In
philosophy, the concept
fact is most commonly considered in the branch of philosophy concerned with knowledge and truth, called
epistemology, and possibly also under the branch called
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.
Correspondence and the slingshot argument 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.
Compound facts 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".
Fact–value distinction 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.
Factual–counterfactual distinction 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==