metalanguage

Alfred Tarski describes metalanguage as the richer superset of object language, where statements about the truth or falsehood of object language statements can be made.

• "Achilles is fast" is a true statement.
• "Angels are male" cannot be tested or evaluated for truth.
• "Snow is red" is a false statement.

Statements about the truth of metalanguage statements must be constructed in progressively higher levels of metalanguage.

Lewis Carroll's "What the Tortoise Said to Achilles"