Introduction to Logical Fallacies

A logical fallacy is an error in reasoning that undermines the logic of an argument.

Sometimes fallacies are used as intentional deception, and other times they’re made unconsciously and without malicious intent.

Logical fallacies often feel compelling — not because they’re logically sound, but because they take advantage of cognitive biases we’ve discussed in the previous section.

Logical fallacies are one of the most significant factors in undermining critical thinking. They make unreasonable and irrational arguments sound reasonable and rational, which makes those arguments much easier to absorb and believe. Essentially:

Unfortunately, logical fallacies also show up everywhere. You can find them in politics, advertising, social media, personal conversations, and even academic settings.

Understanding logical fallacies helps you:

• Become more resilient to the manipulation and misinformation you’re likely to encounter throughout your life
• Become better at constructing your own arguments

Each of the following chapters will focus on a specific logical fallacy. There are dozens¹ of logical fallacies, but we’ll just be highlighting the most common ones you’re likely to encounter.

As you read through the chapters, try to:

• Make sure you understand how the fallacy works on a structural level (if you have any confusion, ask your instructor for clarification!).
• See if you can spot examples of them in your daily life.
• Notice that sometimes different logical fallacies can overlap or be used in combination with others.