According to the method of production, signs can be classified as natural or artificial.
This division was first introduced by St. Augustine (354-430 AD):
Among signs, some are natural (natural signs), and others are given (artificial signs).
Natural signs are those which, without intention or desire to signify, convey something more beyond what they themselves are. For example, smoke signifies fire. It does so without any intention, but we know from experience, through observation and noticing things, that even if smoke appears on its own, there is fire beneath it. The track of an animal that passes also belongs to this type of sign. As for the face of an angry or sad person, it conveys the feeling of their soul without that person having any intention to express their anger or joy.
Given signs are those that all living beings make to each other to show, as far as they can, the movements of their soul, that is, everything they feel and think.
Our only reason to signify, that is, to make signs, is to make visible and convey to the mind of another that which is important in the mind of the one producing the sign.
The division of signs into natural and artificial is the only classification criterion on which semioticians have no disagreements.
Occasionally, minor nuances appear in the approach—such as the proponents of the communicative approach in semiotics, who use this division to distinguish between signs without communicative intent (“natural,” “unintentional,” and “unconscious”) and signs with communicative intent (artificially produced with the purpose of communication), which Buissance calls “semia,” and Prieto “signals.”
The division of signs into natural and artificial coincides with the two categories of signs that Umberto Eco distinguishes according to basic logical operations:
- 1st category of signs – the “substitution” relationship is built on the principle of implication: smoke implies fire, thunder implies a storm, fever implies illness, hoofprints imply the presence of a hoofed animal, etc.
- 2nd category of signs – here, there is a relationship of identity. The word “elephant” = the object elephant, the cross = the Christian religion, the symbol “♓” = the zodiac sign “Pisces,” etc.
Summary:
3.2.1. Natural signs
All signs produced naturally, unconsciously, and unintentionally by nature (by the physical environment and living organisms) are called natural signs.
3.2.2. Artificially created signs
Artificial signs are all signs produced consciously and intentionally. The aim of them being created is for them to be interpreted within a given society.
Therefore, they belong to organisms that have consciousness and live in a society that establishes their meaning through an explicit or implicit agreement (convention).
For this reason, these signs are also called conventional signs.