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Conclusion = Evidence + Assumption

or

Conclusion − Evidence = Assumption

The ability to understand simple but formal argument structure is useful, if not essential, to advance critical thinking. After identifying the conclusion and evidence, we then proceed to examine the third element, called the assumption. So how do we go about identifying the first two elements, the conclusion and evidence?

Identifying the Conclusion and Evidence

Confusion may arise as to what part of an argument is evidence and what part is the conclusion. Certain "guide words" always signal the use of evidence or the start of the conclusion. The chart on the next page lists the most common guide words. If, for example, you hear someone say, “Because the economy is getting better, I’m going to buy a car,” you may presume that the phrase “because the economy is getting better” is evidence. The reason for this is that “because” always signals the use of evidence. The remaining phrase “I’m going to buy a car” contains the conclusion. Note that these phrases may also be reversed without affecting what is the evidence and conclusion. For example, “I’m going to buy a car because the economy is getting better.”

If possible, use guide words to identify the conclusion and evidence in an argument.

It is important to note that guide words will not always be present to guide you, meaning that you cannot always rely on them to locate the conclusion and the evidence in an argument.

Locating the Assumption

Whereas the conclusion and evidence in an argument are always explicit, the assumption is always implicit. The fact that assumptions are by definition implicit means that they will not be stated, that is, written down on paper or spoken out loud by the speaker. They exist foremost in the mind of the author or speaker. Conclusions and evidence, on the other hand, are explicit. This means that they will be stated — physically written down on paper or spoken out loud.

EVALUATING ARGUMENTS

Tip #21: There are effectively two ways to attack an argument: attack the evidence or the assumption(s).

In seeking to evaluate arguments, we must aggressively analyze each component. How strong is the evidence? How strong is the key assumption? Obviously, in order to attack the evidence and the assumption, we must be able to identify them.

Short exercises: To practice using classic argument structure to evaluate arguments, fill in the missing pieces below — conclusion, evidence, and assumption. Proposed solutions follow below.

1. Dorothy and her College Entrance Exam

Argument: As Dorothy achieved a high score on her college entrance exam, she will surely succeed in college.

Conclusion:

Evidence:

Assumption:

2. Finland

Argument: Finland is the most technologically advanced country in the world. More people per capita own mobile phones in Finland than anywhere else on earth.

Conclusion:

Evidence:

Assumption:

3. Taking on the World with a Smile

Argument: Dear Anita: You know, I get such a great feeling when I talk to my old high school friends and find out they’re doing well. Just yesterday, I spoke with Paul and Maxine and have been in a good mood ever since. Say, I hear you’re kind of down in the dumps lately. If you go home and call your high school friends, it will cheer you up and you will be ready to take on the world with a smile. Talk to you soon, Bill.

Conclusion:

Evidence:

Assumption:

4. Quick-Stop vs. Big-Buy Grocery Stores

Argument: I shop at Big-Buy grocery stores because prices are 10% less than at Quick-Stop grocery stores.

Conclusion:

Evidence:

Assumption:

1. Dorothy and her College Entrance Exam (Solution)

Argument: As Dorothy achieved a high score on her college entrance exam, she will surely succeed in college.

Conclusion: Dorothy will surely succeed in college.

Evidence: She achieved a high score on her college entrance exam.

Assumption: Success on a college entrance