Abstract. This essay pursues basic ontological categories. The strategy is to develop a sense of systematic ontology by crafting a series of increasingly sophisticated category schemes. We move from an austere scheme of physical particles and sets to the traditional categories of substance and attribute, to a modern view of modality and intentionality, to the distinction between formal and material categories, and various candidates thereof, to a notion of categorial “depth.” Along the way we keep an eye out for where mind or consciousness falls in each category scheme. This study indicates that a piecemeal ontology will not deal adequately with basic ontological structures, including the place of consciousness in the world. The methodological lesson to be learned is that the systematic organization of categories is crucial to the practice of ontology.

Segue. In previous essays we explored structures of consciousness and different types of ontology that might help to account for features of consciousness including its intentionality and its dependence on both neural activity and cultural background. In this essay we turn exclusively to the problem of developing a detailed category scheme that allows us to deal with a variety of structures of the world, including the fundamental ontological differences among causal relations in nature, intentional relations in consciousness, social relations in culture – and ultimately with the organization of very basic categories or modes-of-being, including dependence, intentionality, unity, and process.