In "Course in General Linguistics," Saussure described the way language represents ideas and objects. The "sound image" (or written word) is the signifier and the idea or object that the "sound image" represents is the signified. The combination of signifier "tree" and the signified thing or idea of a tree is called the "sign." Saussure also noted that the relationship between the signifier and signified, while necessary to convey meaning, is inherently arbitrary. In other words, there is no essential connection to the letters T-R-E-E and the tree itself. This is easily proved by the existence of other languages.
If the word (or sound of the word) does not have meaning in and of itself and its relation to the actual thing or idea, how does it have meaning? "Tree" means tree because of its relation (difference/similarity) to other signs. Therefore, "tree" means tree because we contextualize it. We, as a community agree that "tree" means tree and "forest" means forest and "is" means exists or dwells in a certain place. Saussure states:
The arbitrary nature of the sign explains in turn why the social fact alone can create a linguistic system. The community is necessary if values that owe their existence solely to usage and general acceptance are to be set up; by himself the individual is incapable of fixing a single value.
Without these particular connections between signifiers and signifieds and their overall connection to each other, "The tree is in the forest" would mean nothing. Therefore, meaning is constructed via this relationship among signs and their associations between signifiers and signifieds.
Saussure also distinguished between the abstract system (and rules) of language and the individual speech acts which enact language. The abstract rules he called "langue" and the speech acts he called "parole." He used the analogy of chess to illuminate this distinction. Langue is the system of chess, the rules of the game. Parole is that actual game as it is played. In comparison with language, Parole would be the individual utterances of the signs and langue would be the systemic way those signs interact and are related. Saussure focused on the langue, the system and rules of language, but he noted how changes occur at the level of parole.
So, Saussure also noted that a synchronic study of language can provide as much or more information than a diachronic study can. A synchronic study looks at a language at a particular time. A diachronic study looks at the changes of language over time. Prior to Saussure, most linguists favored a diachronic approach. Continuing with the chess analogy, Saussure wanted to develop a synchronic approach, looking at the state of a game at a particular time. For example, a Queen or a Bishop has different value at different times during the game. Although this synchronic approach (studying language at a specific time) seems like it would benefit a study of parole, Saussure still emphasized la langue, the system of language at that given time.
Since the relationship between signifier and signified is arbitrary, Saussure found it more effective to look at the relationships (difference/similarity and interaction) between signs and their roles in a language at a given time. He emphasized a synchronic approach at the more abstract, systemic level (langue).
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