Saussure's conception of linguistic science is one that encounters certain problems on its own theoretical terrain... With Saussure this difficulty arises chiefly from the conflict in his thinking between a realist conviction that linguistic science has to do with a well-defined object of study that should somehow - ideally - be set apart from all 'external considerations like those of history, cultural influence, political events, conquest, colonization, etc., and on the other hand his equally firm insistence that such an object is constituted in and by the very act of theoretical abstraction that brings it into being.
The crucial and revolutionary aspect of modern linguistics is Saussure's insistence on the primacy of relations and systems of relations. Here, Saussure's theory of language is an exceptionally clear expression of the formal strategies by which a whole series of disciplines, from physics to painting, transformed themselves in the late nineteenth and early twentieth centuries and became modern... It is relationships that create and define objects, not the other way around.
[Saussure] asserts that philosophers are generally wrong in this matter, as they look at language as if it were simply a matter of naming (like Adam giving names to the various animals). They are unaware, he says, of two important aspects: on the one hand that the most important function of language does not consist in designating things, but in relating and combining words in different ways; and on the other hand that language is continually moving and transforming itself.
The first of the basic principles to which Saussure refers is that the relationship between the signifier and the signified is arbitrary. The term "arbitrary," he points out, "should not imply that the choice is left entirely to the speaker." Rather it means that the signifier-signified relationship is "unmotivated"; that is, there is no "natural connection" or any intrinsic reason why a particular sound-image should be linked with a particular concept.
Before Saussure, linguists studied how languages developed over time. For Saussure this historical 'diachronic' tracing cannot grasp how things acquire meaning or function in the world. He maintained that language can only be understood relationally, by looking at the relationships between different parts as a 'synchronic' system.
Saussure's linguistic inquiry analyzed the social and collective dimensions of language. He was interested in the infrastructure of language. He believed that the rules governing the use of it functioned on an unconscious level... His ideas not only gained hold on the imagination of linguists, but also had a profound impact on philosophy, art, literature, and the social sciences.
Language as a system Saussure called 'la langue'. The actual manifestations of a language in speech he called 'la parole'... English utterances [parole], for example, are the only data the linguist has about the underlying system, the English langue. Saussure's fundamental notion was that for any words or speech acts to have meaning there must be a system that makes it possible to utter and understand them.
For Saussure the semiotic perspective was central to any serious study of language. "Is it not obvious," he wrote, "that language is above all a system of signs and that therefore we must have recourse to the science of signs" if we are to define it properly?
Saussure's major work was contained in 'Cours de linguistique', a collection of his lecture notes published by his students a few years after his death. It sets forth basic principles of what he called semiology - often referred to now as semiotics. Semiology is the study of signs.
The fact that Saussure himself did not publish a treatise that would have expounded his ideas on language and linguistics generated a host of ambiguities. While his writings on various aspects of Indo-European languages are clear and remain relevant to this scholarly branch of the study of languages, the substantial albeit necessarily incomplete notes his students took as he was teaching and the unfinished manuscripts he left are tentative, even sometimes confused and contradictory.