What is defined as an error in reasoning?

The term that is defined as an error in reasoning is a fallacy. A fallacy represents a flaw in logical reasoning that can lead to invalid conclusions. It may arise from incorrect premises, misleading arguments, or emotional appeals that distract from valid reasoning. Understanding fallacies is crucial in both critical thinking and argumentation, as they help identify weaknesses in an argument.

In contrast, an assumption refers to something that is accepted as true without proof, which is not inherently an error in reasoning but rather a starting point for further argumentation or inquiry. A hypothesis is a proposed explanation made on the basis of limited evidence as a starting point for further investigation, and it represents a testable statement rather than an error. A contradiction occurs when two statements are in direct opposition to each other, which may highlight a problem in reasoning but does not encompass the broader range of logical errors identified as fallacies.