Fallacy

A fallacy occurs when faulty or invalid reasoning is used to build an argument that can seem logical if the flaw goes unnoticed. The concept entered Western thought through Aristotle’s *De Sophisticis Elenchis*. Fallacies are often split into two main categories: formal and informal. They can be employed deliberately to deceive and manipulate, or they can arise unintentionally from human shortcomings like carelessness, cognitive or social biases, ignorance of proper reasoning standards, or even a lack of understanding about the context—for instance, legal arguments depend heavily on context for their soundness. A fallacy does not guarantee a false conclusion; it simply results from invalid reasoning. An example is the fallacy of affirming the consequent. Formal fallacies involve a flaw in the structure of a deductive argument, making it invalid. Informal fallacies, on the other hand, stem from errors in reasoning that are not about logical form; arguments with informal fallacies can be formally valid yet still fallacious. A special case is the mathematical fallacy, an intentionally invalid proof with a hidden error, often created for educational purposes to show false proofs of obvious contradictions. Fallacies are types of erroneous reasoning that make arguments logically unsound. As noted in *The New Handbook of Cognitive Therapy Techniques*, they include “unsubstantiated assertions that are often delivered with a conviction that makes them sound as though they are proven facts.” Informal fallacies are common in mass media like television and newspapers. Recognizing fallacies can help people spot them in their own or others’ writing, and avoiding them can improve one’s ability to produce sound arguments. Evaluating whether an argument is fallacious can be tricky because arguments exist on a spectrum of soundness; an argument with multiple parts may have both sound and fallacious sections. Whether a specific argument is fallacious often depends on its content rather than its form—for example, a probabilistically valid instance of the formally invalid form of denying the antecedent or affirming the consequent can occur. Fallacious arguments usually look like good ones because most fallacious instances of an argument form have a similar, non-fallacious counterpart. Thus, judging an argument as fallacious often requires evaluating its context. Recognizing fallacies in everyday arguments is difficult because they are often wrapped in rhetorical patterns that hide logical connections. Informal fallacies can exploit emotional, intellectual, or psychological weaknesses in an audience. Developing the skill to identify fallacies helps strengthen reasoning by exposing weak links between premises and conclusions, allowing a better distinction between what seems true and what is true. Argumentation theory offers another way to understand and classify fallacies. In pragma-dialectics, an argument is seen as an interactive protocol between people trying to resolve a disagreement based on the merits of the case. This protocol has normative rules, and violating those rules is considered fallacious because it hinders the resolution of the disagreement. Fallacies are used in place of valid reasoning to persuade, appearing in mass media such as propaganda, advertisements, politics, newspaper editorials, and opinion-based news shows. Fallacies are generally classified by structure or content—as formal or informal. Informal fallacies can be subdivided into categories like linguistic, relevance through omission, relevance through intrusion, and relevance through presumption. Alternatively, they may be classified by the process that produces them: material fallacies (content), verbal fallacies (linguistic), and formal fallacies (error in inference). Material fallacies fit under the broader category of informal fallacies, while verbal fallacies can belong to either formal or informal classifications. For example, equivocation is a word- or phrase-based ambiguity, whereas the fallacy of composition involves premise- and inference-based ambiguity. The Greek philosopher Aristotle (384–322 BC) first systematized logical errors into a list to help refute an opponent’s thesis and win arguments. His *Sophistical Refutations* (*De Sophisticis Elenchis*) identifies thirteen fallacies, divided into two major types: linguistic fallacies (verbal) and non-linguistic fallacies (material). Verbal fallacies depend on language and involve improper or ambiguous word use; material fallacies are errors in what the arguer is talking about. An example of a language-dependent fallacy is a debate over whether the wise or the ignorant are learners.