4. Identifying Premises and Conclusions

Argument analysis would be a lot easier if people gave their arguments in standard form, with the premises and conclusions flagged in an obvious way.

But people don’t usually talk this way, or write this way. Sometimes the conclusion of an argument is obvious, but sometimes it’s not. Sometimes the conclusion is buried or implicit and we have to reconstruct the argument based on what’s given, and it’s not always obvious how to do this.

In this lecture we’re going to look at some principles that will help us identify premises and conclusions and put natural language arguments in standard form. This is a very important critical thinking skill.

Here’s an argument:

“Abortion is wrong because all human life is sacred.”

Question: which is the conclusion?

“Abortion is wrong”?

“All human life is sacred”?

For most of us the answer is clear. “Abortion is wrong” is the conclusion, and “All human life is sacred” is the premise.

How did we know this? Well, two things are going on.

First, we’re consciously, intentionally, reading for the argument, and when we do this we’re asking ourselves, “what claim are we being asked to believe or accept, and what other claims are being offered as reasons to accept that claim?”.

Second, we recognize the logical significance of the word “because”. “Because” is what we call an indicator word, a word that indicates the logical relationship of claims that come before it or after it. In this case it indicates that the claim following it is being offered as a reason to accept the claim before it.

So, rewriting this argument in standard form, it looks like this ...

1. All human life is sacred.
Therefore, abortion is wrong.

At this point we could start talking about whether this is a good argument or not, but that’s not really our concern right now. Right now we’re more concerned with identifying premises and conclusions and getting the logical structure of an argument right.

Here are some key words or phrases that indicate a CONCLUSION:

therefore, so, hence, thus, it follows that, as a result, consequently,

and of course there are others.

This argument gives an example using “so”:

It’s flu season and you work with kids, SO you should get a flu shot.

Now, keywords like these make it much easier to identify conclusions, but not all arguments have keywords that flag the conclusion. Some arguments have no indicator words of any kind. In these cases you have to rely on your ability to analyze context and read for the argument.

Here’s a more complex argument that illustrates this point:

"We must reduce the amount of money we spend on space exploration. Right now, the enemy is launching a massive military buildup, and we need the additional money to purchase military equipment to match the anticipated increase in the enemy’s strength."

Notice that there are no indicator words that might help us flag the conclusion.

So, which claim is the conclusion of this argument?

Is it ...

“We must reduce the amount of money we spend on space exploration.”?

Is it ...

“The enemy is launching a massive military buildup”?

Or is it ...

“We need the additional money to purchase military equipment to match the anticipated increase in the enemy’s strength”?

The answer is ...

“We must reduce the amount of money we spend on space exploration.”

Most people can see this just by looking at the argument for a few seconds, but from experience I know that some people have a harder time seeing logical relationships like this.

If it’s not obvious, the way to work the problem is this: for each claim asserted in the argument you have to ask yourself,

“Is this the main point that the arguer is trying to convey?”

or,

“Is this a claim that is being offered as a reason to believe another claim?”

If it’s being offered as a reason to believe another claim, then it’s functioning as a premise. If it’s expressing the main point of the argument, what the argument is trying to persuade you to accept, then it’s the conclusion.

There are words and phrases that indicate premises too. Here are a few:

since, if, because, from which it follows, for these reasons,

and of course there are others.

And here’s an example that uses “since”:

"John will probably receive the next promotion SINCE he’s been here the longest."

“Since” is used to indicate that John’s being here the longest is a reason for thinking that he will probably receive the next promotion.

So, let’s summarize:

Arguments in natural language aren’t usually presented in standard form, so we need to know how to extract the logical structure from the language that’s given.
To do this, we look at each of the claims in the argument and we ask ourselves, is this the main point that the arguer is trying to convey, or is this being offered as a reason to accept some other claim?
The claim that expresses the main point is the conclusion.
The claims that are functioning as reasons to accept the main point are the premises.
And finally, premises and conclusions are often flagged by the presence of indicator words. Paying attention to indicator words can really help to simplify the task of reconstructing an argument.