Chapter 13 Summary

In order to support your claims, whether informative or persuasive, it is important to understand how to construct an argument as well as how to recognize the strength or weakness of reasoning and evidence. In order to develop your argument, you need to draw together reasoning and evidence. You can use a formal logical argument called a syllogism, including a major premise, minor premise, and a conclusion. You can also use more informal logic like the Toulmin structure, and build out an argument that includes a claim, grounds, warrant, backing, rebuttal, and qualifier.

In order to avoid errors in reasoning that may deceive audiences, called fallacies, you must consider credibility, relevance, and sufficiency. Credibility relates to the believability of evidence, which is determined by consistency and accuracy. Be careful not to use manufactured or questionable statistics, or use biased sources, or quote an expert outside of their field of expertise. Relevance means that evidence needs to relate directly to the claim. Various non sequitur fallacies, like ad hominem or ad populum happen when claims do not follow from the evidence. Sufficiency refers to the burden of proof required to prove a claim. Using a self-selected sample instead of a random sample, using an inadequate sample, using a hasty generalization through inductive reasoning, mistaking correlation for causation, and false analogies all are fallacies that exhibit insufficiency.