The objective of today’s class is to learn how:

To evaluate the strength of an argument

Evaluating an Argument:

An argument offers reasons to believe that some statement is true.

When you evaluate an argument, you are deciding whether the reasons being given show or do not show that the statement, the conclusion, is true. And you must state a reason to support your decision on this issue.

When you evaluate an argument, you can make two kinds of criticisms of the argument.

uThe content of the premises of the argument can be criticized. This kind of evaluation is called a content criticism.

uThe relationship between the premises and the conclusion can be criticized. This kind of criticism is called a formal criticism.

Consider first content criticism:

To make a content criticism ask yourself whether there is an objection that you can raise about one of the reasons being given for the conclusion.

Now consider the following argument:

Developing a central surveillance system that registered every action of every citizen would be very beneficial.

This is because the behavior of robbers, sexual offenders, and murderers could be stopped in the midst of the crime.

With respect to the reason being given, one might criticize it as follows:

A content criticism of this argument might be as follows.

The reason given to support the conclusion assumes that police could get to the criminal in time to stop the crime. But this is not likely.

Next consider a formal criticism.

To make a formal criticism:

You must ask yourself whether the premise is appropriately related to the conclusion.

A premise is NOT appropriately related to the conclusion if one of the following conditions obtains:

1. The case mentioned in the premise is relevantly different from the case mention in the conclusion.

For example: We do not allow the sale of drugs on campus. So we should not allow the sale of soft drinks on campus.

2. The conclusion is about the future and the premise is about the past but background information makes the inference unlikely.

For example: Charlie Sheen has been a very bankable star in the past, so it is likely that he will continue to make lots of money in the future.

3. The case mentioned in the premise is a single case (or an unusual case) and the conclusion is about the majority (or all) cases (or is about the usual cases).

For example: A student who raised her hand to answer a question knew the answer to the question, so all of the students in the class knew the answer to the question.