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“In our daily lives, we’re constantly hearing or making persuasive arguments. We may be listening to a colleague’s argument for why we should support one of her initiatives. We may hear an argument for why we should buy a certain product. Or we may need to make our own argument to get approval for one of our projects.

How should we evaluate arguments that people make to persuade us? And how should we construct our own arguments to be the most effective?

T. Edward Damer shares an excellent framework for creating good arguments in his book Attacking Faulty Reasoning. Damer begins by explaining what an argument is. At its core, an argument consists of a conclusion and one or more premises, or claims. The conclusion is what the communicator wants his or her audience to accept, and the premises are the reasons for believing the conclusion to be true. According to Damer, here’s the formal definition of an argument:

“An argument is constituted by two or more explicit and/or implicit claims, one or more of which supports or provides evidence for the truth or merit of another claim, the conclusion.”

So how do you craft a good argument? Damer shares the five principles for developing a good argument:

Structure

Relevance

Acceptability

Sufficiency

Rebuttal

Let’s look at each of these principles in more detail.

1. Structure

A good argument must meet the fundamental structural requirements of a well-formed argument.

“Such an argument does not use reasons that contradict each other, that contradict the conclusion, or that explicitly or implicitly assume the truth of the conclusion.”

To evaluate any argument for whether it violates the principle of Structure, ask the following questions:

Does the communication include at least one reason to support the conclusion as being true? If it doesn’t, then it’s not an argument — it’s merely an opinion. An unsupported conclusion is an opinion; a conclusion supported by reasons is an argument.

Could any of the key premises be interpreted as making the same claim as the conclusion? If so, then it’s a “circular argument” — there’s no independent reason given to support the conclusion. Since A, therefore A. No one is likely to use the exact same words in both the premise and the conclusion, so you need to ask yourself if a premise can be interpreted as making the same claim as the conclusion. “Joe is nuts,” Gary says. “Why do you say that?” I ask. “Because he’s so crazy,” Gary replies. Since A, therefore A.

Do any of the premises contradict another premise, or does the conclusion contradict any of the premises?

2. Relevance

The reasons that a communicator provides as part of his or her argument must be relevant for the truth or merit of the conclusion. What makes a premise relevant?

“A premise is relevant if its acceptance provides some reason to believe, counts in favor of, or has some bearing on the truth or merit of the conclusion. A premise is irrelevant if its acceptance has no bearing on, provides no evidence for, or has no connection to the truth or merit of the conclusion.”

To assess whether an argument violates the principle of Relevance, ask these two questions:

If the premise were true, does it make you more likely to believe that the conclusion is true? If yes, the premise is probably relevant. If no, then the premise is probably not relevant.

Even if the premise were true, should it be a consideration for accepting the truth of the conclusion? If no, then the premise is probably not relevant. “Jerry is over 6 ft. tall. So he must be good at basketball.” “Avatar is an artistic masterpiece. After all, it was the highest grossing film of the year.”

3. Acceptability

The reasons that a communicator provides in his or her argument should be likely to be accepted by a mature, rational adult. As Damer writes, a premise should be acceptable to a mature, rational adult if it meets the following standards of premise acceptability:

“A claim that is a matter of undisputed common knowledge.”

“A claim that is confirmed by one’s own personal experience or observation.”

An “uncontroverted eyewitness testimony,” or an “uncontroverted claim from a relevant authority.”

“A relatively minor claim that seems to be a reasonable assumption in the context of the argument.”

By contrast, a premise should be rejected by a mature, rational adult if it meets the following conditions of premise unacceptability:

“A claim that contradicts credible evidence, a well-established claim, or a legitimate authority.”

“A claim that is inconsistent with one’s own experiences or observations.”

“A claim that is based on another unstated but highly questionable assumption.”

An argument meets the acceptability principle when each of its premises conforms to at least one of the standards of acceptability and none of its premises conforms to the conditions of unacceptability.

To assess whether an argument violates the principle of Acceptability, ask the following questions:

Is the premise provided one that a mature, rational adult would likely accept?

What evidence is provided as part of the claim, and does it conform to the standards of acceptability or the conditions of unacceptability?

Is the premise based on an unstated assumption that a mature, rational adult not be willing to accept?

4. Sufficiency

A communicator making an argument should provide reasons that are sufficient to justify the acceptance of his or her conclusion.

“There must be a sufficient number of relevant and acceptable premises of the appropriate kind and weight in order for an argument to be good enough for us to accept its conclusion.”

This principle is one of the most difficult to apply, because it’s a judgment call. There are no black-and-white guidelines for what constitutes a “sufficient” number and weight of reasons to accept a conclusion. Often, it’s a disagreement about the weight or sufficiency of the premises in an argument that prevents two intelligent and well-meaning people from reaching the same conclusion based on the same available evidence.

To evaluate whether an argument violates the principle of Sufficiency, ask the following questions:

Are the reasons provided enough to drive to the arguer’s conclusion? If not, the argument violates the sufficiency principle.

Is the premise based on insufficient evidence or faulty causal analysis? Some premises provide evidence that is based on too small a sample or unrepresentative data. Or the evidence is based on the personal experience of the arguer, or of a small set of acquaintances that the arguer knows. The premise may be based on faulty causal analysis — assuming A caused B, even though the two events were unrelated.

Is some key or crucial evidence missing that must be provided in order to accept the argument?

5. Rebuttal

A good argument includes an effective rebuttal to all anticipated serious criticisms of the argument.

“An argument cannot be a good one if it does not anticipate and effectively rebut or blunt the force of the most serious criticisms against it and the position that it supports… A good arguer should be constantly mindful of the fact that an argument is not finished until one has ‘finished off’ the criticisms and counterarguments.”

There are multiple ways that an argument can violate the Rebuttal principle. Arguers often use diversionary tactics instead of making effective rebuttals.

“For example, arguments that misrepresent the criticism, bring up trivial objections as a side issue, or resort to humor or ridicule are using devices that clearly fail to make effective responses. The same can be said of those arguments that ignore or deny the counterevidence against the position defended. Finally, some arguers try to avoid responding to a criticism by attacking the critic instead of the criticism.”

To assess whether an argument fails to meet the Rebuttal principle, ask the following questions:

Does the argument provided address the strongest counterarguments effectively?

Does the arguer anticipate and address serious weaknesses in the argument?

Does the argument show why alternative positions are flawed?

Making your own argument stronger

We can use the five principles above to evaluate arguments that others present to us. But how do we strengthen our own arguments when we craft them? Using each principle, Damer provides some suggestions for how to improve our arguments.

Structure: Explicitly call out your conclusion and the supporting reasons, so that they are easy to recognize and follow. Ensure that your premises (1) do not contradict each other or the conclusion, and (2) do not assume the truth of the conclusion. Make explicit any key assumptions that you’re using.

Relevance: Ensure that all materials you’re presenting as part of your argument are relevant. Cut out anything that’s not relevant. Don’t weaken your argument by including irrelevant premises.

Acceptability: Whenever possible, substitute less controversial claims for more controversial ones. Soften, if possible, any absolute claims to make them more acceptable. (e.g. “most politicians” instead of “all politicians”) Don’t use highly questionable evidence or assumptions.

Sufficiency: Continue adding relevant premises if they contribute to the number and weight of the reasons that drive to your conclusion. Put yourself in your audience’s place, and ask if the reasons are sufficient to accept your conclusion. If an important premise is controversial, support it with sub-premises and additional evidence.

Rebuttal: Be as exhaustive as necessary in your rebuttal. Some arguments may need to rebut a single criticism, but more controversial or divisive issues may require multiple rebuttals. Declare up front what the weakest parts of your argument are and proactively address them to blunt the force of your opponent’s counterarguments.

In our professional and personal lives, we’re bombarded by persuasive messages — arguments — designed to get us to accept a conclusion. On the flip side, we ourselves may need to make a persuasive argument to get support for our proposals and positions. What makes a good argument? T. Edward Damer shares five key principles for every good argument:

Structure

Relevance

Acceptability

Sufficiency

Rebuttal

Arguments must conform to a well-formed structure: first, they must contain reasons (or else they’re merely opinions); and second, they must contain reasons that don’t contradict each other or assume the truth of the conclusion. The reasons provided in an argument must be relevant to the truth or merit of the conclusion. Furthermore, these reasons should be acceptable to a mature, rational adult. The reasons should be sufficient in number and weight to drive to the argument’s conclusion. And finally, the argument should anticipate and address any serious criticisms proactively, to rebut the criticisms and blunt the force of any counterattacks.

We can use these principles to critically evaluate the arguments of others, and thus arrive at independent, well thought-out conclusions. Just as importantly, we can use these principles to clarify our logic and craft compelling arguments ourselves. If all of us use these five principles, the quality of our communication — and our thinking — will vastly improve.”