1. a mistaken belief or false idea
2. faulty reasoning or a logical error in an argument
Usage: logic; formal

Examples

• It’s a fallacy to think that expensive products are always better quality.
• The politician’s argument contained several logical fallacies.
• The fallacy that hard work always leads to success ignores many factors.
• Her reasoning was based on the fallacy that correlation implies causation.
• The ad hominem attack is a common fallacy in debates.
• Don’t fall for the fallacy that newer technology is automatically superior.