As with claims and evidence, you can also use different types of warrants to try to persuade audience members to accept the validity of your claims:

Motivational Warrants: Appeals to Audience Needs and Values

No doubt you have seen television and magazine advertisements asking viewers to give just pennies a day to sponsor a starving child in a distant land. The claim may say, “You can easily afford to join this organization dedicated to ending the hunger of thousands of children.” The evidence may be stated as “For the price of one soft drink you can feed a child for a week.” The warrant is something like, “You don’t want any child to starve or go without proper medical care.” Motivational warrants use the needs, desires, emotions, and values of audience members as the basis for accepting some evidence as support for a claim, and thus accepting the claim itself. More often than not, motivational warrants are implied rather than stated outright. In terms of the ad to support a starving child, we don’t have to be told that we don’t want children to starve; if the value or desire is meaningful to us, we realize it instinctively.

The following is a motivational warrant for a claim of policy advocating a higher minimum wage:

Although appealing to the needs, desires, and values of audience members requires audience analysis (see Chapter 6), some values—such as fairness, human dignity, financial security, health, and happiness—are universally shared and generally can serve safely across various audiences as the basis for motivational warrants.

Authoritative Warrants: Appeals to Source Credibility

Just as one form of evidence relies on the speaker’s own expertise, authoritative warrants rely on an audience’s beliefs about the credibility or acceptability of a source of evidence. For example, in terms of sponsoring a hungry child, the speaker might make the claim that “We should contribute financially to an agency that feeds hungry children.” The speaker’s evidence is that any amount we give, however small, will go far in meeting the agency’s objectives. As a warrant, the speaker notes that a former U.S. senator works with the agency and its recipients; perhaps she is even the person delivering the message.

The success or failure of authoritative warrants rests on how highly the audience regards the authority figure. If listeners hold the person in high esteem, they are more likely to find the evidence and the claim acceptable. Thus authoritative warrants make the credibility of sources of evidence all the more important.

In support of the claim that “In war zones, rape should be prosecuted as a war crime,” you could offer an authoritative warrant as follows: “According to Angelina Jolie, Hollywood actress and Special Envoy to the United Nations Refugee Agency, there are hundreds of thousands of survivors of sexual violence, but only a handful of prosecutions because the world has not made the issue a priority”⁷; this gives both the evidence (rapes in war zones) and the warrant (the specific famous person is Angelina Jolie)⁸ in the same sentence.

If you happen to be highly knowledgeable on a subject, an authoritative warrant can be made by reference to yourself. In this case, the warrant provides the speaker’s knowledge and opinions as evidence. Your experience offers evidence for the claim, and you, having had the experience, give warrant to the evidence.

Substantive Warrants: Appeals to Factual Evidence

Rather than audience needs and values (motivational warrant) or source credibility (authoritative warrant), substantive warrants target the audience’s faith in your factual evidence as justification for the argument. For example, if you claim that “Climate change is linked to stronger hurricanes,” and offer as evidence that “We have seen a consistent pattern of stronger hurricanes and warmer oceans,” a substantive warrant might be: “Hurricanes and tropical storms get their energy from warm water.” The warrant is based on factual evidence.

There are several types of substantive warrants, or ways of justifying claims on the basis of evidence. Two that occur commonly in speeches are causation and analogy. Warrants by cause (also called causal reasoning) offer a cause-and-effect relationship as proof of the claim. In causal reasoning, the speaker argues that one event, circumstance, or idea (the cause) is the reason (effect) for another. The example above about climate change offers an instance of causal reasoning, or warrant by cause. The warrant substantiates the relationship of cause (climate change) to effect (stronger hurricanes) on the scientific (i.e., factual) basis of the process of hurricane formation.

Critics of the federal deficit often reason by cause when they suggest too much government spending leads to debt. Their opponents also reason by cause when they claim that the actual cause of the debt is insufficient taxes on the rich. Rather than suggesting a cause-to-effect relationship, however, either the critic or the opponent might suggest an effect-to-cause relationship, as in: “Overspending on social programs [EFFECT] leads to the deficit [CAUSE].” Similarly, a speaker might argue the following:

Older age is assumed to be a cause of Candidate X’s loss in the senatorial campaign. The warrant substantiates the relationship of cause (age) to effect (loss of race) on the basis of society’s negative stereotypes of older people.

As pointed out in the accompanying checklist, when using warrants by cause, it is essential to make relevant and accurate assertions about cause and effect.

Warrants by analogy (also called reasoning by analogy) compare two similar cases and imply that what is true in one case is true in the other. The assumption is that the characteristics of Case A and Case B are similar, if not the same, and that what is true for B must also be true for A.

Reasoning by analogy occurs frequently in persuasive speeches, especially those addressing claims of policy. Consider this example:

Arguing a claim using analogical reasoning requires acknowledging not just the similarities but also the limits of the analogy, citing differences as well as parallels (see also the discussion of analogies in Chapter 23). The strength of the argument will rest on whether the similarities the speaker offers are convincing to the audience.