The aim of the Metascience project is to make a significant contribution to the metaphysics of science on the basis of the detailed analysis of key concepts in current experimental sciences, above all physics, biology and psychology. We understand “metaphysics of science” as the field of research whose objective is the analysis of the fundamental concepts structuring scientific research – e.g., those of individual, cause, or disposition. Our strategy is best understood in contrast with the dominant perspective in today’s metaphysics. Indeed, most research presently done within this field proceeds by pure conceptual analysis. This strategy of philosophical research is sometimes explicitly stated and defended. It corresponds to what Strawson (1959) has called “descriptive metaphysics,” which aims at making explicit the conceptual structure underlying common sense. The method appropriate for this aim is the conceptual analysis of ordinary language statements and the intuitions they express. This approach structures, e.g., a large part of the research on causation. Most of the debates on the various attempts to analyze the concept of causation are framed by the search for so-called “counter-examples”: philosophical accounts of causation are evaluated by comparing the judgment they yield in various situations to the intuitive judgment on that situation. If the theory yields a result that contradicts naive intuition, the intuitive judgment is considered to be a counter-example to the theory. To the extent that common sense ignores scientific knowledge, science is irrelevant to the task of descriptive metaphysics. This project develops a completely different type of metaphysical enquiry. Our main interest does not lie in the analysis of the conceptual structure underlying common sense. Instead, our aim is to uncover the conceptual structure that underlies scientific theories and practice. To the extent that science often goes against common sense, to choose as our main criterion of adequacy agreement with science, not common sense, makes our approach belong to Strawson’s category of “revisionist metaphysics.” Indeed, our suggestion is that experimental sciences can offer an “image of the world,” which may well conflict with the layman’s image of the world, based mainly on our perceptions and intuitions. To take just one example, if the concept of the individual at work in biology includes within an individual organism all the microorganisms that live in symbiosis with it whereas common sense excludes them, we will ignore the latter and take seriously the former. More generally, our project aims at analyzing scientific concepts at work in science, even if they clash with commonsense ontology. When clashes do occur, our objective will be to spell out how and why. What is most distinctive of this project is our multidisciplinary approach to experimental sciences: our aim is to analyze various metaphysical key concepts by evaluating their role in structuring and accounting for scientific activities in more than one discipline. With some rare exceptions, almost all research in the metaphysics of science takes into consideration only one science, most usually physics. In contrast, we believe that comparing the roles a concept plays in different sciences may reveal its basic structure and features more reliably than an analysis that remains limited to a single discipline. The Metascience project is structured around three axes. Our strategy consists in analyzing the role played by three key notions in today’s experimental sciences: 1) levels of reality, 2) objects or individuals, and 3) dispositions. On the basis of this analysis, our aim is to draw conclusions on the structure of reality according to its scientific representation, on possible conflicts between the scientific representation of the world and the commonsense worldview, as well as on the makeup of our conceptual system.