self-evidence
{{Short description|Epistemologically probative proposition}}
{{more citations needed|date=December 2023}}
In epistemology (theory of knowledge), a self-evident proposition is a proposition that is known to be true by understanding its meaning without proof,{{Citation needed|reason=Reliable source needed for the whole sentence|date=August 2014}} and/or by ordinary human reason.
Some epistemologists deny that any proposition can be self-evident. For most others, one's belief that oneself is conscious and possesses free will are offered as examples of self-evidence. However, one's belief that someone else is conscious or has free will are not epistemically self-evident.
The following proposition is often said to be self-evident: "A finite whole is greater than, or equal to, any of its parts".
A logical argument for a self-evident conclusion would demonstrate only an ignorance of the purpose of persuasively arguing for the conclusion based on one or more premises that differ from it (see {{Lang|la|ignoratio elenchi}} and begging the question).
Analytic propositions
It is sometimes said that a self-evident proposition is one whose denial is self-contradictory. It is also sometimes said that an analytic proposition is one whose denial is self-contradictory. But the concepts mean different things, i.e., an analytic proposition is not always a self-evident proposition. {{explain|date=October 2015}}
Provided that one understands and believes a self-evident proposition, self-evident propositions are not in need of proof. Likewise, that their denial is self-contradictory does not need to be proven. It is in this sense that the self-contradictions at work in self-evident and analytic propositions are different.
Not all analytic propositions are self-evident, and it is sometimes claimed that not all self-evident propositions are analytic: e.g. my knowledge that I am conscious.
Other uses
=Informal speech=
In informal speech, self-evident often merely means obvious, but the epistemological definition is stricter.
=Moral propositions=
Moral propositions may also be regarded as self-evident, although the is–ought problem described by David Hume considers that there is no coherent way to transition from a positive statement to a normative one.
For example, Alexander Hamilton cited the following moral propositions as self-evident in the Federalist No. 23:
- The means ought to be proportioned to the end.
- Every power ought to be commensurate with its object.
- There ought to be no limitation of a power destined to effect a purpose which is itself incapable of limitation.
A famous claim of the self-evidence of a moral truth is in the United States Declaration of Independence, which states, "We hold these Truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness."; philosophically, these propositions' self-evidence is debatable.
= Mathematics =
In mathematics, self-evident refers to statements that need no proof. Sometimes axioms are described as self-evident.{{Cite web |last=Maddy |first=Penelope |date=1988 |title=Believing the Axioms |url=https://math.berkeley.edu/~kpmann/Axioms.pdf |website=Journal of Symbolic Logic}} Other statements are self-evident because the statement is a proof for itself.{{Citation needed|date=October 2023}}.
See also
{{Wiktionary|self-evidence}}
- {{slink|1=2 + 2 = 5|2=Self-evident truth and self-evident falsehood}}
- Axiom
- Contradiction
- Foundationalism
- Introspection
- Law of identity
- Primitive notion
- Self-reference
- Self-refuting idea
- infinite regress