# Definition:Universal Statement

## Definition

A universal statement is one which expresses the fact that all objects (in a particular universe of discourse) have a particular property.

That is, a statement of the form:

$\forall x: P \paren x$

where:

$\forall$ is the universal quantifier
$P$ is a predicate symbol.

It means:

All $x$ (in some given universe of discourse) have the property $P$.

Note that if there exist no $x$ in this particular universe, $\forall x: P \paren x$ is always true: see vacuous truth.

### Bound Variable

In the universal statement:

$\forall x: P \paren x$

the symbol $x$ is a bound variable.

Thus, the meaning of $\forall x: P \paren x$ does not change if $x$ is replaced by another symbol.

That is, $\forall x: P \paren x$ means the same thing as $\forall y: P \paren y$ or $\forall \alpha: P \paren \alpha$. And so on.

## Also known as

A universal statement can also be referred to as a universal sentence, or more wordily, a sentence of a universal character.