Avoiding Logical Fallacies

In addition to considering the most effective tools and strategies for persuading their audiences, communicators must be mindful about avoiding logical fallacies. The term logical fallacy refers to a structural flaw in an argument that inherently weakens it. A logical fallacy therefore occurs not necessarily when information itself is false or wrong, but when a communicator puts material together in a way that makes their conclusions invalid.

Logical fallacies do not always reflect the integrity of a position. It is very possible to make a bad argument for a good cause. For example, a nutritionist can make a very reasonable case for becoming a vegan by drawing from scientific research on the health benefits of a plant-based diet, the social and environmental impacts of factory farming, and their experiences as a professional. However, if the nutritionist were to argue, “Going vegan is the right thing to do because Benjamin Franklin would have wanted it,” or “Anyone who eats meat is a sociopath,” then they would undermine their position by the faultiness of their reasoning.

To audiences, the presence of logical fallacies in a speaker’s or writer’s argument can be indicative of a lack of thorough thinking or even arguing in bad faith. Thus, being aware of the different types of logical fallacies and testing your argument against them is essential to effective persuasion. Table 4.1 below lists common logical fallacies, their definitions, and examples of how they might be used in a speech or written document.

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