A fallacy is a defect in an argument that consists in either a mistake in reasoning or the creation of an illusion that makes a bad argument appear good. A fallacy, therefore, represents a mistake in reasoning, or a bad inference from one or more premises to a conclusion. Besides committing a fallacy (a mistake in reasoning), the other way an argument can be defective is to have one or more false premises. If an argument either (1) has one or more false premises or (2) commits a fallacy, then the argument is either unsound (for deductive arguments) or uncogent (for inductive arguments). Conversely, if an argument is either unsound or uncogent, then it either has false premises or it commits a fallacy, or both. There are two types of fallacies: formal and informal. A formal fallacy occurs when a deductive argument form employs an invalid arrangement of terms or statements. Thus, formal fallacies can be detected by inspecting the form of the argument alone, and they occur only in deductive arguments. By contrast, an informal fallacy can be detected only by inspecting the content of an argument.