"Any psychology of sign systems will be part of social psychology - that is to say, will be exclusively social; it will involve the same psychology as is applicable in the case of languages"

Ferdinand De Saussure, a foundational figure in the field of semiotics and structural linguistics, presents a profound assertion about the social nature of indication systems in this quote. By specifying that any psychology of indication systems becomes part of social psychology, Saussure highlights the intrinsic connection between language and society. He recommends that indication systems, similar to language, are not solitary phenomena that exist in isolation; rather, they are deeply ingrained within the social structures that produce and utilize them.

Using "psychology of indication systems" implies the study of how indications operate in human cognition and habits. Saussure presumes that this study is naturally social. This perspective arises from the concept that indications derive their meaning and function from their place within a system of social interactions. Signs are approximate in nature, acquiring significance through shared social conventions. The interrelation amongst indications, users, and contexts forms the foundation of this social structure.

By incorporating sign systems into social psychology, Saussure highlights their dependency on collective understanding. Interaction through indications requires a shared arrangement on significance, which is negotiated and enhanced within a community. This common aspect highlights the essence of sign systems as instruments for social interaction and cultural transmission.

In addition, Saussure draws parallels in between indication systems and language, asserting that the mental principles suitable to language likewise pertain to sign systems. Linguistic signs are a subset of indication systems, exhibiting how significance is built through differences and relationships within a network of indications. Language, as one of the most intricate sign systems, reflects the shared cultural and social truths of its users.

In summary, Saussure's declaration underscores the social underpinnings of sign systems. By equating their psychology with social psychology, he restates the idea that meaning is collectively created and sustained, making indications an essential bridge in between individual cognition and social interaction.