Conceived in strictly Peircean terms, iconicity is one of the three relationships in which a representamen (expression) may stand to its object (content or referent) and which may be taken as the ground for their forming a sign: more precisely, it is the first of these relationships,
Contrary to the indexical ground, which is a relation, the iconic ground consists of a set of two classes of properties ascribed to two different things, which are taken to possess the properties in question independently, not only of the sign relation, but of each other. Indexicality as such involves two things, and may therefore be conceived independently of the sign function, but iconicity should be possible to conceive independently even of the second thing involved.
The blackness of a blackbird, or the fact of Franklin being an American, to use some of Peirces own examples, can be considered iconicities; when we compare two black things or Franklin and Rumford from the point of view of their being Americans, we establish an iconic ground; but only when one of the black things is taken to stand for the other, or when Rumford is made to represent Franklin, do they become iconic signs. Just as indexicality is conceivable, but is no sign, until it enters the sign relation, iconicity has some kind of being, but does not exist, until a comparison takes place. In this sense, if indexicality is a potential sign, iconicity is only a potential ground.
| Pure iconicity, i.e. a potential ground (Firstness): | perceived properties of a thing (which may serve as a signifier or a signified) |
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| Iconic ground, i.e. a potential sign (Secondness): | perceived similarity between properties attributed to a thing which may serve as a signifier and a thing which may serve as a signified |
| Iconic sign (Thirdness): | iconic ground the constituents of which are joined by a sign function |
The most interesting arguments against iconicity were adduced by Arthur Bierman. According to the argument of regression, all things in the world can be classified into a set of very general categories, such as thing, animal, human being, etc., and therefore everything in the universe can refer to, and be referred to by, everything else. Thus, if iconicity is at the origin of signs, everything will be signs.
Franklin and Rumford are, as we know, potential signs of each other. In the case of other iconical signs, such as pictures, a conventional sign function must either be superimposed on the iconic ground, or the iconic ground must itself be characterised by further properties. Even in the former case, iconicity is still needed, not to define the sign, but to characterise iconic signs.
The term secondary iconicity designates an iconic relation between an expression and a content, which can only be perceived once the sign function, and a particular variety of it, is known to obtain; that is, our knowledge about the existence of a convention is a condition upon the discovery of the iconic ground. The problem then becomes how to account for the possibility of there being a primary iconicity, that is, a case in which it is iconicity itself that is the condition upon the discovery of the sign function, that which must be perceived for the sign relation to be known to exist.
| Primary iconicity | the perception of an iconic ground obtaining between two things is one of the reasons for positing the existence of a sign function joining two things together as expression and content |
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| Secondary iconicity: | the knowledge about the existence of a sign function between two things functioning as expression and content is one of the reasons for the perception of an iconic ground between these same things |
For a person looking at television, itself shown on his television set, or using a computer which is simulated on another computer, there must still be one screen, and an environment in which it is placed, which is a zero-level world, a world which is not indirect, at least not as indirect as the other parts. There is never any doubt that what is seen on the screen is a sign of something else (i.e., a signifier).