affirmative proposition

logic

Also known as: affirmation

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July 23, 2026

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In logic, an affirmative proposition is a statement that asserts something is true. It is one of the basic forms of a categorical proposition, which states that the predicate is affirmed of the subject. For example, "Every S is P" is an affirmative proposition. This contrasts with negative propositions, which deny something. Affirmative propositions, along with negative ones, form the basis of logical reasoning and can be analyzed using tools like truth tables to determine their truth-value.

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history of logic
Categorical forms
…equivalently “No β is an α.” Particular affirmative: “Some β is an α.” Particular negative: “Some β is not an α.” Indefinite affirmative: “β is an α.” Indefinite negative: “β is not an α.” Singular affirmative: “x is an α,” where “x” refers to only
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…equivalently “No β is an α.” Particular affirmative: “Some β is an α.” Particular negative: “Some β is not an α.” Indefinite affirmative: “β is an α.” Indefinite negative: “β is not an α.” Singular affirmative: “x is an α,” where “x” refers to only
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