Encyclopedia of Nonlinear Science
Like many commonly used words, the term emergence has several meanings. In its weakest sense, a metaphor is provided by Michelangelo Buonarroti’s famous sculptures entitled The Prisoners, which show human figures struggling to free themselves from their lithic confines, suggesting the artist’s view of the creative process.
In simplest terms, there is little mystery here; the sculptor merely removes the unnecessary marble to expose the finished work, as Michelangelo himself is said to have pointed out. Thus, his prisoners are emerging only in an elementary sense which philosopher Robert Van Gulick calls “specific value emergence” and defines as follows (Van Gulick, 2001):
Moving beyond this limited sense, Van Gulick defines various degrees of “modest emergence” in these terms.
Modest emergence thus arises in a spectrum of different ways depending upon the degree of difference between a phenomenon and the base out of which it emerges, with the coherent structures of nonlinear science providing many examples (Scott, 2003).
Among the more modest types of emergence, one would include solitons of the Korteweg-deVries (KdV) equation, which emerge out of a nonlinear partial differential equation (PDE) in response to certain initial conditions. Although KdV solitons are independent dynamic entities, their speeds and shapes are determined via the inverse scattering transform (IST) method from the initial conditions applied to the system. Somewhat less modest would be the various solitary wave solutions of Hamiltonian (energy conserving) systems for which IST formulations are not currently known and may not exist, precluding the prediction of solitary wave speeds from initial conditions.
Further decreasing modesty (increasing robustness) of emergence leads to the nerve impulse, which has several model PDEs (Hodgkin-Huxley, FitzHugh-Nagumo, etc.) in addition to those many physiological manifestations (the action potentials of the brain) which compose our mental activity (Scott, 2002). While propagating on a uniform system with constant speed and shape, a nerve impulse differs fundamentally from solitary waves of Hamiltonian systems for the following reason: a nerve impulse (like the flame of a candle) does not conserve energy. The nonlinear dynamics of a nerve impulse involves a balance between the release and dissipation of energy, so the process is open and thus does not have a Hamiltonian formulation. This, in turn, implies that the dynamic behavior of a nerve impulse changes greatly upon reversal of the direction of time, whereas the qualitative behavior of a Hamiltonian system is insensitive to time reversal.
Under this distinction, we can gauge the relative modesty of several other types of emergence that arise in the realms of nonlinear science. Vortex solutions of viscosity-free fluids (superfluids, for example) would be more modestly emergent than those of (more or less) viscous fluids, in which dissipative processes cause the dynamics to (more or less) rapidly forget the information received from the initial conditions. As residents of Tornado Alley in the U.S. midlands know well, tornados are famously ill-behaved, detached from their initial conditions and moving quite wildly in response to local variations of pressure, humidity, temperature, and so on.
A deeper meaning of Michelangelo’s metaphor suggests the emergence of living organisms from the oily brine of the Hadean oceans some three thousand million years ago. Life is even less modestly (more robustly) emergent, with the “arrow of time” clearly constraining us all and playing a key role in the unpredictable drama of biological evolution (Gould, 1989). In other words, the emergence of life is far more intricate than the emergence of John Scott Russell’s soliton from the prow of his test vessel on the Union Canal.
Yet more robust (less immodest) than the emergence of life is the phenomenon of human consciousness, which philosophers have struggled for centuries to understand and many find qualitatively different from its material substrate. To include the qualitative aspects of emergence at this far end of the scale, Van Gulick introduces the following definition.
Whether human consciousness offers an example of radical emergence is currently controversial among cognitive scientists, neuroscientists, psychologists, cultural anthropologists, philosophers, and others interested in the nature of mind. On the one hand, reductive materialists assert that all of reality must “in principle” reduce to a physical basis (Kim, 1999), whereas substance dualists claim that the human mind differs ontologically (in its nature) from physical reality (Chalmers, 1996). Situated between these two positions, property dualists suggest that the human mind may radically emerge from intricate interactions among the various nonlinear dynamic levels of body, brain, and culture (Scott, 1995; Van Gulick, 2001).
ALWYN SCOTT
See also Biological evolution; Game of life; Morphogenesis, biological
Further Reading
Chalmers, D. 1996. The Conscious Mind: In Search of a Fundamental Theory, Oxford and New York: Oxford University Press
Gould, S.J. 1989. Wonderful Life: The Burgess Shale and the Nature of History, New York and London: Norton
Kim, J. 1999. Mind in a Physical World, Cambridge, MA: MIT Press
Scott, A.C. 1995. Stairway to the Mind: The Controversial New Science of Consciousness, Berlin and New York: Springer
Scott, A.C. 2002. Neuroscience: A Mathematical Primer, Berlin and New York: Springer
Scott, A.C. 2003. Nonlinear Science: Emergence and Dynamics of Coherent Structures, 2nd edition, Oxford and New York: Oxford University Press
Van Gulick, R. 2001. Reduction, emergence and other recent options on the mind/body problem. Journal of Consciousness Studies, 8(9–10): 1–34
This is the complete article, containing 1,057 words
(approx. 4 pages at 300 words per page).
View More Summaries on Emergence
