this post, I look at both, and at why Watson-Glaser test prep for the inference question needs an understanding of logical reasoning.

What is an inference?

You make inferences all the time from the data in front of you or the evidence you see. But you never think of it as making an inference. Here are two favourites of mine:

• You see heavy clouds in the sky, and you infer that it is likely to rain.
• You see a lot of people waiting outside a restaurant, and you infer that the food at the restaurant must be good.

In each case, you move from the evidence to a conclusion. To put it simply, an inference takes this form: reason 1, reason 2, and then a conclusion drawn from them.

In case you have forgotten, an argument is a conclusion supported by reasons. So an inference set out in this way is an argument. This is why, to answer inference questions, you need to understand arguments.

The first kind of argument: deductive arguments

One set of questions in the Watson-Glaser is based on deductive arguments. The definition of a deductive argument is that if the reasons are true, the conclusion must be true. Here are three types of deductive argument:

If you look at each of these arguments, you will see that if the reasons are true, the conclusion has to be true. If human beings are indeed mortal, and Socrates is a human being, there is no other inference you can draw except that Socrates is also mortal.

Also, if it is true that the ground will be wet if it rains, and it is raining, then there is no alternative but to draw the conclusion that the ground will be wet.

Of course, in all these arguments, one thing you assume is that the statements, as stated, are true. You do not bring in your own thinking and say, "The ground may not be wet because they will cover it with a tarpaulin," or "The ground may not be wet because it has a roof over it." In the Watson-Glaser test, when you are given a set of statements, you simply accept them as true, and draw your inferences based on them.

The second kind of argument: inductive arguments

Now look at the other type of argument, which is also very common. In an inductive argument, if the reasons are true, the conclusion is likely to be true. Here is an example:

There is a very important difference between this argument and the earlier arguments. Even if the incentives are good, you cannot be certain that the sales teams will be highly motivated and will deliver good sales. There may be other reasons why the sales teams are not well motivated.

Let's look at another argument, and this idea will probably become clearer.

This is a very reasonable conclusion to draw. But you can never be 100% sure that every Harvard student is very intelligent. There is always the probability that someone did well on all the tests and interviews used for admission but is not very intelligent. Wilson could be that person.

There are several different types of inductive arguments, and there is a system for evaluating these arguments. The book Critical Thinking for Watson-Glaser covers all the different types of reasoning and how to evaluate these arguments.

Coming back to the inference question

The inference question gives you a passage, makes an inference from the statements in the passage, and then asks you to judge whether the inference is:

• True
• Probably True
• Insufficient Data
• Probably False
• False

True and False are largely arrived at by deduction, that is, by reasoning deductively from the statements given. Even so, the reasoning behind an inference can come from either a deductive or an inductive argument. Deciding whether an inference is Probably True or Probably False, or whether there is Insufficient Data, can be done only by evaluating the argument. That means understanding what an argument is, what the different types of arguments are, and how to evaluate them.

Watson-Glaser test prep: why logical reasoning is essential

This is why, for Watson-Glaser test prep, learning the concepts of logical reasoning is essential. Without these concepts, you judge an inference by whether it "sounds" true. With them, you can tell which kind of argument you are looking at and how the conclusion follows from the passage. You also need causal reasoning, because many passages describe one thing causing another.

All of these concepts are covered in the book Critical Thinking for Watson-Glaser. The book also gives you 168 Watson-Glaser practice questions with detailed answers, and the answers show which concepts apply to each question.

You can take a closer look at the inference question, and how to answer it, in this article: How to answer Watson-Glaser inference questions.