6.8.1 From rhetorical device to cognitive device

　 There are two positions on the function of metaphors. The classical view, as held by Aristotle, sees metaphor as a kind of decorative in addition to ordinary language, a rhetorical device that makes language use colorful. This view highlights the aesthetic function of metaphors. It sees metaphor as something outside normal language that requires special forms of interpretation from listeners/readers. They must depart from literal meaning, when it is detected as anomalous, and look for the intended meaning. This view is succinctly expressed by Searle (1979: 114):

Suppose he hears the utterance, “Sam is a pig.” He knows that cannot be literally true, that the utterance, if he tries to take it literally, is radically defective... The defects which cue the hearer may be obvious falsehood, semantic nonsense, violations of the rules of speech acts, or violations of conversational principles of communication. This suggests a strategy that underlines the first step: where the utterance is defective if taken literally, look for utterance meaning that differs from sentence meaning.

It is easy to see that metaphor is regarded as deviation from normal language use.

　 Another view of metaphor, which has become more influential in the past two decades, holds that metaphors are a cognitive device. An important underlying assumption is that our linguistic knowledge is part of general cognition and that linguistic categorization is a product of the human mind. According to this view, meaning is based on conventionalized conceptual structures. Semantic structure reflects the mental categories which are formed on the basis of experiences. Metaphor is an essential element in our categorization of the world and our thinking process.

　 Cognitive linguistics has shown that metaphor is not an unusual or deviant way of using language. The use of metaphor is not confined to literature, rhetoric and art. It is actually ubiquitous in everyday communication. It is estimated that 70% of English lexical meanings are metaphorical (Lakoff & Johnson 1980, Reddy 1979). Such common expressions as waste time, head of state, face of a watch, warm color, holes in our argument, etc, are all metaphors. They are so conventionalized that speakers may not be conscious of their being metaphorical. Yet, they are not only a way of expressing ideas, but a way of thinking. “Metaphor is not just a matter of language ... Human thought processes are largely metaphorical ... Metaphors as linguistic expressions are possible precisely because there are metaphors in a person's conceptual systems”. (Lakoff & Johnson 1980: 6)