Strong emergence

A crucial question for both philosophy and for science concerns the kind of relationship that obtains between entities—objects, properties, states, processes, kinds and so on—that exist at apparently higher and lower ‘levels’ of reality. According to reductionism, seeming higher-level entities can in fact be fully accounted for by more fundamental, lower-level entities. Conversely, emergentists of various stripes hold that whilst higher-level entities depend in some important sense on lower-level entities, they are nevertheless irreducible to them. This introductory paper outlines the context of the debate between emergentists and reductionists; offers a broad characterisation of ‘strong’ or ontological emergence, and provides summaries of each of the papers to come in this special issue. 6 A. D. CARRUTH AND J.T.M. MILLER 1. The structure of inquiry and the structure of the world Part of the job of scientific inquiry is to engage with, make sense of, describe, explain and make predictions concerning the wildly varied phenomena which constitute the world around us. As a consequence of this aforementioned variety, distinct disciplines each with their own intellectual regimes—domains of inquiry, basic assumptions, investigative techniques and so on—address different groupings of this phenomena. Thus, physics, or at least an important part of that discipline, is concerned with the properties of and interactions between the relatively small and simple constituents of matter, and of energy. Chemistry addresses more complexly structured systems of those constituents that form substances—in the standard, as opposed to technical metaphysical, sense: elements, compounds, mixtures, suspensions and so on. Biology treats phenomena which exhibit the characteristics which are criterial for life, ranging over micro-organisms, flora, fauna etc. Psychology and cognitive science engage with just those living things which possess mentality, and sociology, economics and political science all range over aspects of the interactions between these thinking agents. These characterisations are somewhat glib, and they surely fall short of a properly nuanced and comprehensive conception of each discipline, but hopefully they are fit for the illustrative purpose to which they are employed. That inquiry has this sort of structure raises a number of interesting philosophical questions. One such set of questions concerns the sorts of relationships that obtain between the theories put forward by each discipline. Another set of questions concerns the extent to which the sort of structure described above is a feature not just of the way we organise our inquiry into the world, but of the world itself: that is, addressing the