The conventionality of metonymies: Salience, aptness and emergence
Cognitive linguists hold that metaphorical and metonymic expressions typical of everyday language are windows to the human mind: they allow us to find out how we conceptualise and understand the world around us. But even though current research clearly concentrates on so-called conventional examples, the meaning of the term 'conventional' has been more or less taken for granted, which led to different and partly contradictory classifications of conventionality.
Conventionality, I will argue, is a complex concept with different, interrelated facets on the linguistic and conceptual level and a major factor influencing the online processing of linguistic units. On the conceptual level, which will be the focus of my paper, the conventionality of figurative language is indisputably linked to well-entrenched conceptual patterns underlying and motivating it. As far as metaphors are concerned, Conceptual Metaphor Theory has proposed a number of criteria which allow us to distinguish different degrees of conventionality, notably among them unidirectionality, the distinction between commonly 'used' and 'unused' parts of the source, and the contrast between systematic mappings and idiosyncratic expressions. Additionally, psycholinguists have used the criterion of aptness, which basically relies on the conceptual distance of the domains involved and determines the comprehensibility of a given metaphorical expression to a certain extent.
Metonymy has come into the limelight of cognitive linguistics only recently so that the criteria are much less well-defined. I will point out that apart from the underlying conceptual mappings, the conventionality of a given metonymy is primarily affected by the different aspects of the notion of salience: Ontological salience or conceptual prominence is responsible for the preferred direction of mapping, and conceptually stable salient attributes of the source, that are often linked to encyclopedic knowledge, promote comprehensibility. Furthermore, some metonymic expressions exhibit changes in the relative salience of the attributes of the source concept, a phenomenon that will be shown to parallel the 'emergent structure' that Conceptual Blending Theory has for example described for metaphors. Taken together, these various aspects determine to a large extent if a speech community accepts a given metonymic expression as 'natural' and more or less 'literal', i.e. as a (sociopragmatically) conventional way of expression.