Факт как элемент реальности и познания.

Datum or structured component of reality

A fact is a true datum about one or more aspects of a circumstance. Standard reference works are often used to check facts. Scientific facts are verified by repeatable careful observation or measurement by experiments or other means. For example, "This sentence contains words." accurately describes a linguistic fact, and "The sun is a star" accurately describes an astronomical fact. Further, "Abraham Lincoln was the 16th President of the United States" and "Abraham Lincoln was assassinated" both accurately describe historical facts. Generally speaking, facts are independent of belief and of knowledge and opinion. Facts are different from inferences, theories, values, and objects.

The word fact derives from the Latin factum. It was first used in English with the same meaning: "a thing done or performed"a meaning now obsolete. The common usage of "something that has really occurred or is the case" dates from the mid 16th century. In 1870, Charles Sanders Peirce described in his book "The Fixation of Belief" four methods which people use to decide what they should believe: tenacity, method of authority, a priori and scientific method. The term fact also indicates a matter under discussion deemed to be true or correct, such as to emphasize a point or prove a disputed issue; (e. g., "  the fact of the matter is "). Alternatively, fact may also indicate an allegation or stipulation of something that may or may not be a true fact, (e. g., "the author's facts are not trustworthy"). This alternate usage, although contested by some, has a long history in standard English according to the American Heritage Dictionary of the English Language. The Oxford English Dictionary dates this use to 1729. Fact may also indicate findings derived through a process of evaluation, including review of testimony, direct observation, or otherwise; as distinguishable from matters of inference or speculation. This use is reflected in the terms "fact find" and "fact finder" (e. g., "set up a fact finding commission"). Facts may be checked by reason, experiment, personal experience, or may be argued from authority. Roger Bacon wrote "If in other sciences we should arrive at certainty without doubt and truth without error, it behooves us to place the foundations of knowledge in mathematics."

In philosophy, the concept fact is considered in the branch of philosophy concerned with knowledge, called epistemology and ontology, which studies concepts such as existence, being, becoming, and reality. Questions of objectivity and truth are closely associated with questions of fact. A fact can be defined as something that is the case, in other words, a state of affairs. Facts may be understood as information, which makes a true sentence true: "A fact is, traditionally, the worldly correlate of a true proposition, a state of affairs whose obtaining makes that proposition true." Facts may also be understood as those things to which a true sentence refers. The statement "Jupiter is the largest planet in the solar system" is about the fact that Jupiter is the largest planet in the solar system.

Pascal Engel's version of the correspondence theory of truth explains that what makes a sentence true is that it corresponds to a fact. This theory presupposes the existence of an objective world. The Slingshot argument claims to show that all true statements stand for the same thing, the truth value true. If this argument holds, and facts are taken to be what true statements stand for, then one arrives at the counter intuitive conclusion that there is only one fact: the truth.

Any non trivial true statement about reality is necessarily an abstraction composed of a complex of objects and properties or relations. "Facts possess internal structure, being complexes of objects and properties or relations"

Moral philosophers since David Hume have debated whether values are objective, and thus factual. In A Treatise of Human Nature Hume pointed out there is no obvious way for a series of statements about what ought to be the case to be derived from a series of statements of what is the case. This is called the is–ought distinction. Those who insist there is a logical gulf between facts and values, such that it is fallacious to attempt to derive values (e. g., "it is good to give food to hungry people") from facts (e. g., "people will die if they can't eat"), include G. E. Moore, who called attempting to do so the naturalistic fallacy.

Factuality—what has occurred—can also be contrasted with counterfactuality: what might have occurred, but did not. A counterfactual conditional or subjunctive conditional is a conditional (or "if–then") statement indicating what would be the case if events had been other than they were. For example, "If Alexander had lived, his empire would have been greater than Rome." This contrasts with an indicative conditional, which indicates what is (in fact) the case if its antecedent is (in fact) true—for example, "If you drink this, it will make you well." Such sentences are important to modal logic, especially since the development of possible world semantics.

In mathematics, a fact is a statement (called a theorem) that can be proven by logical argument from certain axioms and definitions.

A party (e. g., plaintiff) to a civil suit generally must clearly state the relevant allegations of fact that form the basis of a claim. The requisite level of precision and particularity of these allegations varies, depending on the rules of civil procedure and jurisdiction. Parties who face uncertainties regarding facts and circumstances attendant to their side in a dispute may sometimes invoke alternative pleading. In this situation, a party may plead separate sets of facts that when considered together may be contradictory or mutually exclusive. This seemingly logically inconsistent presentation of facts may be necessary as a safeguard against contingencies such as res judicata that would otherwise preclude presenting a claim or defense that depends on a particular interpretation of the underlying facts and ruling of the court.