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Reductionism in practice: a duck is the sum of a bunch of gears and a big hose.
Thinking hardly
or hardly thinking?

Icon philosophy.svg
Major trains of thought
The good, the bad,
and the brain fart
Come to think of it

Reductionism is the philosophical position that a complex phenomenon can be described ultimately by the component pieces that make up that phenomenon. Reductionism can be applied to almost anything, whether it is a physical system, a process, a thought, or a living creature. Many argue that the scientific method relies heavily on reductionism, and science's ability to accurately model reality is linked to how much it can be reduced. Others have argued that certain systems demonstrate emergent properties that are above and beyond the component pieces of the system. Many attempts are being developed to figure out a way to test for the existence of and ultimately rigorously study these kinds of phenomena.

Ontological vs. methodological reductionism[edit]

Two forms of reductionism are often contrasted. Methodological reductionism refers to the use of a methodology that seeks to describe or explain a phenomenon in terms of its constituent pieces. Ontological reductionism makes the stronger, metaphysical claim that the phenomenon itself doesn't exist, but only its constituent parts do. This is sometimes referred to as "eliminativism".

Unification of science by means of reductionism[edit]

Math is really logic. Logic is really philosophy. Philosophy is really psychology. Psychology is really biology. Biology is really Chemistry. Chemistry is really physics. Physics is really math.
—Ben Mordecai[1]

Various schemes to subsume what are sometimes known as the "special sciences" into a "fundamental" or "general science" have been proposed throughout the history of science. The search for a "theory of everything" has been construed by some as a potential discovery that would unify and reduce all science to physics. This is pithily summed up by Ernest Rutherford's quip that "All science is either physics or stamp collecting."[2] This position is often ascribed to the "unity of science" movement associated with logical positivism, though not all the scientists and philosophers in this tradition held to a strict version of it.[3] Others have advocated collapsing the social sciences and humanities into biology, using evolution as unifying theory. (Or sometimes, the weaker claim that all the special sciences should be done using an evolutionary or biological approach.) This notion was popularized by Edward O. Wilson in his book Consilience: The Unity of Knowledge.[4] In Darwin's Dangerous Idea, Daniel Dennett used evolution as a unifying theory but takes a different approach by re-conceptualizing natural selection as an algorithmic process that can be applied to all fields of knowledge.[5]

Arguments against reductionism[edit]

Due to the success of reductionist programs in science, it has often been taken that (by induction) all scientifically-oriented research ought to be reductionist in nature. A number of arguments have been made against this line of thinking, proposing methodologies from ones that fully integrate reductionism but constrain its applicability to some degree to ones that reject reductionism entirely.

The majority of states of matter in quantum theory have holistic features, but these can be analysed by studying correlations of repeated measurements on the components. Thus although the world actually is holistic, it's not so holistic that reductionist techniques cannot be applied.[6]

Anti-reductionism and holism[edit]

Anti-reductionist arguments are often associated with holism, although this is not necessarily the case. The term "holism" was originally coined by Jan SmutsWikipedia to refer to the co-evolution between parts and wholes. He defined "wholism" as the concept that the whole is more than the sum of its parts.[7]

In philosophy of mind, Jerry Fodor argued against reductionism (extending an argument made by Hilary Putnam) on the grounds of multiple realizability, i.e., that multiple physical kinds may underlie a single mental state.[8][9] But Fodor has also argued against holism, claiming that it would make scientific psychology impossible because it would prevent any generalizations being made about mental states.[10]

Another common angle from which to attack reductionism is to point out failed attempts to reduce certain special sciences. In biology, this usually involves arguing from the lack of a reductive account of evolution or genetics in terms of molecular biology.[11] In the behavioral and cognitive sciences, the lack of a reductive account of the "hard problem" of consciousness is used as ammo for anti-reductionist arguments.[12] (Though some deny that the hard problem exists.)

Anti-science rhetoric[edit]

"Reductionism" is sometimes used as a euphemism in anti-science rhetoric. For example, a common accusation from alternative medicine practitioners is that real doctors practice reductionism and refuse to consider the "whole". This is untrue; proper medical practice is to look at all possible disease vectors when diagnosing a patient, including the possibility of psychosomatic illness.[note 1] Ironically, practitioners such as many chiropractors think one can reduce a diagnosis to the spine only. (When one's only tool's a hammer…)

Quite often, this comes down to a (sometimes cynical) failure to distinguish between ontological and methodological reductionism.

See also[edit]

External links[edit]


  1. Some quacks use this to suggest that the "whole patient" is not treated because there is little or no personal interaction with the dreaded "allopathic" doctor. While the lack of personal interaction is an acknowledged problem of modern medical practice, it is a consequence of economics and logistical complexity, not of flawed methodology as quacks allege. Anti-reductionism here serves to frame legitimate practical problems as evidence of something more sinister; e.g., quacks claim scientists face these issues not because their solutions are complicated and they deal with a high number of patients, but because they're blinded by reductivist ideology. And, for good measure, quacks turn what is, in reality, evidence of their fraudulent practice into a virtue!


  1. What's a good ending for 'Biology is really chemistry. Chemistry is really physics. Physics is really math. Math is really hard'? - Quora
  2. Undisciplined Science, Brian Hayes, American Scientist
  3. See The Unity of Science in the SEP
  4. See the Wikipedia article on Consilience.
  5. See the Wikipedia article on Darwin's Dangerous Idea.
  6. Quantum Theory from First Principles: An Informational Approach by Giacomo D'Ariano et al. (2017) Cambridge University Press. ISBN 9781107043428.
  7. Smuts' Holism and Evolution, Dave Marsay
  8. Jerry Fodor. Special Sciences (Or: The Disunity of Science as a Working Hypothesis. Synthese, Vol. 28, No. 2 (Oct., 1974), pp. 97-115
  9. See also SEP's entry for Multiple Realizability
  10. Ernest Lepore and Jerry Fodor. Precis of Holism: A Shopper's Guide. Philosophy and Phenomenological Research Vol. 53, No. 3 (Sep., 1993), pp. 637-640
  11. See SEP's entry for Reductionism in Biology
  12. See the IEP's entry for The Hard Problem of Consciousness.