Reductionism can mean either (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 strongly reflects a certain perspective on causality. In a reductionist framework, phenomena that can be explained completely in terms of relations between 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.
Reductionism does not preclude the existence of what might be called emergent phenomena, but it does imply the ability to understand those phenomena completely in terms of the processes from which they are composed. This reductionist understanding is very different from that usually implied by the term 'emergence', which typically intends that what emerges is more than the sum of the processes from which it emerges.
Religious reductionism generally attempts to explains religion by boiling it down to certain nonreligious causes. A few examples of reductionistic explanations for the presence of religion are: that religion can be reduced to humanity's conceptions of right and wrong, that religion is fundamentally a primitive attempt at controlling our environments, and that religion is a way to explain the existence of a physical world. Anthropologists Edward Burnett Tylor and James George Frazer employed some religious reductionist arguments. Sigmund Freud's idea that religion is nothing more than an illusion, or even a mental illness, and the Marxist view that religion is "the sigh of the oppressed," providing only "the illusory happiness of the people," are two other influential reductionist explanations of religion.
There is a certain degree of reductionism in the social sciences, which often try to explain whole areas of social activity as mere subfields of their own field. As an example, Marxist economists often try to explain politics as subordinated to economy, and sociologists sometimes see economy and politics as mere sub-spheres of society.
Types of reductionism
Theoretical reduction is the process by which one theory absorbs another. For example, both Kepler's laws of the motion of the planets and Galileo’s theories of motion worked out for terrestrial objects are reducible to Newtonian theories of mechanics, because all the explanatory power of the former are contained within the latter. Furthermore, the reduction is considered to be beneficial because Newtonian mechanics is a more general theory—that is, it explains more events than Galileo's or Kepler's. Theoretical reduction, therefore, is the reduction of one explanation or theory to another—that is, it is the absorption of one of our ideas about a particular thing into another idea.
Methodological reductionism is the position that the best scientific strategy is to attempt to reduce explanations to the smallest possible entities. Methodological reductionism would thus hold that the atomic explanation of a substance’s boiling point is preferable to the chemical explanation, and that an explanation based on even smaller particles (quarks and leptons, perhaps) would be even better.
Methodological reductionism, therefore, is the position that all scientific theories either can or should be reduced to a single super-theory through the process of theoretical reduction.
Ontological reductionism is the belief that reality is composed of a minimum number of kinds of entities or substances. This claim is usually metaphysical, and is most commonly a form of monism, in effect claiming that all objects, properties and events are reducible to a single substance. (A dualist who is an ontological reductionist would believe that everything is reducible to two substances - as one possible example, a dualist might claim that reality is composed of "matter" and "spirit".)
Reductionism and science
Reductionist thinking and methods form 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 implies that certain fields of study are based on areas that study smaller spatial scales or organizational units. While it is commonly accepted that the foundations of chemistry are based in physics, and microbiology is rooted in chemistry, similar statements become controversial when one considers less rigorously defined intellectual pursuits. 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 affect 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.
Daniel Dennett defends scientific reductionism—which he says is really little more than materialism—by distinguishing between this and what he calls "Greedy reductionism": the idea that every explanation in every field of science should be reduced to particle physics or string theory. Greedy reductionism, he says, deserves some of the criticism heaped on reductionism in general because the lowest-level explanation of a phenomenon, even if it exists, is not always the best way to understand or explain it.
Some strong reductionists believe that the behavioral sciences should become "genuine" scientific disciplines based on genetic biology, and on the systematic study of culture (see Richard Dawkins's concept of memes). In his book The Blind Watchmaker, Dawkins introduced the term "hierarchical reductionism" to describe the view that complex systems can be described with a hierarchy of organizations, each of which is only described in terms of objects one level down in the hierarchy. He provides the example of a computer, which under hierarchical reductionism is explained in terms of the operation of hard drives, processors, and memory, but not on the level of AND OR gates, or on the even lower level of electrons in a semiconductor medium.
Both Dennett and Steven Pinker argue that too many people who are opposed to science use the words "reductionism" and "reductionist" less to make coherent claims about science than to convey a general distaste for the endeavor, saying the opponents often use the words in a rather slippery way, to refer to whatever they dislike most about science. Dennett suggests that critics of reductionism may be searching for a way of salvaging some sense of a higher purpose to life, in the form of some kind of non-material / supernatural intervention. Dennett terms such aspirations "skyhooks," in contrast to the "cranes" that reductionism uses to build its understanding of the universe from solid ground.
Others argue that inappropriate use of reductionism limits our understanding of complex systems. In particular, ecologist Robert Ulanowicz says 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 built off a common foundation, which is usually axiomatic set theory. Ernst Zermelo was one of the major advocates of such a view; he also developed 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.
Reductionism in psychology
In Psychology there is a strong tendency to offer explanations in terms of Physiology or Neurology. While such explanations offer additional evidence for the theories they support, they are not fundamentally superior to the evidence provided by Empirical research and theoretical development within the science of psychology itself.
Ontological reductionism is the claim 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.
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.
Limits of reductionism
A contrast to the reductionist approach is holism or emergentism. Holism is the idea that things can have properties, (emergent properties), as a whole that are not explainable from the sum of their parts. The principle of holism was concisely summarized by Aristotle in the Metaphysics: "The whole is more than the sum of its parts".
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.
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. Symmetry breaking is an example of an emergent phenomenon. Nobel laureate P.W.Anderson used this idea in his famous paper in Science in 1972, 'More is different' to expose some of the limitations of reductionism. The limitation of reductionism was explained as follows. The sciences can be arranged roughly linearly in a hierarchy as particle physics, many body physics, chemistry, molecular biology, cellular biology, physiology, psychology and social sciences. The elementary entities of one science obeys the laws of the science that precedes it in the above hierarchy. But, this does not imply that one science is just an applied version of the science that precedes it. Quoting from the article, "At each stage, entirely new laws, concepts and generalizations are necessary, requiring inspiration and creativity to just as great a degree as in the previous one. Psychology is not applied biology nor is biology applied chemistry."
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.
Free will and religion
Philosophers of the Enlightenment worked to insulate human free will from reductionism. Descartes separated the material world of mechanical necessity from the world of mental free will. German philosophers introduced the concept of the "noumenal" realm that is not governed by the deterministic laws of "phenomenal" nature, where every event is completely determined by chains of causality. The most influential formulation was by Immanuel Kant, who distinguished between the causal deterministic framework the mind imposes on the world—the phenomenal realm—and the world as it exists for itself, the noumenal realm, which included free will. To insulate theology from reductionism, 19th century post-Enlightenment German theologians moved in a new direction, led by Friedrich Schleiermacher and Albrecht Ritschl. They took the Romantic approach of rooting religion in the inner world of the human spirit, so that it is a person's feeling or sensibility about spiritual matters that comprises religion.
Benefits of reduction
An ontological reduction reduces the number of ontological primitives that exist within our ontology. Philosophers welcome this, because every ontological primitive demands a special explanation for its existence. If we maintain that life is not a physical property, for example, then we must give a separate explanation of why some objects possess it and why others do not. This is more often than not a daunting task, and such explanations often have the flavor of ad hoc contrivances or deus ex machina. Also, since every ontological primitive must be acknowledged as one of the fundamental principles of the natural world, we must also account for why this element in particular should be considered one of those underlying principles. (To return to an earlier example, it would be extremely difficult to explain why planets are so fundamental that special laws of motion should apply to them.) This is often extremely hard to do, especially in the face of our strong preference for simple explanations. Pursuing ontological reduction thus serves to unify and simplify our ontology, while guarding against needless multiplication of entities in the process.
At the same time, the requirements for satisfactorily showing that one thing is reducible to another are extremely steep. First and foremost, all features of the original property or object must be accounted for. For example, lightning would not be reducible to the electrical activity of air molecules if the reduction explained why lightning is deadly, but not why it always seeks the highest point to strike. Our preference for simple and unified explanations is a strong force for reductionism, but our demand that all relevant phenomena be accounted for is at least as strong a force against it.
Alternatives to reductionism
In recent years, the development of systems thinking has provided methods for tackling issues in a holistic rather than a reductionist way, and many scientists approach their work in a holistic paradigm. When the terms are used in a scientific context, holism and reductionism refer primarily to what sorts of models or theories offer valid explanations of the natural world; the scientific method of falsifying hypotheses, checking empirical data against theory, is largely unchanged, but the approach guides which theories are considered. The conflict between reductionism and holism in science is not universal—it usually centers on whether or not a holistic or reductionist approach is appropriate in the context of studying a specific system or phenomenon.
In many cases (such as the kinetic theory of gases), given a good understanding of the components of the system, one can predict all the important properties of the system as a whole. In other cases, trying to do this leads to a fallacy of composition. In those systems, emergent properties of the system are almost impossible to predict from knowledge of the parts of the system. Complexity theory studies such systems.
Alfred North Whitehead set his metaphysical thinking in opposition to reductionism. He refers to this as the 'fallacy of the misplaced concreteness'. His scheme set out to frame a rational, general understanding of things, that was derived from our reality.
The reductionist strategy or any method of simplification in scientific disciplines risks overlooking or negating awareness that already exists. Chaos theory, the concept of entropy in study of chemistry, and the Heisenberg Uncertainty Principle in particle physics, all indicate the awareness and cognition of the world becomes more complex as the level of awareness of it increases.
Scientists who use reductionist methods often take an approach that relies on contradicting previous contributions in their own context to science in order to validate a new theory, when sometimes there is no need to disprove existing theories in order to provide new insight. Proving a theory to be invalid and proving a new assumption to be true must both take place on their own merits. Scientific theories that are half-valid and half-invalid can be entirely brushed aside with reductionism, whereas with a holistic paradigm such as additivism, one can add the half-valid parts to updated assumptions. A reductionist would be less likely to view currently invalid theories as valid contributions in the context in which they were observed, utilized and presented, whereas a complexity theorist would be more likely to.
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.
- Multiple realizability was used as a source of arguments against reductionism.
- Philosophy of Mind
- Physical ontology
- Systems theory
- Symmetry breaking
- ^ See e.g. Reductionism in the Interdisciplinary Encyclopedia of Religion and Science.
- ^ Strenski, Ivan. "Classic Twentieth-Century Theorist of the Study of Religion: Defending the Inner Sanctum of Religious Experience or Storming It." Pages 176-209 in Thinking About Religion: An Historical Introduction to Theories of Religion. Malden: Blackwell, 2006.
- ^ For the Marx citation, see Opium of the people
- ^ "" Interview with Third Way magazine in which Richard Dawkins discusses reductionism and religion, February 28, 1995
- ^ R.E. Ulanowicz, Ecology: The Ascendant Perspective, Columbia University Press (1997) (ISBN 0-231-10828-1)
- ^ AAAS 1998 (no title)[dead link]
- ^  R. Gregory Taylor, "Zermelo, Reductionism, and the Philosophy of Mathematics". Notre Dame Journal of Formal Logic, Vol. 34, No. 4 (Fall 1993)
- ^  Michael Silberstein, John McGeever, "The Search for Ontological Emergence", The Philosophical Quarterly, Vol. 49, No. 195 (April 1999), (ISSN: 0031-8094).
- ^  Michael Ruse, "Do Organisms Exist?", Amer. Zool., 29:1061-1066 (1989)
- ^ P.B. Andersen, C. Emmeche, N.O. Finnemann, P.V. Christiansen, Downward Causation: Minds, Bodies and Matter, Aarhus University Press (ISBN 87-7288-814-8) (2001)
- ^ http://pespmc1.vub.ac.be/Einmag_Abstr/AJuarrero.html - A. Juarrero, Causality as Constraint
- ^ Beyond Reductionism: Reinventing the Sacred by Stuart Kauffman
- ^ http://personal.riverusers.com/~rover/RedRev.pdf A. Scott, Reductionism Revisited, Journal of Consciousness Studies, 11, No. 2, 2004 pp. 51-68
- ^ Link Anderson, P.W. (1972). "More is Different". Science 177 (4047): 393–396. Bibcode 1972Sci...177..393A. doi:10.1126/science.177.4047.393. PMID 17796623.
- ^ Downward Causation
- ^ Paul Guyer, "18th Century German Aesthetics," Stanford Encyclopedia of Philosophy
- ^ Philip Clayton and Zachary Simpson, eds. The Oxford Handbook of Religion and Science (2006) p 161
- ^ Dossey, Larry. Reinventing Medicine: Beyond Mind-Body to a New Era of Healing. (ISBN 0-06-251622-1) HarperSanFrancisco. (1999)
- ^ S. E. Jørgensen, Integration of Ecosystem Theories: A Pattern, 3rd ed. Kluwer Academic Publishers, (ISBN 1-4020-0651-9) (2002) Chapters 1 & 2.
- Dawkins, Richard (1976), The Selfish Gene. Oxford University Press; 2nd edition, December 1989.
- Descartes (1637), Discourses, Part V.
- Dupre, John (1993), The Disorder of Things. Harvard University Press.
- Jones, Richard H. (2000), Reductionism: Analysis and the Fullness of Reality. Bucknell University Press. (For the general reader.)
- Laughlin, Robert (2005), A Different Universe: Reinventing Physics from the Bottom Down. Basic Books.
- Nagel, Ernest (1961), The Structure of Science. New York.
- Ruse, Michael (1988), Philosophy of Biology. Albany, NY.
- Dennett, Daniel. (1995) Darwin's Dangerous Idea. Simon & Schuster.
- Fritjof Capra (1982), The Turning Point.
- Alexander Rosenberg (2006), Darwinian Reductionism or How to Stop Worrying and Love Molecular Biology. University of Chicago Press.
- Steven Pinker (2002), The Blank Slate: The Modern Denial of Human Nature. Viking Penguin.
- Stephen Weinberg (1992), Dreams of a Final Theory: The Scientist's Search for the Ultimate Laws of Nature, Pantheon Books.
- Steven Weinberg (2002) describes what he terms the culture war among physicists in his review of A New Kind of Science.
- Eric Scerri The reduction of chemistry to physics has become a central aspect of the philosophy of chemistry. See several articles by this author.
- Lopez, F., Il pensiero olistico di Ippocrate. Riduzionismo, antiriduzionismo, scienza della complessità nel trattato sull'Antica Medicina, vol. IIA, Ed. Pubblisfera, Cosenza Italy 2008.
- Ingo Brigandt and Alan Love, "Reductionism in Biology" in: The Stanford Encyclopedia of Philosophy.
- John Dupré: The Disunity of Science-- an interview at the Galilean Library covering criticisms of reductionism.
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