I. Definition

“It all boils down to . . .”

Atoms? Signals in the brain? Yin and yang? Two kinds of people? Economics?

How many times have you heard someone say that everything “just boils down to” one or a few simple things?  That, in a nutshell, is reductionism.  Or more technically speaking, the claim that the properties of any complex and varied phenomenon can be explained in terms of the dynamics of some set of fewer more basic elements.

There are many kinds of reductionism, especially in science and philosophy, some of them clearly correct and useful, such as the reduction of biological to chemical processes, and others quite controversial—such as the reduction of mind to matter. Here are some examples of popular or famous reductions:

  • The Greek Democritus’ reduction of everything to atoms
  • The New Age / Physics reduction of everything to oscillating energy
  • The reduction of psychological illness to brain chemistry
  • The reduction of personality to four or five dimensions such as in the Myers-Brigg system or the “Big five”

These are all theoretical reductions, e.g. reducing culture to the effects of geography and climate, reducing consciousness to brain activity, or reducing, history to economics.

There are also:

  • Ontological reductionism: A philosophical affair–reducing “being” to one category, usually, “everything is matter,” or “everything is mind.” Although recently, an interesting third options has become, “everything is information.”
  • Methodological reductionism: A practical affair—a useful, working, reduction, such as reducing people to their economic needs and productivity in economic theory.

As you can see from these examples, reductionism is a huge aspect of our culture’s world-view, which is not historically true of every culture, and it is one of the keys to our scientific and technological success. At the same time, it can be an overly simplistic, and potentially biased, way of viewing things, especially in the social sciences.

Philosophically, some controversial questions revolve around reductionism—is your mind reducible to biochemistry and electricity? What about consciousness? And what about synergy and emergence (see section six); do these phenomena mean that reductionism is incorrect, even in the physical sciences?


II. The History of Reductionism

The world started sprouting reductionist theories in philosophy, science, and religion during the latter half of the first millennium B.C.E. It was then that the Greek Democritus put forth his theory that everything is composed of indivisible units called atoms.  Many other Greek theories could be interpreted as reductionism as well—Heraclitus’ statement that “all is change,” Euclid and Pythagoras’ reduction of space and shape to lines and angles, and the theory of the four elements—earth, air, fire, and water (which appeared in many ancient cultures).

Similarly, several forms of reductionism are recorded in the East around this time.  Chinese Taoists reduced all events to combinations of yin and yang, which have many meanings, most fundamentally stillness or solidity (yin) versus motion or emptiness (yang).  Taoists also used a “five element” theory (earth, metal, water, wood, and fire), especially in medicine; the five elements where thought of as phases of energy or matter, somewhat like solid, liquid, gas, and radiation, and health was thought to depend on their balance in the body.

Meanwhile, the Buddha lived around 500 B.C.E promoting a philosophy in which all reality reduces to a form of consciousness – “the Buddha nature.”  This philosophy owed a lot to mystical Hinduism before it.

Western scientific reductionism didn’t develop again, at least in Europe, until after the Dark Ages ended in the Enlightenment and the Age of Reason.  Science, from the beginning, has grown, perhaps mainly, through methodological reductionism–looking at something in terms of how simpler elements combine to form a great variety of phenomena.  Some of the greatest triumphs of scientific reductionism include Newton’s theories of gravity and mechanics, describing all motion in the universe in terms of a few equations, and Darwin’s theory of evolution by natural selection, which explains the entire diversity and complexity of the biological world in terms of a few simple principles.

The success of scientific reductionism in the 18th and 19th centuries culminated in the widespread belief that all reality is reducible to the mechanics of energy, as described by physicists.  At the same time, a few scientific theories calling this reduction into question developed throughout the 20th century and are now in full bloom – quantum theory and complexity theory.

III. Controversies

Can mind be reduced to something else?  This might be the most controversial question in philosophy.  On the one hand, the academic scientific and philosophical establishment is committed to physicalist reductionism in general—the belief that physical stuff is all there is.  But at the same time, there are, arguably, no coherent theories of how consciousness can be physical, only theories about the brain-processes associated with consciousness.  Scientists are figuring out a lot about how different kinds of cognition correspond to brain-activity, but nobody really has a clue how brain-activity comes to have experiential properties.   The most popular theories fall into four main groups:

  • Mind-body dualism: Mind cannot be reduced to matter, nor vice-versa.
  • Epiphenomenalism: Consciousness is a non-functional side-effect of functional brain-activity, with no causal powers.
  • Eliminativism: Consciousness equals brain activity, period.
  • Mysterianism: This is an inherently unsolvable mystery.
  • Idealism: Everything is made of consciousness.

The subject is so subtle that it’s not always clear which of these labels best describes a particular theory of consciousness, but it’s clear that the scientific world generally assumes eliminativism—the reductionist theory that mind is brain activity, obeying the laws of physics we already know, and nothing more.

Most people who assume this reduction also assume that quantum mechanical processes are not important for the generation of consciousness. Quantum theory challenges reductionism regarding certain phenomena, and may have something to do with consciousness, but most thinkers don’t believe that it opens the door for any sort of non-physical consciousness; quantum theory is still a physical theory.  So, science and philosophy are both in a tough spot right now: We have a well-justified commitment to physical reductionism (called ‘physicalism’) yet we can’t explain the most universal datum of all—the fact that we have experiences!


IV. Famous Quotes about Reductionism

Quotation #1:

“The love of complexity without reductionism makes art; the love of complexity with reductionism makes science.” — Edward O. Wilson

This eloquent statement suggests that art relies on synergy—where combinations of elements have unpredictable properties.  And because, in art, the meaning of a musical note, or a painted line, depends on what’s around it; these are non-reductionist complexities.  In science, we try to explain complexity in terms of simple elements in predictable relationships, with predictable outcomes.

Quotation #2:

“There is a strong current in contemporary culture advocating ‘ holistic ‘ views as some sort of cure-all . . . Reductionism implies attention to a lower level while holistic implies attention to higher level. These are intertwined in any satisfactory description: and each entails some loss relative to our cognitive preferences, as well as some gain… there is no whole system without an interconnection of its parts and there is no whole system without an environment.” — Francisco Varela

This one comes from one of the founders of complexity theory, whose researchers attempt to understand the properties of complex systems, especially their amazing tendency to self-organize and produce emergent phenomena.  Such as how chemistry organizes into organisms, and organisms into ecosystems.  Varela, who has done a lot of concrete detailed research on these topics, tells us that reductionism and holism are both necessary to understand complex systems.

V. Types of Reductionism

To review, the three most general types are:

  • Ontological reductionism: reducing “being” to one substance, such as energy
  • Methodological reductionism: reducing a problem to simple elements, to solve it
  • Theory reductionism: claiming that something can be reduced to a combination of simpler things without losing knowledge or understanding

Here are some more specific forms of reductionism:

  • Psycho-physical reductionism: the reduction of mind to matter
  • Semantic decomposition: the reduction of meaning, in linguistics, to combinations of simple ideas like “be” and “go.”
  • The phenomenological reduction: a philosophical methodology — the reduction of observations to statements about “phenomenology,” a fancy word for experience.

VI. Reductionism versus Emergence

“The whole is greater than the sum of its parts.”  This describes emergence or synergy, perhaps the greatest challenges to reductionism.  Some phenomena which seem emergent include atoms, molecules, chemicals, life, mind, and society!  An emergent property manifests only when elements are combined, usually in large numbers.  Other examples include colors, musical chords, and personalities.  But, most of these things can be explained in terms of their parts, ideally; researchers frequently publish discoveries explaining emergent properties of nature with reductionism.

Nonetheless, many emergent properties have not yielded to reductionism, and some people feel there are good reasons to think they will not.  Perhaps nothing demonstrates inherent holism, like R. Buckminster Fuller’s “synergetic geometry.”  Fuller, the inventor of the geodesic dome and about 1,000 other things, showed how structures, like skeletons and buildings, could be stronger than the sum of their parts, due to effects that only appear when they’re put together in certain ways; the geodesic dome is an example, and you can see Bucky Fuller-inspired architecture everywhere nowadays.  Strangely, his principle of “tensional integrity” or “tensegrity” has somehow become the name of a recent school of new-age self-development, however Fuller was just a mathematician and engineer.

Quantum mechanics seems to demonstrate a more radical form of holism in which systems may have more definite properties than their constituents, which cannot be regarded separately without a loss of information.  But whether quantum holism matters above the sub-atomic scale is still a matter of controversy.

VII.  Reductionism in Popular Culture

Example #1:

The Myer-Briggs personality test:

Almost surely, you’ve been exposed to this popular form of psychological reductionism, in which all personalities can be understood in terms of four dimensions:  introversion versus extroversion, sensing versus intuition, thinking versus feeling, and judging versus perceiving.  Each personality is designated by a four letter code representing these categorizations; e.g., I’m an INTP, I think!

Example #2:

The Matrix:

The clearest representation of ontological reduction in pop culture is the vision of the world as made of computer code, in the Matrix films.  It’s a notable alternative to physicalism and idealism – the world as computation – which is also a real hypothesis about the world supported by some respectable scientists.


Which of the following is not a form of reductionism?





Which of the following is a criticism of reductionism?





What is the most philosophically problematic form of reductionism?





Which of the following phenomena seem to oppose reductionism?





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