Definition:Particular Affirmative

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A particular affirmative is a categorical statement of the form:

Some $S$ is $P$

where $S$ and $P$ are predicates.

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

$\exists x: \map S x \land \map P x$

Its meaning can be amplified in natural language as:

There exists at least one object with the property of being $S$ which also has the quality of being $P$.

Set Theoretic interpretation of Particular Affirmative

The particular affirmative $\exists x: S \left({x}\right) \land P \left({x}\right)$ can be expressed in set language as:

$\left\{{x: S \left({x}\right)}\right\} \cap \left\{{x: P \left({x}\right)}\right\} \ne \varnothing$

or, more compactly:

$S \cap P \ne \varnothing$

Also denoted as

Traditional logic abbreviated the particular affirmative as $\mathbf I$.

Thus, when examining the categorical syllogism, the particular affirmative $\exists x: \map S x \land \map P x$ is often abbreviated:

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

Linguistic Note

The abbreviation $\mathbf I$ for a particular affirmative originates from the second vowel in the Latin word affIrmo, meaning I affirm.

Also see