Short answers, pulled from the story.
Truth is conformity to reality or fact, and it contrasts with falsity or misrepresentation that fails to align with the world. It is typically treated as a property of truthbearers such as sentences, propositions, or beliefs that describe things as they are. Its precise definition remains contested among philosophers.
The main theories of truth include the correspondence theory, the coherence theory, the pragmatic theory, the semantic theory, and deflationary theories. Correspondence holds that a statement is true if it corresponds to facts, while coherence ties truth to logical consistency among beliefs. Pragmatists define truth by practical consequences, and deflationists deny that truth has any significant intrinsic nature.
The liar paradox involves a statement with an inconsistent truth assignment, such as "I am lying" or "This statement is false." If the statement is true, it follows that it is false, and if it is false, it follows that it is true. Such paradoxes challenge theories of truth and arise when a language contains its own truth predicate.
The semantic theory of truth was originally formulated by Alfred Tarski, who limited it to the analysis of formal languages. It characterizes truth through T-sentences that connect an object language to a meta-language. Donald Davidson later extended Tarski's approach to natural languages.
Many religious traditions regard truth as a virtue and ground it in a divine source. The Abrahamic traditions link truth to the divine, seen in the Jewish El Emet, Jesus's statement "I am the way, the truth, and the life," and the Islamic Al-Haqq. In Hinduism truth is satya, and Buddhism teaches the Four Noble Truths and a theory of two truths.
A posteriori truths require sensory experience, such as observing that water boils at 100 degrees Celsius at standard atmospheric pressure. A priori truths can be known through pure reasoning, such as a proof of a mathematical theorem. The distinction rests on the source of knowledge.