Identifying Arguments and Statements

1. Indicator Words

In the last tutorial, we mentioned that logical arguments are made up of sequenced statements. Statements declare something. The statements can be subjective, false, or unproven as long as they claim something is true. However, we do not include questions, exclamations, or commands.

try it

Which of the following sentences are logical statements? Remember that a statement does not have to be true or even provable, as long as it asserts that something is true.

1. Alligators are on average larger than crocodiles.
2. Is an alligator a reptile or a mammal?
3. An alligator is either a reptile or a mammal.
4. Don’t let any reptiles into the house.
5. You should kill any reptile you see in the house.
6. Oh no! An alligator.

Check Your Work

Here are the answers you should have gotten.

1. Statement
2. Not a statement (question)
3. Statement
4. Not a statement (command)
5. Statement
6. Not a statement (exclamation)

However, determining whether a statement is declarative isn’t always that easy. Natural languages can be ambiguous or nuanced. For example, people can ask a question that implies something without saying it directly. If someone worriedly asks, “Did you cook this chicken to 165 degrees?”, they are definitely telling the cook, “You undercooked the chicken.” In logical interpretation of arguments, we can’t make such assumptions about what the speaker “really” meant. Understanding what is really a declarative statement and what is not is a bit trickier than it might seem. Throughout this tutorial, we’ll learn how to spot the statements in natural language and figure out which are the premises, which are the conclusions, and which are not actually part of the argument.

1a. Conclusion Indicators

Say you’ve found all the statements in a natural language argument and are ready to write it in standard form. Which statement is the conclusion? We tend to think of it as the last, the “therefore,” that caps off an argument, but in natural language it can be anywhere. Consider this argument.

It had to be the gardener or the butler. The butler has an alibi. So, the gardener must have done it.

This is one of the most conventional forms of argument: two or more premises that, when combined, lead us to a conclusion. However, a single sentence can contain a complete argument. Consider this example.

The butler has an alibi, so he cannot have done it.

This argument has one premise followed by a conclusion. Similarly, as we saw in Sally’s second argument with Bob, the conclusion can actually come first:

The butler didn’t do it. He has an alibi.

The conclusion can even come in the middle.

Either the gardener or the butler did it. The gardener must have done it, because the butler has an alibi.

So, you can’t use the placement of the statement to figure out which is the conclusion. You have to use good judgment to see which sentence reflects the gist of the entire argument. There are a number of words and phrases that can indicate the argument’s conclusion.

• so
• therefore
• hence
• thus
• accordingly
• consequently
• ergo
• it follows that

These are called conclusion indicator words. While it isn’t as simple as merely finding a sentence with one of these words, it is a good way to start focusing on sentences that seem to draw conclusions from other sentences.

term to know

Conclusion Indicator Words

Words in natural language that suggest the sentence in the argument is the conclusion, or main purpose, of the argument. Common examples include therefore, so, thus, and hence.

1b. Premise Indicators

There are also premise indicator words, words and phrases that suggest a sentence will lead to a conclusion. These words include:

• whereas
• since
• because
• given that
• firstly, secondly, etc.

There are many more, and it’s not a one hundred percent certainty that any of these words means that the sentence is a premise. For example, these are uses of “indicator words” which do not, here, function to indicate a premise or conclusion.

I have been running competitively since 1999.

I am so happy to have finally finished that class.

The only way to be sure is to read carefully and use good judgment.

try it

Which of the following statements is an argument? If it is an argument, what are the premises and what is the conclusion?

• The queen died, then the king died of sadness.
• The queen died, so the king died of sadness.
• I’m not surprised the king died, given what happened to the queen.

Check Your Answer

The first statement is not an argument, it is simply a chronicle of events. The second and third are arguments with the same premises (the queen died, which made the king sad) and the same conclusion (the king died of sadness). You may recognize the conclusion indicator, “so,” or the premise indicator, “given [that].”

term to know

Premise Indicator Words

Words in natural language that suggest the sentence in the argument is a premise, or reason to believe the conclusion. Common examples include whereas, since, and because.

1c. Statements That Aren’t Part of the Argument

In natural language arguments, we may also encounter factual statements that are not part of the argument. Consider this argument:

The bayou is home to a rich variety of wildlife, including herons, pelicans, muskrats, opossums, and more! The one creature you don’t want to see up close is an alligator. These big reptiles are a real threat to humans. They are quick to attack and eat anything, including pets and people.

If you were translating this into logical terms, you would omit the first sentence. It is a factual statement, but does not support the conclusion, which is to stay away from alligators. So, keep in mind that just because something is a statement, doesn’t mean it’s a premise or a conclusion.

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2. Identifying Arguments

Before we translate an argument into sentential logic, we also need to confirm whether it is even a logical argument. Let’s recap what we have learned so far.

A good logical argument is:

• At least two statements, including at least one premise and a conclusion. (Remember that two statements can appear in one sentence in natural language, linked by a word like “so” or “because.”)
• The conclusion is what is being argued for, and must be a statement of fact.
• The premises provide evidence, reasons, and grounds for the conclusion.
• The argument involves a process of reasoning from the truth of the premises to the truth of the conclusion.

Identifying a logical argument will involve determining if the first two conditions are met. Evaluating the argument (seeing if it is a good argument) will involve determining if the next two conditions are met. For now, we will focus on identifying logical arguments.

hint

When we say an argument isn’t logical, we don’t mean it is illogical, or unreasonable, simply that it uses other kinds of persuasion like evoking sympathy. Indeed, to be illogical (or failing at logic), an argument needs to be logical (in the sense that it is trying to use logical reasoning).

2a. Is It a Logical Argument?

The best way to identify whether a logical argument is present is to ask:

(a) whether there is a statement that someone is trying to establish as true, by...

(b) basing it on some other statement.

Consider this sentence. Is it a logical argument?

I’ve had the kids all day, so take them for tomorrow.

We have a premise that is a statement of fact: I’ve had the kids all day. But the next part is not a statement of fact, but a command. Thus, though it meets the broader definition of an argument, it is not the kind of argument you can translate into logical terms (at least not the way it is phrased).

If there had been a statement after ‘so’, meaning an assertion that something is true, then there would have been a logical argument present. If not, then there isn’t.

In the next example, the conclusion is phrased as a statement, an assertion that something is true (if subjective), so it could be written as a logical statement. But if the speaker states something without supporting premises, it is not an argument, simply a statement.

You have to take the kids tomorrow!

Moreover, suppose your spouse tries to convince you by listing all the fun things you did last week while they were stuck at home with the kids.

You went bowling on Monday, went out with coworkers on Tuesday, saw your brother on Wednesday, and holed up in your man cave last night, so I had the kids all week.

This is simply a chronicling of events, not an argument. It may be exactly what is needed to persuade you that you’ve been shirking your duties and gives your spouse a break, but it is not a logical argument—it’s an emotional one.

But suppose your spouse says:

I’ve had the kids all week and need a break. So, you should take them tomorrow.

Though the intent of this sentence is the same (to get the spouse to take the kids), this one explicitly makes an assertion and supports it with evidence, so it is a logical argument.

Note that there is an assumption in the above argument, which is that parents should share in parenting duties equally. An assumption like this does not make the argument invalid, as long as it is understood and agreed to by others. These are called hidden premises, and we will discuss them more later. They do not always make an argument invalid, but may hide premises that are false or misleading.

term to know

Hidden Premise

An unstated premise in an argument, usually based on a safe assumption or shared understanding.

2b. Normative Statements

A final question—why do ‘should’ sentences count as statements when imperatives do not? In other words, what’s the difference in logic between (a) and (b):

(a) You should do the dishes.

(b) Do the dishes!

The key lies in the grammar of English and other natural languages. Sentences constructed with words like ‘should’, ‘can’, or ‘must’ are still declarative sentences in grammatical terms. They don’t order somebody to do something, but make a statement of fact about what they should do. These are called normative arguments, or ones that state what one ought to do instead of what is already factually true. Normative statements can be contrasted with descriptive statements, which are simply factual claims about what is true.

EXAMPLE

“Alabama has the death penalty” is a descriptive statement. “Alabama should have the death penalty” is a normative statement.

We will look more at normative arguments later in this unit. For now, it is just important to distinguish between normative statements (which are allowed in logical arguments) and imperatives (which are not).

hint

A good way to determine if a statement is normative is to ask if you can tell what the person making the argument believes from the statement. For example, see the three statements below. Each seems to be arguing for an election day holiday, but only one is normative.

Statement	Normative?
People should have election day off so they can vote	Normative
Most people support an election day holiday	Not normative (declares a fact, it is unknown if the person making the argument is one of those people).
It is proven that countries with election day holidays have higher voter participation	Not normative, it is unknown if the person making the argument believes voter participation is good.

Normative arguments have their own indicator words like “should” and “ought,” or might have phrases like, “we have an obligation to,” or “it is imperative that.” These will appear in addition to the usual conclusion indicator words.

However, this does not affect the logical rules of the argument; the conclusion is still a declarative sentence that follows from the premises. Be careful here when determining what does and does not count as a statement.

try it

For each of the following conclusions, determine if the argument is normative or descriptive. Remember that in a normative statement you can tell what the speaker believes.

Downloading movies without paying is illegal.

This is a descriptive statement. The speaker may or may not agree with the laws.

Lots of people download movies from pirate sites and most of them will not get caught.

This is a descriptive statement. The speaker may or may not think the people doing this are in the wrong.

Downloading movies takes money from the creators.

This is a descriptive statement. While it suggests the speaker disapproves of downloading movies illegally, they are making a factual statement.

Piracy costs the movie industry approximately thirty billion dollars a year. If it continues, it will affect their ability to make new movies.

This is a descriptive statement. It is speculative -- predicting a cause and effect -- but does not take a moral stance.

It's wrong to take things that don't belong to you, even if they are not physical objects.

This is a normative statement. The speaker is explicitly saying that people should not download movies illegally.

terms to know

Normative Argument

An argument that argues towards what one ought to do, not what is already true.

Normative

A statement or argument about what one ought to do, not what is already true.

Descriptive

A statement or argument about what is actually true, in contrast to normative statements.