The project is structured around three research directions, aimed at understanding i) how the process of building ad hoc categories is expressed across languages, ii) how the strategies employed for this functions develop and iii) what are the functions and patterning of ad hoc categories in discourse (see section 1). In order to reach these three goals, three different, though closely connected, methodologies will be adopted.
The leading idea is that, in order to provide a comprehensive picture of how ad hoc categorization is performed in discourse and across languages, it is necessary to use evidence coming from different fields and through complementary methodologies.
The results achieved in one risearch direction are at the same time test-beds for the hypotheses developed in the others (see Research Directions). The analysis of universal tendencies and cross-linguistic variation will lead to an explanatory account, aimed at understanding the reasons underlying the limits of cross-linguistic variation. Such explanations will be based on extra-linguistic principles. In the typological literature two main types of factors are argued to explain universal tendencies: i) diachronic processes and ii) patterns (especially frequency) of use in discourse, which may be crucially verified in the two complementary research directions. In turn, diachronic change is typically triggered by frequent patterns of use in discourse (Bybee 2005). Conversely, behind distributional and functional variation in discourse, it is often possible to see the reflections of successive diachronic stages, or the emergence of new constructions (Croft 2010).