Special Issue: Linguistic strategies for the construction of ad hoc categories: synchronic and diachronic perspectives

Ad hoc categorization is the bottom-up abstraction of a category starting from concrete exemplars of the category itself. When we observe linguistic data, we find various phenomena that provide evidence for the ubiquity of such an on-line, goal-driven and context-dependent categorization in everyday communication. Beyond offering concept labels in the form of words, language indeed provides speakers with a great number of strategies to convey reference to a class by naming representative individuals. After providing a semantic and pragmatic account of ad hoc categorization in terms of indexicality, we will survey ad hoc categorization strategies in discourse and across languages: they can be syntactic (lists, general extenders, exemplifying constructions), morphological (heterogeneous plurals, collectives, aggregates, compounds), or in-between (reduplication). We will argue that all these strategies show a similar abstract structure consisting in a categorization trigger, that is, some prosodic, morphological or syntactic element triggering the abstractive inferential process towards the category identification, plus a linguistic expression referring to some overt category member, which is processed as the starting point for abstraction. The diachronic connections between these strategies and the pathways leading to their emergence and conventionalization also speak in favor of their unified treatment.