Reductionism

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Reductionism can either mean (a) an approach to understanding the nature of complex things by reducing them to the interactions of their parts, or to simpler or more fundamental things or (b) a philosophical position that a complex system is nothing but the sum of its parts, and that an account of it can be reduced to accounts of individual constituents. This can be said of objects, phenomena, explanations, theories, and meanings.

Reductionism is strongly related to a certain perspective on causality. In a reductionist framework, phenomena that can be explained completely in terms of other, more fundamental phenomena, are called epiphenomena. Often there is an implication that the epiphenomenon exerts no causal agency on the fundamental phenomena that explain it.

History

The idea of reductionism was introduced by Descartes in Part V of his Discourses (1637). Descartes argued the world was like a machine, its pieces like clockwork mechanisms, and that the machine could be understood by taking its pieces apart, studying them, and then putting them back together to see the larger picture.

Descartes was a full mechanist, but only because he did not accept the conservation of direction of motions of small things in a machine, including an organic machine. Newton's theory required such conservation for inorganic things at least. When such conservation was accepted for organisms as well as inorganic objects by the middle of the 20th century, no organic mechanism could easily, if at all, be a Cartesian mechanism.

Reductionism & Science

Reductionist thinking and methods are the basis for many of the well-developed areas of modern science, including much of physics, chemistry and cell biology. Classical mechanics in particular is seen as a reductionist framework, and statistical mechanics can be viewed as a reconciliation of macroscopic thermodynamic laws with the reductionist approach of explaining macroscopic properties in terms of microscopic components.

The term Scientific reductionism has been used to describe the idea that all phenomena can be reduced by scientific explanations..

In science, reductionism can be understood to imply that certain fields of study are based on areas that study smaller spatial scales or organizational units. While it is commonly accepted that most aspects of chemistry are based on physics, and similarly many aspects of microbiology are based on chemistry, such statements become controversial when one considers larger-scale fields. For example, claims that sociology is based on psychology, or that economics is based on sociology and psychology would be met with reservations. These claims are difficult to substantiate even though there are clear connections between these fields (for instance, most would agree that psychology can impact and inform economics.) The limit of reductionism's usefulness stems from emergent properties of complex systems which are more common at certain levels of organization. For example, certain aspects of evolutionary psychology and sociobiology are rejected by some who claim that complex systems are inherently irreducible and that a holistic approach is needed to understand them.

Some strong reductionists believe that the behavioral sciences should become "genuine" scientific disciplines by being based on genetic biology, and on the systematic study of culture (cf. Dawkins's concept of memes). In his book The Blind Watchmaker, Richard Dawkins introduced the term "hierarchical reductionism" (p. 13) to describe the view that complex systems can be described with a hierarchy of organizations, each of which can only be described in terms of objects one level down in the hierarchy. He provides the example of a computer, which under hierarchical reductionism can be explained well in terms of the operation of hard drives, processors, and memory, but not on the level of AND or NOR gates, or on the even lower level of electrons in a semiconductor medium.

Others, including the ecologist Robert Ulanowicz, argues that inappropriate use of reductionism limits our understanding of complex systems. He argues that science must develop techniques to study ways in which larger scales of organization influence smaller ones, and also ways in which feedback loops create structure at a given level, independently of details at a lower level of organization. He advocates (and uses) information theory as a framework to study propensities in natural systems. Ulanowicz attributes these criticisms of reductionism to the philosopher Karl Popper and biologist Robert Rosen.

Reductionism in Mathematics

In mathematics, reductionism can be interpreted as the philosophy that all mathematics can (or ought to be) be built off a common foundation, which is usually axiomatic set theory. Ernst Zermelo was one of the major advocates of such a view, and he was also responsible for the development of much of axiomatic set theory. It has been argued that the generally accepted method of justifying mathematical axioms by their usefulness in common practice can potentially undermine Zermelo's reductionist program.

As an alternative to set theory, others have argued for category theory as a foundation for certain aspects of mathematics.

Ontological reductionism

Ontological reductionism is a philosophy or belief that everything that exists is made from a small number of basic substances that behave in regular ways (compare to monism). Ontological reductionism denies the idea of ontological emergence, and claims that emergence is an epistemological phenomenon that only exists through analysis or description of a system, and does not exist on a fundamental level.

Ontological reductionism takes two different forms: Token ontological reductionism is the idea that every item that exists is a sum item. For perceivable items, it says that every perceivable item is a sum of items at a smaller level of complexity. Type ontological reductionism is the idea that every type of item is a sum (of typically less complex) type(s) of item(s). For perceivable types of item, it says that every perceivable type of item is a sum of types of items at a lower level of complexity. Token ontological reduction of biological things to chemical things is generally accepted. Type ontological reduction of biological things to chemical things is often rejected.

Ontological reductionism has been criticized as an improper argument against vitalism.

Reductionism in Linguistics

Linguistic reductionism is the idea that everything can be described in a language with a limited number of core concepts, and combinations of those concepts. (See Basic English and the constructed language Toki Pona).

Limits of Reductionism

A contrast to the reductionist approach is holism or emergentism. Holism recognizes the idea that things can have properties as a whole that are not explainable from the sum of their parts (emergent properties). The principle of holism was concisely summarized by Aristotle in the Metaphysics: "The whole is more than the sum of its parts".

The term Greedy reductionism, coined by Daniel Dennett, is used to criticize inappropriate use of reductionism. Other authors use different language when describing the same thing.

In Philosophy

The concept of downward causation poses an alternative to reductionism within philosophy. This view is developed and explored by Peter Bøgh Andersen, Claus Emmeche, Niels Ole Finnemann, and Peder Voetmann Christiansen, among others. These philosophers explore ways in which one can talk about phenomena at a larger-scale level of organization exerting causal influence on a smaller-scale level, and find that some, but not all proposed types of downward causation are compatible with science. In particular, they find that constraint is one way in which downward causation can operate. The notion of causality as constraint has also been explored as a way to shed light on scientific concepts such as self-organization, natural selection, adaptation, and control.

In Science

Phenomena such as emergence and work within the field of complex systems theory pose limits to reductionism. Stuart Kauffman is one of the advocates of this viewpoint. Emergence is strongly related to nonlinearity. The limits of the application of reductionism become especially evident at levels of organization with higher amounts of complexity, including culture, neural networks, ecosystems, and other systems formed from assemblies of large numbers of interacting components.

Sven Erik Jorgensen, an ecologist, lays out both theoretical and practical arguments for a holistic approach in certain areas of science, especially ecology. He argues that many systems are so complex that it will not ever be possible to describe all their details. Drawing an analogy to the Heisenberg uncertainty principle in physics, he argues that many interesting and relevant ecological phenomena cannot be replicated in laboratory conditions, and thus cannot be measured or observed without influencing and changing the system in some way. He also points to the importance of interconnectedness in biological systems. His viewpoint is that science can only progress by outlining what questions are unanswerable and by using models that do not attempt to explain everything in terms of smaller hierarchical levels of organization, but instead model them on the scale of the system itself, taking into account some (but not all) factors from levels both higher and lower in the hierarchy.

Disciplines such as cybernetics and systems theory strongly embrace a non-reductionist view of science, sometimes going as far as explaining phenomena at a given level of hierarchy in terms of phenomena at a higher level, in a sense, the opposite of a reductionist approach..

In decision Theory

In decision theory, a nonlinear utility function for a quantity such as money can create a situation in which all relevant decisions to be made in a given time period must to be considered simultaneously in order to maximize utility, if all relevant decisions act on utility only through this quantity. In such a situation, the optimal choice for a given decision depends on the possible outcomes of all other decisions, including those which may have no causal relationship to the decision at hand. Breaking such a problem apart into individual decisions and optimizing each smaller decision can lead to drastically sub-optimal decisions. Such nonlinear utility functions for money are used in economics and are necessary in order to satisfy reasonable assumptions about rational behavior. Such decision making situations are the norm, rather than the exception, in many business settings.

In Religion

Some religious belief or doctrine assigns supernatural original causes to phenomena. In this context, even if a given system appears to operate by causes and effects that can be explained within a strict reductionist framework, belief or doctrine might hold that its true genesis and placement within larger (and typically unknown) systems is bound up with an intelligence or consciousness that is beyond normal or uninvited human perception. Some such beliefs constitute a form of teleology, a perspective which is generally in conflict with reductionism.

References

Dawkins, R. (1976) The Selfish Gene. Oxford University Press; 2nd edition, December 1989 ISBN 0-19-217773-7.
Descartes (1637) Discourses Part V
Dupre, J. (1993) The Disorder of Things. Harvard University Press.
Nagel, E. (1961) The Structure of Science. New York.
Ruse, M. (1988) Philosophy of Biology. Albany, NY.
Dennett, Daniel. (1995) Darwin's Dangerous Idea. Simon & Schuster. ISBN 0-684-82471-X.
Alexander Rosenberg (2006) Darwinian Reductionism or How to Stop Worrying and Love Molecular Biology. University of Chicago Press.

External links

John Dupré: The Disunity of Science, an interview at the Galilean Library covering criticisms of reductionism.

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