In the history of semiotic ideas, there have been numerous attempts to define the sign, which can be grouped into two main types.
It is important to note that both types of definitions are found in the works of St. Augustine (De Doctrina Christiana), who made significant contributions to sign theory among ancient philosophers, as well as in the work of the giant of semiotic science, Charles S. Peirce.
The first type emphasizes the sign’s ability to be a substitute:
“Aliquid stat pro aliquo” (Something stands for something else). “Res praeter speciem quam ingerit sensibus aliud aliquid ex se faciens in cogitationem venire” (Something that, apart from the image it introduces to the senses, suggests something else about itself) (St. Augustine).
“A sign is something which, for someone, stands for something else in some respect or capacity”.
The second type of definition emphasizes the sign’s ability to generate meaning: “Non est signum nisi aliquid significat” (There is no sign unless it signifies something) (St. Augustine).
“Semiotics does not deal with any specific object, but with all ordinary objects insofar as they participate in the process of signification”. “For a sign, it is first of all necessary to establish what is designated. It can have meaning only for thought, not at all for the object”.
Obviously, both types of definitions are true but incomplete. Modern definitions combine not only the two qualities of the sign but also emphasize its ability to be interpreted.
A sign means something to someone—in this statement lie the three essential characteristics of the sign: to signify, to substitute something, and to be interpreted by someone.
As early as 1868, Peirce wrote:
A sign, as such, has three references: first, it is a sign for some thought which interprets it; second, it is a sign that signifies some object to which it is equivalent in that thought; third, it is a sign in some respect or capacity, which connects it with that object.
The concept of a sign is fundamental to semiotics. According to modern understanding, a sign is primarily an informational object.
It represents (substitutes) not itself but something else—some other object external to it (denotatum, referent, designated).
The sign serves to store, transmit, and receive information about the designated object.\
The sign is informative not in and of itself, but for someone—for the user (interpreter). The property of being a sign is not inherently intrinsic to the sign—it is ascribed to it by the user and for the purposes of the user.
