Peirce says: “We make observations of known signs, and then by ‘a process which I will not object to naming Abstraction’ are led to fallible (i.e. quasi-necessary) claims on the topic of what ‘must be.’ That abstraction is itself a kind of observation.”
In too many words to paraphrase, Peirce goes on to suggest something that should serve as an introduction to any discussion of semiotics: that we are so bound up in the acts of interpreting and signifying, that our common words for thinking about representation are inadeqaute for thinking about representation. To make really clear statements about signs, we cannot just say that a sign has certain features, and because of the arrangement and those features, has a meaning. We have to look at how signs operate upon each other, and how those operations work in time: turn backward, overlap, and co-exist with each other. Each of the nine terms below is best considered as an entity that emerges or appears in a process, rather than having a stable, immutable reality.
Signs are systems that have three parts or aspects: “the sign (itself)” (on which more immediately below), an “object” (the thing being signified), and an “interpretant sign” (a sort of means, or function, of interpretation, shared with other signs). Resist the urge to see these three aspects/parts of the signifying process as being fully independent categories—each is a potentially emergent issue affected broadly and loosely by the others. They are neither completely bound, nor completely independent; more like the parts of a windchime or a baby’s mobile, than separate knobs or switches on a user interface.
“The sign (itself)“—also called representamen, is what “brings something” to us, and is the thing that is interpreted in relation to something else.
“Idea”/”Object“—also called the representand, the thing (or “quasi-thing”) for which the sign actually stands. Objects can be “immediate” (and stable) or “dynamic” (in which a process occurs, as in the temperature indicated by a thermometer — any sign that one checks back on from time to time).
“Interpretant sign“—also called abstraction: for example, the effect of the sign on the mind (or a “quasi-mind”). Interpretants can be immediate (inherent?), dynamic (process of affecting an interpretation in a particular context), or final (full result of an interpretation). One interpretant can correspond to a thousand different images or actualities or fascimiles of an index finger pointing across the road, that is, they all have the same type of relationship to an object across the road.
To be a sign, in other words, the “sign (itself)” (1 above) has to relate to two other things: an interpretant that gives it a way of making meaning (2 above), and an object, that it stands for, or points to (3 above). An index finger, for example, signifies by implying a line that extends through the bearer’s forearm, down the finger, and through space (2 above), to connect that line to an object (3 above). A stop sign (1) signifies by the convention of red octagons, and the word “stop” (2), and by connecting that convention to an object: the point in a drivers’ procedure where stopping is required (3). Anything in the world that has these two kinds of relationships with the world is a sign.
In turn, each of these aspects or parts of the sign can function in three different ways:
THE SIGN ITSELF:
QUALISIGN—that an aspect or quality or state of a thing is what does the work of signifying. Think of the octagon, and the red, formed by a stop-sign, as qualities that act in a representational manner, together.
SINSIGN—that a fact or actuality or thing is what does the work of signifying. The presence of a stop sign commands a process: stop, look, then go. Its actual location tells you where to stop.
LEGISIGN—that a law, a tedency, a norm, or an ongoing action/process/behavior (with emphasis on the word ongoing) is what does the work of signifying. The patterns of presences and absences of stop signs among a variety of street corners communicates a pattern of stopping and going that each driver interprets in connection with other drivers.
THE MANNER OF RELATION TO ITS OBJECT:
ICON—via resemblance, a sign that “looks like”, “sounds like”, or “simulates”. The upward-pointing hand, faced palm toward you, is meant to keep you from moving forward, or to prevent your movement through a crosswalk; it does so because it resembles a person stopping you physically. Yellow can resembles fire in a “flammable” warning. An icon on a computer desktop usually resembles the file or application to which it points.
INDEX—via physical connection, spatial/temporal connection, or connection via orientation; a sign that “points.” A pronoun can be an index for its capacity to point (via temporal connection) to a noun. An index finger points across a road to an object that an interpreting mind is meant to call into consciousness. An index in a book points from concepts in an organized list, next to signifying page numbers, via spatial connection to the page itself, a reference to the listed concept.
SYMBOL—via convention; a sign that is established in a vocabulary of arbitrary signifiers, and is put to use in cultures or specialized subcultures outside of which the sign would not function. With few iconic exceptions, words and numbers are symbols of what they mean. X marks a spot, a checkerboard flag symbolizes the winner in an automobile race.
THE MANNER OF RELATION TO ITS INTERPRETANT:
RHEME—when a sign is “term-like”, standing to its interpretant via its quality. The octagonality and redness of stop-signs are rhemes; they are the qualities of an individual stop sign that connects it to the “stop interpretant”.
DICISIGN—when a sign stands to its interpretant in respect of fact, or actuality.
ARGUMENT—when a sign stands to its interpretant in respect of “habit or law.”