Definition:Universal Affirmative

Definition

A universal affirmative is a categorical statement of the form:

Every $S$ is $P$

where $S$ and $P$ are predicates.

In the language of predicate logic, this can be expressed as:

$\forall x: \map S x \implies \map P x$

Its meaning can be amplified in natural language as:

Given any arbitrary object, if it has the property of being $S$, then it also has the quality of being $P$.

The universal affirmative $\forall x: \map S x \implies \map P x$ can be expressed in set language as:

$\set {x: \map S x} \subseteq \set {x: \map P x}$

or, more compactly:

$S \subseteq P$

Traditional logic abbreviated the universal affirmative as $\mathbf A$.

Thus, when examining the categorical syllogism, the universal affirmative $\forall x: \map S x \implies \map P x$ is often abbreviated:

$\map {\mathbf A} {S, P}$

The abbreviation $\mathbf A$ for a universal affirmative originates from the first vowel in the Latin word Affirmo, meaning I affirm.