Before we turn to specific types of evidence, let’s consider logical fallacies: potential vulnerabilities or weaknesses in an argument. Practically speaking, the logical breakdown in most weak arguments occurs in the use of evidence, since evidence is what we use to prove arguments. So a more practical definition of a fallacy might be a failure to make a logical connection between the claim and the evidence used to support that claim. Fallacies may be accidental, but they can also be used deliberately to manipulate or deceive.

Regardless of whether they are intentional or unintentional, logical fallacies work against the clear, civil discourse that should be at the heart of argument. By checking for logical fallacies in a published argument that you’re analyzing, you can identify weak points; by checking for fallacies in your own writing, you can revise to strengthen your argument. It’s more important that you notice these fallacies and be able to describe what you see than it is to be able to label them by their technical names. The concepts are more important than the terms.