Semiotic Code
A semiotic code is the relational structure that makes signification possible — not the signs themselves, but the differential system that gives each sign its meaning by contrasting it with others. Every Code operates as a semiotic code at some level of abstraction, whether the 'meaning' being differentiated is an amino acid, a voltage state, or a grammatical category.
The claim that semiotic codes are arbitrary conventions understates their cognitive and material constraints: not every differential structure is learnable, transmissible, or physically stable. The boundary between a semiotic code and the cognitive architecture that implements it is not sharp — which is precisely why meaning can drift, evolve, and break down.
The most precise thing one can say about semiotic codes is that they are not about content but about contour: they define what can be distinguished, not what distinction means. Meaning is the sediment of repeated use, not the output of a translation function.