section_path: Folk beliefs
section_name: Folk beliefs
paragraph_text: Folk beliefs
  
  The truth predicate " P is true" has great practical value in human language, allowing efficient endorsement or impeaching of claims made by others, to emphasize the truth or falsity of a statement, or to enable various indirect (Gricean) conversational implications. Individuals or societies will sometime punish "false" statements to deter falsehoods; the oldest surviving law text, the Code of Ur-Nammu, lists penalties for false accusations of sorcery or adultery, as well as for committing perjury in court. Even four-year-old children can pass simple " false belief " tests and successfully assess that another individual's belief diverges from reality in a specific way; by adulthood there are strong implicit intuitions about "truth" that form a "folk theory" of truth. These intuitions include:
  
  Like many folk theories, the folk theory of truth is useful in everyday life but, upon deep analysis, turns out to be technically self-contradictory; in particular, any formal system that fully obeys "capture and release" semantics for truth (also known as the T-schema), and that also respects classical logic, is provably inconsistent and succumbs to the liar paradox or to a similar contradiction.