The Sign (semiotics) reference article from the English Wikipedia on 24-Apr-2004
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Sign (semiotics)

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In semiotics, a sign is generally defined as "something that stands for something else, to someone in some capacity" (Marcel Danesi and Paul Perron, "Analyzing Cultures"). It may be understood as a discrete unit of meaning. Signs are not limited to words but also include images, gestures, scents, tastes, textures, sounds - essentially all of the ways in which information can be processed and communicated by any sentient, reasoning mind.

Signs are elements that can be related together logically in a variety of different ways. Within semiotics there are two general schools of thought on the nature of sign relationships: those that believe signs are reducible to dyadic logic, and those that believe that signs require triadic relationships.

Dyadic Signs

The dyadic definition tries to establish the dual nature of a sign (as expressed by Ferdinand de Saussure) where the sign is divided into the tangible part, called the signifier, and the conceptual part, the signified. It also posits the importance of both orientational and situational context in which a sign can mean - a sign has to mean something to someone for the notion of meaning to be relevant (if you like, an observer of the sign's meaning has to be present for the meaning to exist) and the way a sign means can change depending on the situation, culture and a few other variables.

Triadic Signs

Charles Peirce, a contemporary of Saussure, proposed a different theory of signs. Signs establish meaning by means of relating other signs together. He identified three distinct parts to a sign:

Peirce's triadic notion of signs requires that relationships between one sign and another have to be mediated by a third sign. In this view, the mediating sign is the only way to express the nature of the relationship between the signs. Excluding this third sign limits the possible relational expression to simple co-occurance or similarity.