The second of the 2014 Loebel Lectures in Philosophy and Psychiatry, by Professor Kenneth S Kendler Since it is unlikely that we can identify a single causal level at which we can define our disorders etiologically, I explore the dappled causal world for psychiatric disorders, through an examination of psychiatric and other literature. I will suggest three primary and progressive goals for psychiatric research: to populate our causal space, to develop multilevel causal mechanisms, and to integrate the resulting neurobiological models with psychological explanations. I will consider how we might best conceptualise psychiatric disorders, and propose a new framework for how their classification might best move forward in time.