Specifically, a feature of or process within a macro-system is weakly emergent just in case it is derivable from the prior micro-facts leading up to it, but only in an informationally incompressible way: describing its macro-state at prior times by aggregating all of its underlying micro-states at those times and iterating their micro-dynamics.
It is possible to see special cases, giving rise to distinct species of weak emergence, within the broad framework of non-linear dynamics. This often takes the form of rejecting physical realization, affirming fundamental higher-level causal powers, or both. Perhaps the most commonly cited phenomena offered as requiring strong emergentist treatment have to do with the nature and capacities of the conscious mind in relation to its neural substrate.
Other non-mental, scientific phenomena also have been advances as possibly or plausibly requiring treatment in strong emergentist terms. Such claims are canvassed in section 5. This section introduces three commonly pressed challenges to the in-principle viability of strong emergence. Possible replies are noted in connection with certain accounts of strong emergence introduced in the subsequent section. An initial worry about strong emergence is that there is a tension in the very idea of a feature that is both dependent and fundamental—a worry exacerbated by recent accounts of fundamentality according to which what it is to be fundamental is precisely to be independent see Bennett and entry on fundamentality.
Granting that there is no incoherence in the idea of a non-basic, fundamental entity or feature, one might be concerned that such an entity or feature would introduce an inexplicable since fundamental addition to reality at an arbitrary juncture.
Avoiding such inexplicability might give reason to prefer a panpsychist accommodation of the irreducibility of consciousness to physical properties, as it unlike strong emergence posits proto-conscious qualitative character into the basic structure of the world Nagel and Strawson The notion of a strongly emergent force or energy is no more problematic than that of the standard physical forces or energies that physicists take to be input into the operative laws McLaughlin The real problem here, if there is one, is not inconsistency with physics, but rather that there is at present a lack of clear empirical evidence for strong emergence.
If there were strongly emergent causal powers, forces, or laws, we might expect to see, in candidate emergentist contexts, evidence for a hitherto unrecognized configurational interaction, much as occurred with the weak nuclear interaction. For strong emergentist replies to this contention, see section 4. On another version of the objection, certain ways of assigning powers to features entail that lower-level physical features will inherit any powers had by purportedly strongly emergent features Kim A metaphysically minimalist characterization of strong emergence is supervenience-based.
In contrast to weakly emergent or physically reducible features, which are taken to supervene with metaphysical necessity on their physical dependence base, strongly emergent features are taken to supervene with merely nomological necessity van Cleve , Chalmers , Noordhof This approach assumes that the conceptual distinction between nomological and metaphysical necessity corresponds to a substantial one, such that fundamental causal laws are metaphysically contingent and what supervenes of metaphysical necessity on the fundamental physical domain is necessarily physical.
Both these assumptions have been challenged. Moral anti-naturalists such as G. Moore maintain that fundamental moral features supervene of metaphysical necessity on natural features, and on neo-Aristotelian essentialist ontologies, strongly emergent features, were they to exist, would supervene with metaphysical necessity on physical features. See, however, Howell and Noordhof for strategies aimed at defending supervenience-based approaches to strong emergence.
One variant of this approach is epiphenomenalist Jackson , Kim , and Chalmers all express sympathy for this view. It presumes that the most plausible candidates for strong emergence are the qualitative features of conscious experience—e.
Epiphenomenal strongly emergent features are consistent with physical causal closure. For this reason, the account is less vulnerable than standard accounts to the objection that it entails presently unsupported empirical predictions about brain processes.
It is still incompatible with physicalism, since strongly emergent qualia are not physically realized, and so are wholly additional to token lower-level physical phenomena. A potential advantage of the approach is that it might capture the common denominator to all other, more distinctive accounts of strong emergence.
A corresponding shortcoming is that its high level of abstraction leaves it without the resources of more specific accounts for addressing the general challenges facing strong emergence noted above Paolini Paoletti and Pearson One variation on this basic account concerns the way emergents depend on their bases. This alternative can allow that, even granting that causal necessity is a species of metaphysical necessity, the supervenience of strongly emergent features on base phenomena will fail in at least possible scenarios in which the causal dependence between either base and emergent features or emergent features and their effects is non-deterministic.
That said, whether supervenience does in fact fail for any actual cases of strong emergence is an empirical question on which, see section 5. The fundamental powers account of strong emergence is consistent with a range of replies to the challenges noted in section 4. One reply is simply to observe that in the history of physics itself there is precedent for adding new fundamental laws to explain what previously recognized laws could not e.
When determining the fundamenta of the natural world, we must go where the evidence leads. An alternative reply in line with the second variant of the previous paragraph denies the charge of inexplicability by supposing that emergent features are the product of micro-structural dispositions that, unlike those which are more or less continuously manifested, have structural triggering conditions.
A Laplacian observer of the unfolding universe prior to the initial onset of such emergent features would have no inkling of there being such latent dispositions towards collective emergent effects. Two other reasons for resisting attempts to interpret possible discontinuous microphysical behavior in terms of micro-physical powers alone are epistemological.
One might contend that we should seek to provide as unified an explanation as possible of such phenomena, and that an explanation in micro-physical terms alone would be highly complex and disunified compared to one that posits a family of emergent macroscopic determinables fitted to structures of organized complexity.
Second, we can describe certain possible situations involving causal indeterminism that would be readily understandable in strong emergentist terms, whereas the only microphysical explanation possible would require an objectionable action at a temporal distance.
Finally, possible responses to the final, evidential challenge to strong emergence are best considered in section 5 , where a range of candidate emergent phenomena are introduced.
Notwithstanding the replies just above to the collapse challenge, a recent trend in theorizing about strong emergence has been to embrace collapse, arguing that emergence is better understood as the introduction of novel powers had by components when embedded in configured wholes.
This section introduces four ways this account has been developed. In a series of articles culminating in a book, Carl Gillett advances a distinctive account of strong emergence rooted in a hierarchy-of-mechanism picture of complex systems that, he maintains, is strongly supported by a range of sciences. Gillett invokes considerable conceptual machinery in developing his view; making substitutions in linked definitions, we arrive at the following compact statement:. It is tempting to think of this last as also ascribing a novel albeit non-productive power to the emergent property, although Gillett does not describe it in these terms.
As regards the general charge that strong emergence is inexplicable, Gillett maintains that this account provides an intelligible, scientifically informed basis for making sense of strong emergence. As regards the charge of there being no evidence of strong emergence, Gillett suggests that while its reality has not been established empirically, it is seriously proposed by a number of contemporary theorists of complex systems see section 5.
He discusses the way that the bent geometry of a water molecule determines its dipole moment, which latter feature confers a range of causal powers on the molecule, such as its disposition to align in an electric field and its being liquid at room temperature — As he puts it:. Properties such as molecular geometry are causally fundamental […] because their bearers have certain causal powers in virtue of meeting their defining specifications, but not in virtue of the realizer properties in virtue of which they meet those specifications on a given occasion.
Yates contends that these examples demonstrate the reality of his distinctive variety of strong emergence. A skeptic might press that the effects Yates cites as pointing to a distinctive kind of higher-level causal power are themselves all higher-level. It might well be the case that to explain the token effects under their macroscopic description requires equally macroscopic appeal to molecular geometry where a given geometric shape is multiple realizable by distinct spatial arrays of atoms.
The account differs, however, in maintaining that in the evolving dynamic that follows the appearance of such new powers, there come to be emergent macro-states that together with the transformed micro-entities determine subsequent micro- and macro-states.
Sydney Shoemaker , , while agreeing with Gillett and Ganeri that emergence occurs within special kinds of organized objects or systems and features novel component powers, dispenses with any downward determination relation, causal or otherwise.
But these powers are novel in a qualified way:. The component entities have powers that, collectively, determine the instantiation of the emergent property when they are combined in an emergence-engendering way. But these being cases of emergence, these cannot all be powers that manifest themselves when the components are not combined in emergence-engendering ways.
Shoemaker With the advent of new powers, there are new laws describing their evolution. The dynamic itself is constantly evolving, as elements are transformed through interactions with other elements. Santos suggests that such a view of things is indicated by modern cellular and developmental biology, but the theoretical descriptions he cites e.
The issue of whether enduring structured entities are essential or inessential to the broad frameworks embraced by the special sciences is a large issue that cannot be discussed here. As an intuitive though perhaps not realistic example, he notes that people undergo significant temporary psychological change when they are caught up in the interactions constituting a mob. Here there is fundamental change apart from any triggering interactions, and not merely a change within individuals but change of individuals from one kind to others.
When fusion occurs, basal entities or certain of their properties are lost when they fuse with others in producing a unified whole 74—5. Transformational accounts clearly stretch the classical concept which informs the taxonomy of the present article. The common thread is simply that of fundamental but lawlike change in the observable patterns in physical reality through time.
For purposes of assessing how competing accounts fare in characterizing the range of empirical phenomena uncovered in the sciences, it may be necessary for greater terminological regimentation to emerge.
This view is common enough among emergentists that some influential theorists took it to be a defining element of the doctrine. But one can argue that strong emergentism, at least with respect to some or all mental states, in fact requires a form of substance dualism.
On a biological view of emergent thinkers, the micro-physical boundaries of such thinkers may inevitably be vague, for empirical reasons. But it is perhaps doubtful that fundamental causal laws associated with strongly emergent properties would reference vague conditions.
The sole apparent alternative is that the properties are instantiated in a distinct, non-vague object instead, as a non-physical mind would be. Certain phenomena and theoretical considerations motivating some contemporary theorists to endorse a strong emergentist construal of those phenomena. It bears emphasis that strong emergentists typically also suppose that some interesting organized behavior is more plausibly understood either reductively or as weakly emergent: their strong emergentism is piecemeal.
This final section summarizes those phenomena and considers in general terms the different ways strong and weak emergentists might go about treating them. The conscious mind in its different aspects has long seemed to many to resist plausible ontological characterization in any physical terms, whether reductive or non-reductive i.
For a fairly comprehensive overview, see Chalmers Consider, for a start, our apparently direct awareness of our own conscious experiential states. Conscious cognitive states such as beliefs and desires have complicating aspects that cannot be explored here.
But see section 5. Such strong fallibilism about the contents of consciousness seems implausible, as is shown by the fact that philosophers such as Descartes who entertain radical skeptical doubts about much of human knowledge do not typically extend it to our grasp of our current conscious experience.
It seems not, but it is hard to account for this datum in physicalist terms. Also puzzling for physicalism is the unity of conscious experience: the fact that our experiences engaging distinct sensory modalities and our conscious thoughts, moods, and feelings come together as aspects of one overall conscious state of a single conscious subject.
On a plausible physicalist account, each of these aspects will be realized in distinct, physically-separated neural networks, but as yet there is no worked-out physicalist strategy for capturing the unity of these aspects in experience. In recent decades, highly general functional characterizations of conscious awareness have been proposed, notably: higher-order theories, on which a state is conscious just in case it stands in the right kind of relationship to a higher-order state that represents it Carruthers ; Rosenthal ; entry on higher-order theories of consciousness ; global workspace theories, on which a state is conscious just in case its content is globally accessible to multiple cognitive subsystems Baars , Dehaene et al.
See Bayne and Schechter for philosophical exploration of clinical accounts regarding the reports of split-brain patients. This suggests a physicalist strategy of using these unusual phenomena as a tool for chipping away at the ostensible phenomenological basis for rejecting the possibility of an eventual physicalist account of consciousness.
See entry on the unity of consciousness , Sect. An alternative, perhaps complementary physicalist strategy is to argue that certain seeming aspects of consciousness are simply illusions which can be explained in terms of inevitable organizational tradeoffs in the construction of finite minds see Pereboom and Chalmers Rather, such experiential qualities seem to be distinctive in kind, engendering a mismatch with the physical-structural or functional kinds posited by physical theories, and to have a degree of simplicity that is incongruent with the massive physical complexity of the associated physical processes.
For two much-discussed arguments from these apparent characteristics of conscious experience to at least a modest form of physical-mental dualism, see Jackson and entry on qualia and the knowledge argument ; and Chalmers and entry on zombies. This limited anti-physicalism most lends itself to—although it does not entail—the epiphenomenalist version of strong emergence discussed in 4.
However, one may question the independence of phenomenal and intentional properties see, e. If some such connection thesis is correct, then not only experiences, but other cognitive states such as belief and desire may resist purely physical characterization see entry on phenomenal intentionality. Human and other animals are not only experiencers and knowers but also doers. The nature of non-human animal choice or volition and their concomitant experience of action is here set aside, as it is difficult to conjecture concerning it with any confidence on present knowledge.
At least sometimes, we seem to ourselves not to be merely loci in which a host of psychological and merely physical influences converge and resolve themselves in behavior, but rather to exercise a power to decide which among the options we are considering we shall take, thereby determining whether and how these influences will be acted upon. Such agential experience, if veridical, might indicate that the ability to freely choose is strongly emergent.
Coupled with the plausible position that mental states of whatever variety depend on lower-level physical states, such a result might be seen as providing support for taking free will to be a strongly emergent power. Agential experience is defeasible, and cognitive and social psychology and more recently neuroscience have been probing the determinants of choice and its relationship to conscious awareness.
One particular form of study has been taken by many to undermine the veridicality of the experience of conscious control over arbitrary choice. Some note that the ability of subjects to precisely time their own conscious events of any kind including simple perceptual cues have been shown to be not fully reliable: their estimates can be manipulated by conscious primes before and after the target event.
They also come in degrees of intensity, such that the onset of an event that might quickly intensify or otherwise evolve might be more difficult to determine than the event itself.
Others observe that the studies do not even purport to identify a determining physical antecedent to conscious choice. Finally, other recent studies beginning with Schurger et al. Examples of emergent properties include cities, the brain, ant colonies and complex chemical systems. A single ant is a rather limited organism, with little ability to reason or accomplish complex tasks.
As a whole, however, an ant colony accomplishes astounding tasks, from building hills and dams to finding and moving huge amounts of food. In this context, emergent properties are the changes that occur in ant behavior when individual ants work together. Alone, an ant behaves erratically and almost at random. But millions of random actions by thousands and thousands of ants can serve to identify necessary tasks and organize other ants to complete them.
An ant that finds food, for example, secretes a small amount of a hormonal substance that attracts other ants which, in turn, also secrete that same substance when they reach the same food source. Thus, thousands of wandering ants become the organized in straight lines leading to the nearest picnic. The organization of ants, only possible when the system works as a whole and individual actions reinforce each other, is an emergent property. Human consciousness is often called an emergent property of the human brain.
Like the ants that make up a colony, no single neuron holds complex information like self-awareness, hope or pride. Nonetheless, the sum of all neurons in the nervous system generate complex human emotions like fear and joy, none of which can be attributed to a single neuron. Although the human brain is not yet understood enough to identify the mechanism by which emergence functions, most neurobiologists agree that complex interconnections among the parts give rise to qualities that belong only to the whole.
Emergent properties are cornerstones for comprehending human - ecosystem interactions in ways that provide insights for sustainable development. This chapter will begin by explaining the concept of emergent properties. It will then describe three significant examples of emergent properties in detail:. Biological systems have a hierarchy of organizational levels that extends from molecules and cells to individual organisms, populations and ecosystems.
Every individual plant and animal is a collection of cells; every population is a collection of individual organisms of the same species; and every ecosystem consists of populations of different species. The most important levels of biological organization for human ecology are populations and ecosystems. Each level of biological organization from molecules to ecosystems has characteristic behaviours which emerge at that level.
These distinct behaviours, called emergent properties , function synergistically at each level of organization to give that level a life of its own which is greater than the sum of its parts. This happens because all the parts fit together in ways that allow the system as a whole to function in a manner that promotes its survival. Because the parts are interconnected, the behaviour of every part is shaped by feedback loops through the rest of the system. A mixture of positive and negative feedback promotes growth and change in the system as a whole.
Emergent properties are easiest to perceive in individual organisms. In simple organisms such as jellyfish, we can identify basic emergent properties such as growth, development of different tissues and organs, homeostasis, reproduction and death. The richness of expression of emergent properties increases with the complexity of the organism. Visual images are not a property of the component cells in organisms; the experience of visual images emerges at the level of an entire organism.
Emotions such as fear, anger, anxiety, hate, happiness and love are also emergent properties. The sigmoid curve for population growth, population regulation, genetic evolution and social organization are examples of emergent properties at the population level of organization. They are not properties of the individuals in a population.
They emerge as special properties of populations because every individual in a population is affected by what happens in the population as a whole. Taking population regulation as an example, individual plants and animals have the potential to live a long life, producing a large number of offspring. However, the actual survival and reproduction of each individual depends on how many other individuals are in the population and how this number compares to carrying capacity.
If the total population overshoots carrying capacity, some individuals in the population are compelled to die from lack of food. The result is population regulation within the limits of carrying capacity - an emergent property of populations.
What about emergent properties of ecosystems? The component parts of ecosystems are all limited by their connections to other parts of the ecosystem. More emergent properties of ecosystems will be described in later chapters. Components at one level of organization interact primarily with other components at the same level. They do so by responding to information that emerges from those components.
Protein molecules in the cell interact with other molecules in ways that respond to the structure and behaviour of the molecules, not the atoms of which they are composed.
Proteins have an intricate three-dimensional structure that emerges at the level of the molecule and provides the basis for interaction with other molecules. When cats hunt mice, they do not process information on all the parts of a mouse in order to detect it.
Instead, they respond to key features that emerge at the level of the whole mouse: body size; large ears; long thin tail, etc. They do not process information about the cellular structure of these features.
Mice respond to cats in a similar way. One emergent property of ecosystems and social systems is counterintuitive behaviour. They sometimes do the opposite of what we expect. The purpose of public housing was to reduce poverty by providing decent housing to low-income people at a price they could afford.
However, cheap housing encouraged unskilled people to move from rural areas to cities even when there were no jobs. The large number of unemployed people turned public housing into ghettos of poverty. The effect of public housing was the opposite of its intended purpose because what happened depended not only on the housing but also on feedback loops through other parts of the social system.
The story of forest fire protection provides an example of counterintuitive behaviour in ecosystems. Forest managers tried to reduce fire damage by putting out fires. The result was even more fire damage. Details of this story are in Chapter 6.
Ecosystems and social systems are sometimes counterintuitive because they are not easily understood by people whose main existence is at a different level of organization - the level of an individual inside the ecosystem and social system. This difference is one important reason why people find it difficult to predict the ultimate consequences of their actions on ecosystems. Emergent properties of our own individual level of organization - our bodies, our consciousness and our direct interactions with people and other parts of the ecosystem - are obvious to us, but emergent properties at higher levels of organization are not so obvious.
From its travels around the body, the red blood cell is quite familiar with the different parts of the body - the brain, the eye and so on - but it is very difficult for it to comprehend vision, thoughts, emotions and activities that come from the body as a whole.
People, as a small part of ecosystems and social systems, have the same difficulty comprehending ecosystems and social systems. Emergent properties of the human social system are important for human ecology because they shape the ways in which people interact with ecosystems. One emergent property is distortion of information when errors accumulate as information passes through a social network. That person whispers the message to a second person, and the message is whispered from one person to another.
After everyone has been told the message, the first person and last person tell everyone the message as they understood it. Another emergent property is denial , refusal to recognize or accept the truth when it conflicts with existing beliefs.
Selective filtering of information helps to protect existing belief systems of individuals and shared belief systems of society. For example, European nations with global empires were blind to the oppression and exploitation of colonialism. In a similar fashion, it is not unusual for governments and powerful people who profit from unsustainable logging of tropical forests to believe that small-scale peasant farmers are primarily to blame for deforestation, even though local farmers generally use forest resources in an ecologically sound fashion.
During the s and s, some ecologists tried to warn the public about the impending dangers of the human population explosion and environmental degradation. Most people, including government officials and business leaders with considerable power, would not believe it, even though the facts were clear.
Most people considered warnings about impending environmental problems to be extremist. It took several decades and numerous environmental disasters for people to start accepting that the problems were real. This denial had a major effect on social system - ecosystem interaction because so much time was lost before people started to take the environment seriously. This costly form of denial continues as some people, including influential politicians, persist in doubting the reality of global warming despite overwhelming evidence.
Bureaucracies provide examples of emergent properties in human social systems. One emergent property is that bureaucracies are not very effective at dealing with unusual situations. This is because bureaucracies use standard operating procedures to operate efficiently on a large scale. Bureaucracies may be effective for routine matters, but they may not do so well with unusual situations because their procedures are not designed for those situations.
Another emergent property of bureaucracies is that they often do things that are contrary to their mission. These are characteristics of a bureaucracy as a whole. They do not derive from the characteristics of individuals in the bureaucracy, who are usually conscientious workers. Their jobs may compel them to do things that make no sense to them personally.
Why do all the different parts of an ecosystem fit together so well? What is responsible for organizing all the parts, their functional connections and resulting feedback loops, in a way that allows everything to function together?
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