Emergence in Context: A Treatise in Twenty-First Century Natural Philosophy
Authors: Bishop Robert C. , Silberstein Michael 
Published: October 2023

EMERGENCE IN CONTEXT: A Treatise in Twenty-First Century Natural Philosophy by Robert C. Bishop, Michael Silberstein, and Mark Pexton. Oxford, UK: Oxford University Press, 2022. 363 pages. Hardcover; $103.65. ISBN: 9780192849786. *Reductionists dream of a day when all scientific truths can be derived from fundamental physics. Bishop, Silberstein, and Paxton show that dream is now dead, or at least it's quite ill. But what will replace it? One answer is "emergence," although that term is ambiguous. In its weak sense, it merely expresses pessimism about our ability to fully understand how microphysics produces all other phenomena. In its strong sense, it means that some entities have a kind of autonomy from physics, with their own "causal powers," including downward causation. Bishop et al. seek to replace strong and weak emergence with "contextual emergence." *Let's start with an example (sec 2.4). Rayleigh-Bénard convection occurs when a fluid is trapped between a heating plate below and a cooler one above. Convection cells emerge as warmer fluid rises toward the top and cooled fluid sinks. While molecular interactions play a part in this, sustained convection is impossible without the macroscopic plates. This behavior is not wholly determined by the fluid's constituent parts but rather by the context in which the fluid exists. *What this and scores of other examples show is that phenomena at a given scale often depend on a host of "stability conditions" at other scales--sometimes higher, sometimes lower. Contra the reductionist, the authors argue that the behavior of entities, properties, and processes at a given level is never wholly determined by events at a lower level. Macroscopic conditions (among other things) play an essential and ineliminable role. If we knew all the truths of nature, we would see that not all dependence is bottom-up. *"But the plates in your example are made of matter," says the critic, "We can reduce those to the behavior of atoms as well." A complete mathematical description without idealizations? "Well, it can be done in principle." Let's consider another example while we wait. Physicists in the Newtonian era devoted much time to the study of planetary orbits. One surprising stability condition is three-dimensional space. In four dimensions, regular orbits that resist small perturbations would be impossible (p. 29). Note that spatial dimensions are not part of the system. They are the context in which the system exists. Three dimensions are a necessary condition for stable orbits but cannot be reduced to the system's constituents even in principle. The properties of the parts do not determine the properties of the whole. This example illustrates why emergent properties are often inexplicable or unpredictable given complete knowledge of lower-level constituents: stability conditions are typically not at some lower level. While some stability conditions are causal and mechanical, like the plates in the convection examples, others are acausal, like conservation laws and least action principles. Still more are abstract properties of dimension and the geometry of mathematical spaces. Whichever the case, the authors consider those conditions to be as real or "fundamental" as anything at the level of elementary physics--something that sets this book apart from both reductionism and many other versions of emergentism. *Emergence is often associated with novelty, such as when a new and unexpected higher-level property emerges from its base. The authors believe this attention is misplaced. They focus instead on how stability conditions either open or close off areas of "possibility space." A possibility space is an abstraction in which each point represents a possible state or behavior of the system. For example, one point in the possibility space of a baseball represents its being in orbit--a possibility that will likely never be actualized. In Newtonian mechanics, the ball might also travel at the speed of light. Under special relativity, on the other hand, that part of possibility space is closed to the ball. As a result, no material object can reach that speed. The more interesting and neglected case occurs when stability conditions create access to parts of possibility space. For example, lasers do not exist in nature. Their stability conditions include the existence of a resonance cavity in which atoms can be electrically stimulated and isolated from their environment and putting those atoms in the proper state to begin the process (sec 4.9.1). When these conditions are in place, the area of possibility space representing coherent light becomes accessible. Such light has always been physically possible, but without the requisite context, it cannot become actual. *The authors make several applications to perennial questions in the philosophy of science that I do not have space to elaborate on. These include modality, dispositions/causal powers, properties, the laws of nature, causation, and determinism. Each of these has a relation to stability conditions that is often overlooked. The authors show how progress can be made on each question with less metaphysical baggage than many analytic metaphysicians assume. *Chapter 7 includes several possible objections, but one stands out. While we might need to use multiscale modeling in order to make predictions, that's because of our own epistemic limitations. Stability conditions are important, a critic might grant, but they are ultimately grounded in fundamental physics just like everything else. If we only knew enough about the system and its contexts, we would see how it's all due to the behavior of fields, particles, or whatever resides at the lowest level. *Bishop et al. reply that emergence has the evidence on its side, including an entire book with dozens of examples that cannot be reduced in the manner the critic envisions (p. 313). Nonetheless, the ontological reductionist continues to claim that while these examples have not yet been reduced to lower-level phenomena, it's just a matter of time. One wonders how long such promissory notes will be accepted. *My only concern is that contextual emergence might be too commonplace. Emergentists, especially of the strong variety, sometimes have difficulty providing convincing examples. Consciousness and quantum entanglement always make the list, but neither is fully understood. Contextual emergence, in contrast, is ubiquitous. Many examples are from biology and neuroscience, as one might expect, but most come from physics itself. Consider one more. Whether a dying star forms a white dwarf, neutron star, or black hole depends on its context, specifically how much mass the star had prior to collapse (sec 4.4). All three are therefore contextually emergent. But our hypothetical critic will surely complain that there's nothing emergent about this. The context is just mass, and mass is fundamental. Even some fellow emergentists might wonder whether calling every example that relies on necessary conditions "emergence" diminishes the significance of the term. Whatever the terminology, the book highlights a neglected aspect of what science tells us about the world. The objects and properties science studies depend on stability conditions, and those conditions are not typically found at smaller scales. Contextual emergence, therefore, stands in stark contrast to what reductionists had led us to expect. *Insofar as reductionism is incompatible with theism, this is the main takeaway for Christian academics. Science still tends to operate under a reductionist narrative that can deal with religious belief only in terms of psychological predispositions and sociological pressures. But if this narrative is false even in the physical sciences, then religious beliefs need not be restricted to such cramped corners. One might even wonder whether some of those beliefs are true. *Reviewed by Jeffrey Koperski, Professor of Philosophy, Saginaw Valley State University, University Center, MI 48710.