Michele Paolini Paoletti

Downward causation is a widespread and problematic phenomenon. It is typically defined as the causation of lower-level effects by higher-level entities. Downward causation is widespread, as there are many examples of it across different sciences: a cell constraints what happens to its own constituents; a body regulates its own processes; two atoms, when they are appropriately related, make it the case that their own electrons are distributed in certain ways. However, downward causation is also problematic. Roughly, it seems to be at odds with specific scientific and/or epistemological desiderata: first and foremost, that everything can be reduced (one day or another) to the fundamental, micro-physical constituents and goings-on of the universe, so as to provide a unified explanation of everything and a unification of all the sciences " from the bottom ". Indeed, downward causation (if it is an irreducible phenomenon) introduces special causings not only at the higher levels, but also at the lower ones: if, in principle, we cannot fully understand what happens to the electrons without paying attention to the atoms (at the higher level) and we cannot fully understand what happens to the atoms by only paying attention to the electrons (at the lower level), there is no fully lower-level explanation for both higher-level and lower-level goings-on. In this introduction, we shall try to describe the prospects for downward causation in metaphysics and the philosophy of science. After having delved into the connections between downward causation, emergence and levels (§1), we shall discuss the irreducibility of downward causation (§2). We shall then briefly consider how specific metaphysical and epistemological assumptions bear on our understanding of downward causation and of its possibility (§3) and describe some views according to which downward causation is actually non-causal (or it is a special causal relation) (§4). We shall also mention some problems for the connection between downward causation and mental causation (§5) and some scientific examples of downward causation (§6). Finally, we shall summarize the contents of the contributions in this book (§7).