Horgan on the British emergentists

The British emergentists were not substance-dualists; they held that all particulars are physical entities wholly constituted out of physical entities as their parts. But they were not full-fledged materialists either, because they denied that physics is a causally complete science. They maintained that at various junctures in the course of evolution, complex physical entities came into being that had certain non-physical, "emergent", properties. These properties, they claimed, are fundamental force-generating properties, over and above the force-generating properties of physics; when such a property is instantiated by an individual, the total causal forces operative within the individual are a combination of physical and non-physical forces, and the resulting behavior of the individual is different from what it would have been had the emergent force(s) not been operative alongside the lower-level forces… Furthermore, there is no explanation for why emergent properties come into being, or why they generate the specific non-physical forces they do. These facts are metaphysically and scientifically basic, in much the same way that fundamental laws of physics are basic; they are unexplained explainers, which must be accepted (in Samuel Alexander's striking phrase) "with natural piety". Putative examples of emergent properties included (i) chemical-bonding properties of molecules, which were held to be emergent from physical properties of atoms or their constituents; (ii) self-maintenance and reproductive properties of living things, emergent from physical and chemical properties; and (iii) mental properties of creatures with consciousness, emergent from physical, chemical, and biological properties.¹¹