Understanding Fallacies: Formal and Informal Reasoning Errors
Understanding Fallacies
A fallacy is an invalid or incorrect reasoning that appears to be correct. The reasoning is misleading or incorrect (false) but pretends to be convincing or persuasive.
Informal Fallacies
Informal fallacies are arguments where the premises are unsuitable to justify the desired conclusion. They attempt to convince without providing good reasons, resorting to irrelevant or irrational factors. Even when the premises contain sound information, they lead to a conclusion different from the intended one.
Types of Informal Fallacies
- Ad Hominem Fallacy (Directed Against the Person): Reasoning that attacks or discredits the person defending a position instead of presenting adequate reasons to refute that position. Example: “Environmentalists say that we consume too much energy, but pay no attention because environmentalists always exaggerate.”
- Ad Baculum Fallacy (Appeal to Force): Reasoning that uses the threat of force or fear to reach a conclusion. It’s an argument that may win but isn’t convincing. Example: “Do not come to work at the store with that piercing; remember who holds the purse strings.”
- Ad Verecundiam Fallacy (Appeal to Authority): Reasoning that supports a conclusion or opinion without justified reasons, merely by appealing to an authority, the majority, or custom. While appealing to a recognized authority can be legitimate in some cases, it’s not always a guarantee. Example: “The mayor said the best thing for the health of citizens is to pave all the squares.”
- Ad Populum Fallacy (Appeal to Emotion): Reasoning that omits relevant reasons and outlines reasons unrelated to the conclusion but known to be accepted by the audience, arousing feelings and emotions. It’s a demagogic or persuasive argument. Example: “We have to prohibit people from outside from coming. What will happen to our children if foreigners rob them of work and bread?”
- Ad Ignorantiam Fallacy (Appeal to Ignorance): Reasoning that defends the truth (or falsity) of a statement by claiming that it cannot be proven otherwise. Example: “Nobody can prove that there is no influence of the stars in our life; therefore, the predictions of astrology are true.”
- Tu Quoque Fallacy: Literally meaning “you too.” This fallacy is a special case of the ad hominem fallacy. It deflects the question by recalling the opponent’s past statements or actions to point out inconsistencies rather than addressing the current argument.
Formal Fallacies
Formal fallacies are invalid arguments that are often accepted due to their resemblance to valid forms of reasoning or inference. The error often goes unnoticed.
Types of Formal Fallacies
- Fallacy of Affirming the Consequent: Reasoning based on a conditional statement (if p, then q) and concluding p after stating q. It resembles the valid argument form modus ponens.
- Fallacy of Denying the Antecedent: Reasoning based on a conditional statement (if p, then q) and concluding the denial of q after denying p. It resembles the valid argument form modus tollens.
- Fallacious Disjunctive Syllogism: Reasoning that starts from a disjunction and asserts one of the components, concluding the denial of the other. It maintains similarity to the valid argument form known as disjunctive syllogism.