Understanding Ontological Levels

In this paper, I defend a multiplicative approach that distin- guishes statues from amounts of matter, political entities from physical ones, qua entities (e.g. John qua Alitalia passenger) from players (e.g. John), etc. I develop a theory of levels which is based on the primitive notions of level, parthood, and grounding (a kind of existential dependence) and that is used to characterize more specific relations like constitution, inherence, and abstraction. I neither aim to propose a 'defini- tive' theory of levels nor to commit to their ontological or conceptual nature. Hence, the adjective 'ontological' used in the title does not qualify the nature of the entities that belong to levels but the way the notion of level is characterized, i.e. in terms of general and philosophically well-founded notions. By keeping away from a purely realist attitude, I can then dis- cuss the adequacy of some alternative first-order theories to account for three puzzling scenarios.