Changes

==Origin==

==Origin==

French ''vague'' or [[Latin]] vagus wandering, inconstant, [[uncertain]], etc

French ''vague'' or [[Latin]] vagus wandering, inconstant, [[uncertain]], etc

*[http://en.wikipedia.org/wiki/13th_century 13th Century]

*[https://en.wikipedia.org/wiki/13th_century 13th Century]

==Definitions==

==Definitions==

*1a : not [[clear]]ly [[expressed]] : stated in indefinite terms <vague accusations>  

*1a : not [[clear]]ly [[expressed]] : stated in indefinite terms <vague accusations>  

*5: not sharply [[outlined]] : hazy <met by vague figures with shaded torchlights — Earle Birney>  

*5: not sharply [[outlined]] : hazy <met by vague figures with shaded torchlights — Earle Birney>  

==Description==

==Description==

The term '''vagueness''' denotes a [[property]] of [[concepts]] (especially [http://en.wikipedia.org/wiki/Predicate predicates]). A concept is vague:

The term '''vagueness''' denotes a [[property]] of [[concepts]] (especially [https://en.wikipedia.org/wiki/Predicate predicates]). A concept is vague:

*if the [[concept]]'s extension is unclear;

*if the [[concept]]'s extension is unclear;

*if there are objects which one cannot say with [[certainty]] whether belong to a [[group]] of objects which are identified with this [[concept]] or which [[exhibit]] characteristics that have this predicate (so-called "border-line cases");

*if there are objects which one cannot say with [[certainty]] whether belong to a [[group]] of objects which are identified with this [[concept]] or which [[exhibit]] characteristics that have this predicate (so-called "border-line cases");

*if the [http://en.wikipedia.org/wiki/Sorites_paradox Sorites paradox] applies to the [[concept]] or predicate.

*if the [https://en.wikipedia.org/wiki/Sorites_paradox Sorites paradox] applies to the [[concept]] or predicate.

In everyday [[speech]], vagueness is an [[inevitable]], often even [[desired]] [[effect]] of [[language]] usage. However, in most specialized [[texts]] (e.g., [[legal]] [[documents]]), vagueness is distracting and should be avoided whenever possible.

In everyday [[speech]], vagueness is an [[inevitable]], often even [[desired]] [[effect]] of [[language]] usage. However, in most specialized [[texts]] (e.g., [[legal]] [[documents]]), vagueness is distracting and should be avoided whenever possible.

Vagueness is [[philosophically]] important. Suppose one wants to come up with a [[definition]] of "right" in the moral sense. One wants a definition to cover [[actions]] that are clearly right and exclude actions that are clearly wrong, but what does one do with the borderline cases? Surely, there are such cases. Some [[philosophers]] say that one should try to come up with a definition that is itself unclear on just those cases. Others say that one has an interest in making his or her definitions more precise than ordinary [[language]], or his or her ordinary [[concepts]], themselves allow; they recommend one advances precising definitions.

Vagueness is [[philosophically]] important. Suppose one wants to come up with a [[definition]] of "right" in the moral sense. One wants a definition to cover [[actions]] that are clearly right and exclude actions that are clearly wrong, but what does one do with the borderline cases? Surely, there are such cases. Some [[philosophers]] say that one should try to come up with a definition that is itself unclear on just those cases. Others say that one has an interest in making his or her definitions more precise than ordinary [[language]], or his or her ordinary [[concepts]], themselves allow; they recommend one advances precising definitions.

Vagueness is also a [[problem]] which arises in [[law]], and in some cases [[judges]] have to [[arbitrate]] regarding whether a borderline case does, or does not, satisfy a given vague [[concept]]. Examples include disability (how much loss of [[vision]] is required before one is legally [[blind]]?), [[human]] life (at what point from [[conception]] to [[birth]] is one a legal [[human being]], protected for instance by laws against [[murder]]?), adulthood (most familiarly reflected in legal ages for driving, drinking, [[voting]], consensual [[sex]], etc.), [[race]] (how to classify someone of mixed racial [[heritage]]), etc. Even such apparently unambiguous [[concepts]] such as [[gender]] can be subject to vagueness problems, not just from [http://en.wikipedia.org/wiki/Transsexual transsexuals]' gender [[transitions]] but also from certain genetic conditions which can give an [[individual]] both [[male]] and [[female]] biological traits (see [http://en.wikipedia.org/wiki/Intersexual intersexual]).

Vagueness is also a [[problem]] which arises in [[law]], and in some cases [[judges]] have to [[arbitrate]] regarding whether a borderline case does, or does not, satisfy a given vague [[concept]]. Examples include disability (how much loss of [[vision]] is required before one is legally [[blind]]?), [[human]] life (at what point from [[conception]] to [[birth]] is one a legal [[human being]], protected for instance by laws against [[murder]]?), adulthood (most familiarly reflected in legal ages for driving, drinking, [[voting]], consensual [[sex]], etc.), [[race]] (how to classify someone of mixed racial [[heritage]]), etc. Even such apparently unambiguous [[concepts]] such as [[gender]] can be subject to vagueness problems, not just from [https://en.wikipedia.org/wiki/Transsexual transsexuals]' gender [[transitions]] but also from certain genetic conditions which can give an [[individual]] both [[male]] and [[female]] biological traits (see [https://en.wikipedia.org/wiki/Intersexual intersexual]).

Many [[scientific]] [[concepts]] are of [[necessity]] vague, for instance species in [[biology]] cannot be [[precisely]] defined, owing to unclear cases such as [http://en.wikipedia.org/wiki/Ring_species ring species]. Nonetheless, the concept of species can be clearly applied in the vast [[majority]] of cases. As this example [[illustrates]], to say that a [[definition]] is "vague" is not necessarily a [[criticism]]. Consider those animals in Alaska that are the result of breeding [http://en.wikipedia.org/wiki/Sled_dog Huskies] and [http://en.wikipedia.org/wiki/Wolf wolves]: are they dogs? It is not clear: they are borderline cases of [http://en.wikipedia.org/wiki/Dogs dogs]. This means one's ordinary [[concept]] of doghood is not clear enough to let us rule conclusively in this case.

Many [[scientific]] [[concepts]] are of [[necessity]] vague, for instance species in [[biology]] cannot be [[precisely]] defined, owing to unclear cases such as [https://en.wikipedia.org/wiki/Ring_species ring species]. Nonetheless, the concept of species can be clearly applied in the vast [[majority]] of cases. As this example [[illustrates]], to say that a [[definition]] is "vague" is not necessarily a [[criticism]]. Consider those animals in Alaska that are the result of breeding [https://en.wikipedia.org/wiki/Sled_dog Huskies] and [https://en.wikipedia.org/wiki/Wolf wolves]: are they dogs? It is not clear: they are borderline cases of [https://en.wikipedia.org/wiki/Dogs dogs]. This means one's ordinary [[concept]] of doghood is not clear enough to let us rule conclusively in this case.

One [[theoretical]] approach is that of [http://en.wikipedia.org/wiki/Fuzzy_logic fuzzy logic], developed by American mathematician [http://en.wikipedia.org/wiki/Lotfi_Zadeh Lotfi Zadeh]. Fuzzy logic proposes a [[gradual]] [[transition]] between "perfect falsity", for example, the [[statement]] "Bill Clinton is bald", to "perfect truth", for, say, "Patrick Stewart is bald". In [[ordinary]] logics, there are only two [http://en.wikipedia.org/wiki/Truth-value truth-values]: "true" and "false". The fuzzy [[perspective]] differs by introducing an [[infinite]] [[number]] of truth-values along a [[spectrum]] between perfect [[truth]] and perfect [[falsity]]. Perfect truth may be [[represented]] by "1", and perfect falsity by "0". Borderline cases are thought of as having a "truth-value" anywhere between 0 and 1 (for example, 0.6). Advocates of the fuzzy logic approach have included K. F. Machina (1976) and [http://en.wikipedia.org/wiki/Dorothy_Edgington Dorothy Edgington] (1993).[http://en.wikipedia.org/wiki/Vagueness]

One [[theoretical]] approach is that of [https://en.wikipedia.org/wiki/Fuzzy_logic fuzzy logic], developed by American mathematician [https://en.wikipedia.org/wiki/Lotfi_Zadeh Lotfi Zadeh]. Fuzzy logic proposes a [[gradual]] [[transition]] between "perfect falsity", for example, the [[statement]] "Bill Clinton is bald", to "perfect truth", for, say, "Patrick Stewart is bald". In [[ordinary]] logics, there are only two [https://en.wikipedia.org/wiki/Truth-value truth-values]: "true" and "false". The fuzzy [[perspective]] differs by introducing an [[infinite]] [[number]] of truth-values along a [[spectrum]] between perfect [[truth]] and perfect [[falsity]]. Perfect truth may be [[represented]] by "1", and perfect falsity by "0". Borderline cases are thought of as having a "truth-value" anywhere between 0 and 1 (for example, 0.6). Advocates of the fuzzy logic approach have included K. F. Machina (1976) and [https://en.wikipedia.org/wiki/Dorothy_Edgington Dorothy Edgington] (1993).[https://en.wikipedia.org/wiki/Vagueness]

[[Category: Logic]]

[[Category: Logic]]

[[Category: Languages and Literature]]

[[Category: Languages and Literature]]