[Note: The following essay is the Introduction to a new book by Manuel DeLanda, easily the most important philosopher of the present day, concerning topics and concepts of particular relevance, I believe, for contemporary and future architects. It is considerably longer than my usual posts, but the clarity of DeLanda's writing makes it a compelling read. It is published here under rights of Fair Use in international copyrights law, meaning for educational and research purposes only. The book, entitled Philosophy and Simulation: The Emergence of Synthetic Reason, will be published by Continuum, London, in January 2011. LW]
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(above) Manuel DeLanda.
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EMERGENCE IN HISTORY
The origin of the modern concept of emergence can be traced to the middle of the nineteenth century when realist philosophers first began pondering the deep dissimilarities between causality in the fields of physics and chemistry. The classical example of causality in physics is a collision between two molecules or other rigid objects. Even in the case of several colliding molecules the overall effect is a simple addition. If, for example, one molecule is hit by a second one in one direction and by a third one in a different direction the composite effect will be the same as the sum of the two separate effects: the first molecule will end up in the same final position if the other two hit it simultaneously or if one collision happens before the other. In short, in these causal interactions there are no surprises, nothing is produced over and above what is already there. But when two molecules interact chemically an entirely new entity may emerge, as when hydrogen and oxygen interact to form water. Water has properties that are not possessed by its component parts: oxygen and hydrogen are gases at room temperature while water is liquid. And water has capacities distinct from those of its parts: adding oxygen or hydrogen to a fire fuels it while adding water extinguishes it.
The fact that novel properties and capacities emerge from a causal interaction was believed to have important philosophical implications for the nature of scientific explanation. In particular, the absence of novelty in physical interactions meant that explaining their effects could be reduced to deduction from general principles or laws. Because deductive logic simply transfers truth from general sentences to particular ones without adding anything new it seemed like an ideal way of modeling the explanation of situations like those involving rigid collisions. But the synthesis of water does produce something new, not new in the absolute sense of something that has never existed before but only in the relative sense that something emerges that was not in the interacting entities acting as causes. This led some philosophers to the erroneous conclusion that emergent effects could not be explained, or what amounts to the same thing, that an effect is emergent only for as long as a law from which it can be deduced has not yet been found. This line of thought went on to become a full fledged philosophy in the early twentieth century, a philosophy based on the idea that emergence was intrinsically unexplainable. This first wave of “emergentist” philosophers were not mystical thinkers but quite the opposite: they wanted to use the concept of emergence to eliminate from biology mystifying entities like a “life force” or the “élan vital”. But their position towards explanation gave their views an inevitable mystical tone: emergent properties, they said, must be accepted with an attitude of intellectual resignation, that is, they must be treated as brute facts towards which the only honest stance is one of natural piety.
Expressions like these were bound to make the concept of emergence suspect to future generations of philosophers. It was only the passage of time and the fact that mathematical laws like those of classical physics were not found in chemistry or biology – or for that matter, in the more historical fields of physics, like geology or climatology – that would rescue the concept from intellectual oblivion. Without simple laws acting as self-evident truths (axioms) from which all causal effects could be deduced as theorems the axiomatic dream eventually withered away. Today a scientific explanation is identified not with some logical operation but with the more creative endeavor of elucidating the mechanisms that produce a given effect. The early emergentists dismissed this idea because they could not imagine anything more complex than a linear clockwork mechanism. But there are many other physical mechanisms that are nonlinear. Even in the realm of human technology we have a plurality of exemplars to guide our imagination: steam engines, thermostats, transistors. And outside technology the diversity is even greater as illustrated by all the different mechanisms that have been discovered in chemistry and biology. Armed with a richer concept of mechanism the emergent properties of a whole can now be explained as an effect of the causal interactions between its component parts. A large portion of this book will be dedicated to describe the wide variety of mechanisms of emergence that have been elucidated in the decades since the original emergentists first wrote.
Thus, what is different today from the early twentieth century views is the epistemological status of emergence: it does not have to be accepted as a brute fact but can be explained without fearing that it will be explained away. What has remained the same is the ontological status of emergence: it still refers to something that is objectively irreducible. But what kinds of entities display this ontological irreducibility? The original examples of irreducible wholes were entities like “Life”, “Mind”, or even “Deity”. But these entities cannot be considered legitimate inhabitants of objective reality because they are nothing but reified generalities. And even if one does not have a problem with an ontological commitment to entities like these it is hard to see how we could specify mechanisms of emergence for life or mind in general, as opposed to accounting for the emergent properties and capacities of concrete wholes like a metabolic circuit or an assembly of neurons. The only problem with focusing on concrete wholes is that this would seem to make philosophers redundant since they do not play any role in the elucidation of the series of events that produce emergent effects. This fear of redundancy may explain the attachment of philosophers to vague entities as a way of carving out a niche for themselves in this enterprise. But realist philosophers need not fear irrelevance because they have plenty of work creating an ontology free of reified generalities within which the concept of emergence can be correctly deployed.
What kinds of concrete emergent wholes can we legitimately believe in? Wholes the identity of which is determined historically by the processes that initiated and sustain the interactions between their parts. The historically contingent identity of these wholes is defined by their emergent properties, capacities, and tendencies. Let’s illustrate the distinction between properties and capacities with a simple example. A kitchen knife may be either sharp or not, sharpness being an actual property of the knife. We can identify this property with the shape of the cross section of the knife’s blade: if this cross section has a triangular shape then the knife is sharp else it is blunt. This shape is emergent because the metallic atoms making up the knife must be arranged in a very particular way for it to be triangular. There is, on the other hand, the capacity of the knife to cut things. This is a very different thing because unlike the property of sharpness which is always actual the capacity to cut may never be actual if the knife is never used. In other words, a capacity may remain only potential if it is never actually exercised. This already points to a very different ontological status between properties and capacities. In addition, when the capacity does become actual it is not as a state, like the state of being sharp, but as an event, an event that is always double: to cut-to be cut. The reason for this is that the knife’s capacity to affect is contingent on the existence of other things, cuttable things, that have the capacity to be affected by it. Thus, while properties can be specified without reference to anything else capacities to affect must always be thought in relation to capacities to be affected. Finally, the ontological relation between properties and capacities displays a complex symmetry. On one hand, capacities depend on properties: a knife must be sharp to be able to cut. On the other, the properties of a whole emerge from interactions between its component parts, interactions in which the parts must exercise their own capacities: without metallic atoms exercising their capacity to bond with one another the knife’s sharpness would not exist.
A similar distinction can be made between emergent properties and tendencies. To stick to the same example: a knife has the property of solidity, a property that is stable within a wide range of temperatures. Nevertheless, there are always environments that exceed that range, environments in which the temperature becomes so intense that the knife is forced to manifest the tendency to liquify. At even greater intensities the molten metal may gasify. These tendencies are as emergent as the shape of a knife’s blade: a single metallic atom cannot be said to be solid, liquid, or gas; we need a large enough population of interacting atoms for the tendency to be in any of these states to emerge. Tendencies are similar to capacities in their ontological status, that is, they need not be actual to be real, and when they do become actual is as events: to melt or to solidify. The main difference between tendencies and capacities is that while the former are typically finite the latter need not be. We can enumerate, for example, the possible states in which a material entity will tend to be (solid, liquid, gas, plasma) or the possible ways in which it may tend to flow (uniformly, periodically, turbulently). But capacities to affect need not be finite because they depend on the capacities to be affected of innumerable other entities: a knife has the capacity to cut when it interacts with something that has the capacity to be cut; but it also has the capacity to kill if it interacts with large organisms with differentiated organs, that is, with entities that have the capacity to be killed.
Since neither tendencies nor capacities must be actual to be real it would be tempting to give them the status of possibilities. But the concept of a possible event is philosophically suspect because it is almost indistinguishable from that of a real event, the only difference being the former’s lack of reality. Rather, what is needed is a way of specifying the structure of the space of possibilities that is defined by an entity’s tendencies and capacities. A philosopher’s ontological commitment should be to the objective existence of this structure and not to the possibilities themselves since the latter exist only when entertained by a mind. Some possibility spaces are continuous having a well defined spatial structure that can be investigated mathematically, while others are discrete, possessing no inherent spatial order but being nevertheless capable of being studied through the imposition of a certain arrangement. The space of possible regimes of flow (uniform, periodic, turbulent) is an example of a continuous possibility space in which the only discontinuities are the critical points separating the different tendencies. The space of possible genes, on the other hand, is an example of a discrete space that must be studied by imposing an order on it, such as an arrangement in which every gene has as neighbors other genes differing from it by a single mutation. As we will see in the different chapters of this book the structure of possibility spaces plays as great a role in the explanation of emergence as do mechanisms.
The chapters are deliberately arranged in a way that departs from the ideas of the original emergentists. These philosophers believed that entities like “Space-Time”, “Life”, “Mind”, and “Deity” (not “god” but the sense of the sacred that emerges in some minds) formed a pyramid of progressively ascending grades. Although the levels of this pyramid were not supposed to imply any teleology it is hard not to view each level as leading to the next following a necessary sequence. To eliminate this possible interpretation an entirely different image is used here, that of a contingent accumulation of layers or strata that may differ in complexity but that coexist and interact with each other in no particular order: a biological entity may interact with a subatomic one, as when neurons manipulate concentrations of metallic ions, or a psychological entity interact with a chemical one, as when subjective experience is modified by a drug. The book begins with purely physical entities, thunderstorms, that are already complex enough to avoid the idea that their behavior can be deduced from a general law. It then moves on to explore the prebiotic soup, bacterial ecosystems, insect intelligence, mammalian memory, primate social strategies, and the emergence of trade, language, and institutional organizations in human communities. Each of these layers will be discussed in terms of the mechanisms of emergence involved, drawing ideas and insights from the relevant fields of science, as well as in terms of the structure of their possibility spaces, using the results of both mathematical analysis and the outcomes of computer simulations.
Simulations are partly responsible for the restoration of the legitimacy of the concept of emergence because they can stage interactions between virtual entities from which properties, tendencies, and capacities actually emerge. Since this emergence is reproducible in many computers it can be probed and studied by different scientists as if it were a laboratory phenomenon. In other words, simulations can play the role of laboratory experiments in the study of emergence complementing the role of mathematics in deciphering the structure of possibility spaces. And philosophy can be the mechanism through which these insights can be synthesized into an emergent materialist world view that finally does justice to the creative powers of matter and energy.
MANUEL DELANDA
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