Anjan Chakravartty and I are both scientific realists and yet we are separated by a great divide. He’s a neo-Aristotelian, whereas I am a neo-Humean. Prima facie, this is not a divide that has anything to do with scientific realism itself. It’s a divide within metaphysics—or the metaphysics of science, to be more precise. It might be thought that neo-Humeanism is anti-metaphysics altogether, but this is wrong. Metaphysics—that is, a view about the deep structure of reality and its fundamental constituents—is not optional. The only serious issue, I believe, is how deeply this view should be digging; how rich the conception of the fundamental structure of reality ought to be. Neo-Humeanism promotes a rather thin—or sparse—view of the fundamental structure of reality. In particular, it denies that the regularity there is in the world needs grounding in a metaphysically distinct (and typically deeper) layer of facts or entities, which are supposed to enforce the regularity there is in the world. But buying into the idea that the world is characterised by regular patterns of co-existence and succession of property-instances is metaphysics enough! So the real issue between neo-Aristotelianism and neo-Humeanism is not: metaphysics or notmetaphysics. Rather, it is: how much of metaphysics ought we to buy into? I take it that this question is elliptical and needs supplementation: how much of metaphysics ought we to buy into if we are to make sense of the world as this is described by science? Others might disagree with the suggested supplementation. Fair enough! In my own view, metaphysics should be in the service of science and should be constrained by it. I trust this is something Chakravartty and I share. Our disagreement (and the real disagreement between neo-Aristotelianism and neo- Humeanism) concerns precisely the issue of whether the image of the world as painted by modern science does require or imply a neo-Aristotelian metaphysics. Concomitantly, the issue is how we decide (philosophically) what kind of metaphysical theory is required by science...