The Modal Scope Fallacy is a type of logical error that occurs when someone misinterprets the scope of a modal operator (e.g., “it is possible,” “it is necessary”) in a sentence or argument. This fallacy involves ignoring or misunderstanding the way modal operators interact with other elements in a sentence. Example: “It is possible for […]

In this example, the premise states an actual fact about the weather, but the conclusion drawn is a modal statement about possibility. This is a fallacy because the mere fact that something is happening does not imply that it was always possible or necessary. Formal Representation: R (Premise: It is raining outside)∴ ◇R (Fallacious Conclusion: […]

The Fallacy of the Undistributed Middle is a type of logical error that occurs when someone mistakenly assumes that two groups or categories are related simply because they share a common characteristic. This fallacy involves ignoring the fact that the shared characteristic may not be distributed equally among all members of each group. Example: “All […]

The Negative Conclusion from Affirmative Premises is a type of logical error that occurs when someone mistakenly draws a negative conclusion (e.g., “not all x are y”) from premises that only provide positive information (e.g., “all x are y” or “some x are y”). Example: “All employees who work on weekends receive overtime pay.” (Premise […]

The Illicit Minor is a type of logical error that occurs when someone mistakenly uses a specific case or instance as the minor premise in an argument, but then draws a conclusion that applies to all cases. Example: “All mammals are warm-blooded.” (Major premise)“The lion is a mammal and lives in the savannah.” (Minor premise)“Therefore, […]

The Illicit Major is a type of logical error that occurs when someone mistakenly uses a universal statement (all) as the major premise in an argument, but then draws a conclusion that only applies to some or one specific case. Example: “All humans are mortal.” (Major premise)“Socrates was human.” (Minor premise)“Therefore, Socrates is the only […]

The Fallacy of Exclusive Premises is a type of logical error that occurs when someone mistakenly concludes a statement from two or more premises that are mutually exclusive. Example: “Either John is a doctor or he is an engineer.” (Exclusive premise 1)“John is not a doctor.” (Exclusive premise 2)“Therefore, John must be an engineer who […]

The Affirmative Conclusion from a Negative Premise (also known as Illicit Negative) is a type of logical error that occurs when someone mistakenly concludes an affirmative statement from one or more negative premises. Example: “Nobody knows the answer to this question.” (Negative premise)“Therefore, John knows the answer.” (Affirmative conclusion) In this example, the argument starts […]

The Existential Fallacy is a type of logical error that occurs when someone mistakenly assumes that because something exists or has existed, it must have always existed or will continue to exist. Example: “Because some people have always been poor, poverty must be an inherent and eternal aspect of human society.” (Existential Fallacy) In this […]

The Denying the Antecedent is a type of logical error that occurs when someone mistakenly assumes that because the antecedent (the “if” part) of a conditional statement is false, the consequent (the “then” part) must also be false. Example: “If it rains, the streets will be wet.” (Conditional statement)“It didn’t rain.”“Therefore, the streets are not […]