Logical fallacies are examples of fallacious, or faulty, arguments. At best, they represent flawed reasoning—making claims that are not supported by reasons or warrants, or drawing conclusions that don’t match up to the information you have. At worst, they can be deliberate attempts to mislead or confuse someone, to persuade through providing misinformation, usually to serve some hidden agenda. Many of the logical fallacies we will examine are common mistakes we all make, but some of them are established propaganda techniques.

The ability to recognize and critically analyze logical fallacies is important for both writers and readers.

As readers—receivers and consumers of information—we need to be able to recognize logical fallacies so we can evaluate the credibility of our sources of information; it is an important part of information literacy.

As writers—producers of information—we must be able to recognize logical fallacies in order to eliminate them from our own process of reasoning. Effective and responsible persuasive writing makes valid logical arguments, and avoids all logical fallacies.

Faulty reasoning can take many forms, but there are some patterns of flawed logic that have become so common that we can name and classify them.

The posts that follow will list and examine some common logical fallacies. I have divided these fallacies into three categories:

• Bad Form – mistakes in how one draws conclusions from the available evidence
• Use and Abuse of Evidence – how evidence itself can confuse and mislead
• Misdirection – propaganda techniques for sidestepping the burden of proof

As you learn names for the different ways reasoning can go wrong, keep in mind that some of these errors may overlap, and that different fallacies can often appear in combination.