Indexicality - Peirce's Trichotomy of Signs

Peirce's Trichotomy of Signs

C.S. Peirce elaborated three central trichotomies of sign. The first depends on whether the sign itself is a quality or an actual thing or a habit (tone, token, type, also called qualisign, sinsign, legisign). The second (icon, index, symbol) depends on the kind of reference to the denoted object. The third depends on the kind of reference which the sign will be interpreted as making. Most famous is the second trichotomy:

• Icon, also called a likeness or semblance: a sign that is linked to its represented object by some shared quality (which may vary from physical appearances, common actions, distinct sounds, etc.). An example of this would be the stick-figure pictorial representations of men and women on the door of a public restroom. This is iconic because it is meant to signify a man or woman through a simplified visual representation. An icon does not depend on an actual connection to its object (which may fail to exist) or on a habit of interpretation.

• Index: a sign that is linked to its object by an actual connection or real relation (irrespectively of interpretation), for instance, by a reaction, so as to compel attention, in a definite place and time. A simple example is an "Exit" sign which has an arrow pointing towards the exit. Smoke billowing from a house is an index for a fire inside.

• Symbol: A symbol represents its denoted object by virtue of an interpretive habit or rule that is independent of any shared physical quality, contextual contiguity, or lack thereof, with that which it denotes. A symbol consists in that rule. A word such as "horse" is an example of a symbol which, additionally, is specific to a particular language and prescribes the qualities of its instances, which, then, are noticeably arbitrary with respect to iconic qualities and indexical connections. Most spoken language (with the exception of instances of onomatopoeia like 'hiccup' and 'roar') is symbolic because it is arbitrary in those senses. For example, the English word "window" has no relation to any actual physical window. Peirce usually considered personal names and demonstratives like "this" to be indices, not symbols.