The grounds of the mass-count distinction, as well as the place and form of its expression in natural language, are central topics in current linguistic debates. What makes the complexity, and the particular interest of the mass-count distinction is that it applies at multiple levels, namely to the things in the world, to the way we conceptualise them, and to the expressions we use to refer to them. This distinction is thus multi-faceted, its different dimensions falling under the scope of philosophy (ontology and philosophy of mind), cognitive science (conceptualisation and language acquisition), and of course linguistics (semantics and syntax).

• Linguistics has long studied the syntactic and semantic structure of mass nouns (e.g. the water, the sand) as opposed to count nouns (e.g. a person, a table). There is indeed and important syntactic literature in this area, investigating the mass-count distinction in connection to issues of quantification, plural constructions, number modifiers and measure terms. On the semantic side, the mass-count distinction also raises important questions, such as the possibility to identify fundamental semantic properties characteristic of mass and count nouns respectively; the analysis of collective vs. distributive interpretations of constructions involving plural mass and count nouns; and the generic interpretation of such constructions.

• Philosophy, on the other hand, has, since its beginnings, reflected upon the ontological status of individuals and substances (primary vs. secondary substances in Aristotle); on the question of the priority of the one over the other; on their conditions of existence, of individuation and identity.

• Finally, experimental psycho-linguistics has recently taken over the debate on the mass-count distinction, and developed experimental settings aiming, for example, to understand the role of object recognition in the linguistic development and the lexicalisation of this distinction; or study the way and the age at which children learn to use generics, to individuate objects and to distinguish them from their composing substances.

The aim of this conference is to contribute to the establishment of new research avenues at the interface of these disciplines.

In particular, one of the implicit postulates of number of existing works seems to be that these different approaches and questions should somehow bring light to different aspects of one and the same "reality". It has thus been widely taken for granted that the linguistic distinction between count and mass nouns reflects a fundamental ontological reality, differences in semantic or syntactic behaviour being considered as a linguistic counterpart of the ontological division between substances and objects.  In the same vein, it is still a commonplace to think that the way in which we conceptualise the world reflects its profound structure, at least in its fundamental cleavages, our conceptualisation of reality acting as a bridge between the intrinsic nature of things and the way we talk about them.

However, recent research tends to question this "ideal" picture. It has for instance been shown that not all languages mark the mass-count distinction in the same way, or that nouns traditionally considered as count nouns can also have mass uses. Recent developments thus open new questions and new research avenues, and invite scholars to rethink the connection between the different dimensions of the mass/count distinction.

Furthermore, the study of constructions in which common nouns act as (quasi-)classifiers is expected to cast new light on the analysis of the mass/count distinction. Indeed, recent researches have started exploring the new perspectives opened by the study of such constructions, thus opening a whole new field of investigation. In particular, sortal nouns, measure and quantity nouns, but also "lighter" nouns like "the type" or "the kind" seem to play a reifying or discretising role. This invites a re-examination of the semantic role of nouns in the perspective of the mass/count distinction. Among others, it suggests a re-examination, under this new light, of the standard classification of nouns and their semantic role (beyond mere property attribution) depending on their sentence position.

It seems clear that these issues cannot be properly addressed without a true interdisciplinary dialogue, and this is precisely what this conference proposes. It aims to provide a platform of exchange, both intellectual and institutional, necessary for the apprehension of the new questions that are presently arising in connection to the mass/count distinction. This multidisciplinary conference will hopefully move this scientific debate forward, and contribute to the evolution of current methodology.