In his well-known essay "Two Aspects of Language and Two Types of Aphasic Disturbances" Roman Jakobson presents a theory of language based on certain empirical observations and discoveries. Jakobson examines aphasia, a disorder of language use, which he characterizes as consisting of two more fundamental types of disorder. These coincide with what he considers to be the bases and underlying processes of languages as such. These are the metaphoric and metonymic processes that govern all verbal activity and indeed even human behavior in general. Every case of aphasia involves an impairment of the metaphoric or metonymic activities, and every case exhibits at least one of these traits. Normally these two processes occur continuously and interactively in language, though the individual speaker places greater emphasis on one or the other in accord with his or her preferences and predilections. Metaphor and metonymy are the defining poles of language: all linguistic expression lies somewhere between these extremes.
Having identified these essential components of language Jakobson begins looking for further evidence to confirm his claim. He graduates his arguments to facilitate comprehension of the increasingly complex uses to which language is put. He considers, for instance, a normal but controlled use of language in a psychology experiment performed with children. When a group of children were presented with the noun "hut," their verbal responses invariably exhibited metaphoric or metonymic preferences. There was, in other words, no response other than in terms of metaphor or metonymy. This consequence bolsters the findings based on aphasia: the defining poles of language are metaphor and metonymy, and the individual preference (or predilection) determines the priority of one over the other.
Jakobson's theory is brief and concise, and is very much in accord with the concept of a definition prevalent in the natural sciences. But he is not content with these two pieces of evidence; he goes on to consider an uncontrolled use of language. One can gauge the depth of Jakobson's conviction when one notices that in focusing on an uncontrolled use of language he selects an exceptionally creative form--literature. If the theory can handle literature, then unquestionably it must be acceptable. Jakobson considers the literary schools of Romanticism, Realism, and Symbolism and shows how they relate to the metaphoric and metonymic poles. Citing examples of literary products of these schools he shows that they exhibit the same pattern as the aphasia patients and the children in the psychology experiment. From literature it is an easy step to other artistic forms like the cinema; and again one finds the same evidence of metaphoric and metonymic processes at work. Jakobson then makes the larger claim that the same is true of other semiotic systems and suggests that collaborative, interdisciplinary research be undertaken to explore the implications of his discovery fully. (1) Such research could be carried out, he suggests, by experts from the disciplines of linguistics, psychology, psychopathology, poetics, and semiotics (93). The depth of Jakobson's conviction is perhaps best stated in a remark he made in 1980: "A linguistic study of aphasia closely linked to the study of language in general and to poetic language in particular not only contributes to the classification of aphasic disorders, but also to the comprehension of the structure of language and even to the improvement of the methods of poetics" (Jakobson and Pomorska 134).
As an example of what might result from such research and as further evidence for the metaphoric and metonymic poles of language, Jakobson discusses the case of Gleb Ivanovic Uspenskij, a Russian novelist with a strong metonymic bent. Jakobson contends that Uspenskij's writings constitute a case in point of the predominance of metonymy in Realist literature. Uspenskij suffered in his later life from a mental illness that involved a verbal disorder. Since he displayed a metonymical bent in his literary works, one would expect to see this characteristic reflected in his verbal disorder--and that is what exactly happened. Uspenskij was unable to relate his first and patronymic names (Gleb and Ivanovic), a disorder bound up with the metonymical bent. This kind of psycholinguistic analysis of verbal behavior is only one area illuminated by Jakobson's discovery. Other dichotomies in human actions and expressions, too, can be interpreted in this light. For instance, Freud's theory of the structure of dreams, the principles underlying magic and ritual, and the differences between prose and poetry can all be explicated on the model of Jakobson's bipolar division operating in human processes.