Emergence and Demergence
Rani Lill Anjum and Stephen Mumford
Make no mistake; emergence matters. It matters in medicine, for instance, where it could support the idea of an intervention at a relatively high level in order to improve a health problem at a lower level. One might reasonably make a lifestyle adjustment, then, aiming to alleviate digestive difficulties or high blood pressure.
Because metaphysics is often understood as lacking empirical content, it could be thought that it is irrelevant for science. However, this is certainly not the case with the question of whether there are emergent phenomena. If there are higher-level emergent properties, capable of downward causal influence, then it matters for how we relate to the world. It justifies the thought that you could intervene on factors such as stress in order to produce, through downward causal influence, desired changes at lower levels. Thus, the possibility of emergence is relevant to the question of whether a chemical imbalance causes depression or depression causes the chemical imbalance.
There is plenty of evidence of emergence in a variety of sciences and not just medicine (Ellis, Noble and O’Connor 2012). Indeed, one could argue that it is assumed in almost every action we perform as agents. We go to lift a chair, for example, rather than its molecules. Molecules are not the sort of thing we can intervene upon, except in special laboratory conditions, but it seems that we can interact with macro-level phenomena and thereby change the position of an assemblage of molecules. That is just the practice, however. The problem has always been how emergence works in theory, and how it does so without wreaking havoc upon a fairly successful way of understanding the world. There is an idea that all other sciences rest on, and are ultimately explained in terms of, fundamental physics. Emergentism is often seen as at odds with this because it tells us that the bottom level isn’t everything that matters.
Until we can provide a philosophical vindication of emergence, there will always be some scepticism about the idea of distinctly higher-level phenomena. A key task is to understand exactly what is being asserted by the emergentist and thus what is being denied by the reductionist. Our aim in this paper is to provide a good answer to that question. We also accept that some account is owed of how emergent phenomena arise; that is, we accept the objection from bruteness (e.g., Strawson 2008: 65). There has to be some intelligible sense in which emergent phenomenon, E, emerges from its base-level phenomenon, B, rather than from anything else; or that E is just free floating (as in forms of substance dualism). The emergence of E cannot be just a brute fact.