What Is Emergentism?

Direct Answer

Emergentism is the thesis that when physical systems reach a sufficient level of complexity, genuinely new properties come into existence — properties that are not reducible to, predictable from, or explicable solely in terms of the properties of the system's parts. In the philosophy of mind, the paradigm emergent property is consciousness: the subjective, qualitative character of experience is held to emerge from the enormously complex organization of the brain, much as liquidity emerges from the arrangement of molecules or a tornado's behavior emerges from the dynamics of air and water — except that in the mental case, the emergence is claimed to be genuinely novel rather than merely a matter of description.

The key distinction is between weak emergence and strong emergence. Weak emergence is uncontroversial: a property or pattern is weakly emergent when it is unexpected or difficult to compute from the parts, even though it is in principle fully determined by them. Traffic jams, flocking birds, and the weather are weakly emergent: they are striking patterns produced by simple local rules, but they add nothing new to the world's ontology. Strong emergence is the philosophically loaded claim: a property is strongly emergent when it has novel causal powers of its own — when the emergent property does things that cannot be accounted for by the properties of the parts, and when the whole system behaves differently because of the emergent property. Classical emergentists, and many contemporary defenders of the reality of consciousness, claim that consciousness is strongly emergent: it is a new feature of the world with its own causal influence, supervening on the brain but not reducible to it.

To see the difference, compare a computer simulation and a mind. The simulation of a hurricane produces no wet wind; it is a pattern in transistors, and everything it does is fully accounted for by transistor physics. If consciousness is weakly emergent, it is like the simulation — a way of describing brain activity, but nothing more. If consciousness is strongly emergent, it is like the actual hurricane in the minds of the emergentists: something genuinely new that the organized system brings into being.

Historical Context

Emergentism flourished in the late nineteenth and early twentieth centuries, especially in Britain, as a scientifically minded alternative to both mechanical reductionism and vitalism. The British emergentists — John Stuart Mill, George Henry Lewes (who coined "emergence" in this sense), C. Lloyd Morgan, Samuel Alexander, and C. D. Broad — argued that chemistry and biology exhibit levels of organization in which higher-level properties arise from lower-level configurations in ways that could not have been predicted in advance. Broad's classic example was the emergentist treatment of chemistry: before the fact, one could not deduce the properties of a chemical compound from the properties of its elements alone.

In philosophy of mind, the emergentists offered a naturalistic account of consciousness: mind is not a separate substance (contra dualism) but arises from matter organized in a certain way (contra reductionism). Morgan's principle — "in a certain sense everything is emergent" — captured the layered picture: physics gives rise to chemistry, chemistry to biology, biology to mind.

The view declined mid-century under the pressure of logical empiricism, which dismissed unanalyzable "emergent laws" as mysterious, and with the rise of behaviorism and functionalism, which had no need for nonphysical mental properties. But the hard problem of consciousness revived it: by the 1990s, philosophers such as John Searle were defending a version of emergentism ("biological naturalism") in which consciousness is a real, causally efficacious feature of the brain that is nevertheless not reducible to lower-level neurophysiology.

Key Arguments & Debates

The main argument for emergentism about consciousness is the explanatory gap. If no physical account of the brain, however complete, seems to explain why there is subjective experience, then it is natural to conclude that experience is a genuinely new phenomenon — something that arises from complexity but exceeds any description of the parts. The irreducibility of qualia (the felt quality of experience) to physical facts supports the claim that mental properties are emergent rather than identical to physical properties.

A second argument is causal: consciousness appears to matter. Our experiences inform our judgments, guide our choices, and shape our behavior. If consciousness were epiphenomenal or merely identical to brain states described physically, its felt quality would be doing no explanatory work. Emergentists conclude that the phenomenal character of experience has novel causal powers — a form of "downward causation" in which higher-level mental states influence lower-level physical processes.

The objections are formidable. The most famous is the "causal exclusion" argument, associated with Jaegwon Kim: if every physical event has a complete physical cause (the causal closure of physics), then a strongly emergent mental property either duplicates the causal work of the physical — in which case it is causally redundant — or interferes with physical causation — in which case it violates physical laws. Either way, strong emergence seems to conflict with the scientific picture of a causally complete physical world. A second objection is that emergentism is a mystery-mongering doctrine: claiming that properties are "not explicable" from their bases looks like giving up on explanation rather than achieving it. A third is that emergence threatens to collapse into property dualism: if mental properties are irreducibly nonphysical features of reality, that is just property dualism under a different name, with all the same problems.

Defenders respond that the causal closure principle is an assumption, not a proven result; that downward causation can be understood without violating physics; and that emergence is not a retreat from science but a description of what science itself reveals about the organization of nature.

Contemporary Relevance

Emergentism is central to current debates about consciousness and AI. In neuroscience, the concept of "emergence" is routinely used to describe how perception, cognition, and consciousness arise from large-scale brain dynamics — even when the philosophical commitments of the researchers are left unspecified. The question of whether a sufficiently complex artificial neural network would "light up" with experience is precisely a question about whether consciousness is strongly emergent or merely functional. If consciousness is strongly emergent from biological complexity, silicon systems might never achieve it; if it is weakly emergent or functional, they might.

The view also matters for the ethics of AI and animals: whether an entity's inner experience is an irreducible emergent reality (deserving moral consideration) or a useful description (potentially absent in systems that merely simulate it) determines how we should treat sophisticated machines and how seriously we should take the consciousness of non-human animals.

Related Concepts

• Supervenience: the formal relation emergent properties bear to their physical bases.
• The identity theory: the reductive alternative emergentism rejects.
• The hard problem vs easy problems: the explanatory gap that motivates strong emergence.
• Panpsychism: the alternative to emergence that treats consciousness as fundamental rather than arising.
• Phenomenal consciousness: the property claimed to be emergent.
• Neutral monism: a monistic alternative that avoids emergence entirely.

Further Learning

• Stanford Encyclopedia of Philosophy: Emergent Properties
• Internet Encyclopedia of Philosophy: Emergentism
• C. D. Broad, The Mind and Its Place in Nature (1925).
• John Searle, The Rediscovery of the Mind (1992).