Reductionism

Descartes held that non-human animals could be reductively explained as automata — De homines 1622.

Reductionism is a philosophy or approach to understanding the nature of complex things by reducing them to the interactions of their parts, simpler or more fundamental things. This can be said of objects, phenomena, explanations, theories, and meanings.

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.

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.

Varieties of reductionism

There are several generally accepted types or forms of reduction in both science and philosophy:

Ontological reductionism

Main article: Ontological reductionism

Ontological reduction is the idea that everything that exists is made from a small number of basic substances that behave in regular ways (compare to monism). There are two forms of ontological reductionism: token ontological reductionism, and type ontological reductionism. 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.

Methodological reductionism

Main article: Methodological reductionism

Methodological reductionism is the idea that developing an understanding of a complex system's constituent parts (and their interactions) is the best way to develop an understanding of the system as a whole.

Methodological individualism

Main article: Methodological individualism

Methodological individualism protends sociological inquiry based on individual decisions.

Theoretical reductionism

Theoretical reductionism has two definitions. In the first definition it is the idea that the terms of a theory of science A referring to objects at a higher level of complexity than the objects of science B can be replaced by the terms of science B. In the second definition of theoretical reductionism the older theories or explanations are not generally replaced outright by new ones, but new theories are refinements or reductions of the old theory into more efficacious forms with greater detail and explanatory power. The older theories are supposedly absorbed into the newer ones and they can be deductively derived from the latter.

Scientific reductionism

Main article: Scientific reductionism

Scientific reductionism has been used to describe all of the above ideas as they relate to science, but is most often used to describe the idea that all phenomena can be reduced by scientific explanations. It is useful to note in addition that there are no explicit theories that reject token ontological reduction of biological items to chemical items, or that reject token ontological reduction of chemical items to physics items. Also by the middle of the 20th century the empirical results made extremely implausible the view that there are fundamental forces activated only by highly complex configurations of subatomic particles.

Linguistic reductionism

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).

Greedy reductionism

Main article: Greedy reductionism

Greedy reductionism is a term coined by Daniel Dennett to condemn those forms of reductionism that try to explain too much with too little.

Eliminativism

Main article: Eliminativism

Eliminativism is sometimes regarded as a form of reductionism. Eliminativism is the idea that some objects referred to in a given theory do not exist. Accordingly, the terms of that theory are abandoned or eliminated. Eliminativism is often regarded as a form of reductionism, since the eliminated theory is at some point replaced by a theory referring to the objects that were not eliminated. For example, the theory that some diseases are caused by occupation by a demon has been eliminated. Accordingly it has been reduced by elimination to other theories about the causes of diseases.

Other typologies are also possible. For example, Richard Jones in a systematic study of reductionism in philosophy, the natural sciences, the social sciences and religion differentiates five types: substantive, structural (causal), theoretical, conceptual (descriptive), and methodological. He criticizes reductionism and advocates the importance of emergence. John Dupre also advocates antireductionism.

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".

In Science

Phenomena such as emergence and work within the field of complex systems theory pose limits to reductionism. Emergence is strongly related to nonlinearity. The limits 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 Religion

Outside the field of strictly philosophical discourse, the best known denial of reductionism is religious belief, which, in most of its forms, assigns supernatural original causes to phenomena. In this approach, even if a given system operates by strictly reductionistic causes and effects, 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.

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.

See also

• Holism
• Emergentism
• Scientific reductionism
• Theology
• Aristotle
• Philosophy of Mind
• Physicalism
• Systems theory

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.
• Jones, R. (2000) Reductionism: Analysis and the Fullness of Reality. Bucknell 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.