Deploying a Rational Appeal

1. Forming a Rational Appeal

A rational appeal uses logical arguments and factual evidence to persuade individuals that whatever thesis you are supporting is viable and likely to result in the obtainment of goals. When you focus on rational appeals you are dealing with the mind and cognition of the audience.

The study of rhetoric has historically focused on three types of persuasive appeals: ethos, pathos, and logos. Our focus on reasoning and how you to use evidence to reason with your audience is part of the study of logos.

Additionally, you are concerned with invention, which is the first of the five canons of rhetoric identified by Cicero, the classical Roman rhetorician. Invention is how you formulate arguments based on logos— rational appeal or logic.

When you appeal to reason, you use logically constructed arguments using your evidence to persuade your audience to agree with you. You might use many different forms of evidence to support your rational appeal.

Basically, the burden of proof is on you the speaker as you develop your appeals to the audience. As you deploy a rational appeal consider: Is my reasoning sound, and what will the audience accept as a believable evidence?

term to know

Invention

The formulation of arguments based on logos--rational appeal or logic.

1a. Is Your Reasoning Sound?

Prior to your speech, it is important to consider the soundness of your evidence and reasoning.

Deductive reasoning: For example, if you are engaging in deductive reasoning, you will want to consider whether or not the audience is likely to accept the general premise as valid and true before you attempt to deduce other ideas or courses of action based on the general premise.

If you are quoting an authority and drawing conclusions from the authority, it is important to ask if the audience will accept or believe the authority. Remember to quote or use sources that the audience is familiar and will believe; using other authorities or sources will likely not be productive.

Inductive reasoning: If you are engaging in inductive reasoning, you will want to consider whether you have observed or collected enough evidence to draw a highly probable conclusion. Or, did you draw a hasty conclusion based on too few examples or observations?

If you are using statistical evidence as part of your inductive reasoning, it is important to consider how the data was collected and whether it is truly valid. If you do not have valid statistical data, then the inductions will not be valid.

Before using any data, ask:

• Is the source biased, or perceived as biased?
• Is the source competent in the field being consulted?
• Is the information current?

Associative reasoning (analogy): When engaging in associative reasoning, you will want to make sure that the ideas are indeed similar and that there are no obvious or outstanding differences which would negate the association in the mind of your audience.

2. Address Resistance and Concerns of the Audience

Finally, in persuasive situations it is important to anticipate the potential resistance and counterarguments your audience might feel.

When you have a sense of what objections the audience might raise, you can and should address the most significant points of disagreement in your message.

Arguments from reason (logical arguments) have some advantages, namely that data are (ostensibly) difficult to manipulate, so it is harder to argue against such an argument; and such arguments make the speaker look prepared and knowledgeable to the audience, enhancing ethos.

In addition, if you have built ethos with the audience then it will enhance your appeal with arguments from reason.