Reductionism and Holism: Two Sides of the Perception of Reality

Reductionism as Philosophy

Reductionism is a philosophical tenet which states that by analyzing a system to its ultimate component parts, we will be able to unravel it at deeper and deeper levels. It is the process of reducing any feature of the perceived world to its final elements with the hope of exposing all the secrets about the phenomenon.  In other words, the world and its workings will be best understood - indeed can only be understood - in terms of the ultimate constituents and forces which give rise to it.

Reductionism, explicitly or implicitly, has been an important and powerful guiding principle of the scientific enterprise for a very long time. With the rise of modern science in the seventeenth century, physicists introduced certain key concepts like mass, velocity, acceleration, force, and momentum in terms of which they could describe and explain a whole range of natural phenomena.  In the eighteenth century, this framework developed into the enormously powerful and fruitful field of classical mechanics.  A spectacular application of classical mechanics was the discovery of the planet Neptune using only paper and pencil, i.e. from theoretical calculations alone, from the observed discrepancies in the motion of Uranus.

In the 19th century, this was extended to electromagnetic phenomena. By introducing the notions of electric charge and field, a whole new range of phenomena could be adequately explained.  A significant result of this framework was the discovery, again on paper, of electromagnetic waves, a discovery which may well be regarded as the most spectacular achievement of the human mind in all of history.

Just as, in the 17th century, Descartes had reduced the entire physical universe to matter and motion, in the scientific paradigm of the 19th century, ultimately in the world there is only matter and energy in space transforming in time.  In other words, every phenomenon can be reduced, in principle, to energy transformations and their impacts of material entities in the arena of space.

It was the unprecedented successes in the human capacity to explain and predict that inspired most practitioners of science to the conviction that all observed features of the phenomenal world can be ultimately reduced to atoms and molecules and the forces and principles acting on them, at least as far as the physical world was concerned. 

A similar thing happened in biology also.  Practically every explanatory success in biology at the micro level - from circulation and secretion to osmosis and cell structure was grounded in the principles of physics and chemistry.  This prompted thinkers like Carl Ludwig and Hermann von Helmholtz to assert, not unlike La Mettrie and other thinkers in the early eighteenth century, that the entire range of phenomena pertaining to life may be understood and explained in terms of physics, chemistry, and their mechanistic framework.

Indeed, the term reductionism was coined by biologists.  Its practical (i.e.  results-producing) successes drew more and more scientists to this respectable school of thought within the scientific establishment.  Reductionism holds that some day we can explain chemistry, biology, and even psychology through the principles of fundamental physics.  This conclusion seemed obvious to some of the founders of Quantum Mechanics in the 1920s.

A climax of the reductionist quest is to be found in the so-called Standard Model and the dreams of a final TOE: Theory Of Everything, whose goal is to reduce the entire phenomenal world to one single equation:  in other words, to formulate a single all-embracing principle of which the range and variety of the entire universe are but inevitable consequences.

While it is possible to break down a system into its component parts and functions, it is difficult to see how those parts and functions add up to what is actually observed.  This is often illustrated with a simple example.  Two atoms of hydrogen and one of oxygen are very different in aspect and properties from the water molecule that results by their combination.  The bonds and structures of molecules give rise to properties that are seldom found in their component atoms.

Thus, reductionism reveals to us what are underneath everything, but says little about how they converge into something very different.  In other words, reductionism reveals the being part of the world, but hardly throws any light on the becoming aspect.

This is why uncompromising reductionism is sometimes pejoratively characterized as scientism.  This is why the general trend during the past few decades has been to criticize, not to say condemn reductionism as inadequate at the very least, and misleading at worst.  Moreover, while reductionism may seem reasonable for the physical world, its application to the biological and the human world is not as convincing to many philosophers, theologians, and commentators on science.  Alan Wallace noted that "reducing the human being to a complex of atoms governed entirely by the laws of physics seems an article of faith rather than a scientific fact."

There is an implicit assumption in some of the criticisms that scientists somehow embrace reductionism with the same zeal or unshakable conviction as other systems do about the infallibility of scriptures.  It must be emphasized that reductionism has an appeal for only one reason:  it has given rise to an incredibly rich harvest of significant results.  Most molecular biologists and neuroscientists who write technical papers in peer-reviewed journals, and contribute to new breakthroughs in science work in their fields from this perspective.  Yet, as and when other approaches arise in whatever context, if and when a non-reductionist approach turns out to be useful in providing explanations of observed phenomena, the world of science does and will adopt it.

Reductionism as a philosophy of nature may be clarified by emphasizing the difference between what Steven Weinberg called petty and grand reductionism.  In the first kind, one maintains that the properties of most things can be explained in terms of the properties of their constituents.  It is true that this cannot resolve all the problems of science.  That is to say, not all the observed properties of complex systems can be reduced to specific properties of its simpler constituents.

However, this is not what physicists generally mean by reductionism. They mean rather the view that everything can be explained only in terms of clear laws and principles, often mathematically expressible, and that ultimately all the known laws and principles can be reduced (traced) to a minimum number of laws and principles.  This may be called grand reductionism.

When one undertakes to explain any aspect of the world in a coherent and systematic way, one assumes that the world functions in coherent and systematic ways.  Grand reductionism is an affirmation of this assumption.  One either adopts it and goes on with the job of accounting for various aspects of observed reality, or one abandons it and does something else.  In this sense, one may say that grand reductionism is at the root of all scientific explanatory endeavors.

Furthermore, science knows that there are any number of problems whose solution can be found without going to the root causes or fundamental laws.  Weinberg cites the example of weather prediction where one speaks of cold fronts, warm fronts, and thunderstorms, which are useful parameters.  Indeed, these are far more helpful than the molecular motion of the gases, the laws of heat exchanges, and the like which are ultimately responsible for the weather patters.  Likewise, we can solve problems in projectile motion without a theory of gravitons, and we can device electrical circuits for a home without going into Maxwell's equations or quantum electrodynamics.  A physician might treat a patient on the basis of the reported head-aches, stomach-aches, inability to read small letters, etc., even though all these can be traced to the basic principles and fundamental constituents that keep the body functioning.


Holism is a philosophical view which states that by considering the whole picture one gets a deeper and more complete view of a situation than by analyzing it into its component parts.  What this means is that a system consisting of several recognizable parts has properties which are not present in any of is component parts.  The view that a forest presents is different from that of each of its individual trees.

It takes time, effort, and careful analysis and search to find out the details of the components, that is to say, to establish the reductionist basis of a system.  There is hardly a system without holistic properties.  More often that not, what we experience is the holistic aspect of a system.  From this perspective, the process of analysis may lead us to the reductionist components, but on the way some aspect of the whole is lost.  That is why when we put back the parts together we don't always get the whole.

There are, in fact, three kinds of holism.  The first is a vision, an all-embracing view of a system as a whole.  The grand view of a forest as a whole is different from the view of a single tree.  This kind of holism is interesting, satisfying, and meaningful. It therefore plays a part in art, literature, and philosophy.  But since it rarely explains anything, we do not find in science.

One of the intrinsic features of biological systems is that they are often interconnected. No organism can live by itself, and no species is completely independent of every other.  Biological holism arises from the fact that not only is the evolution of everything affected by its environment, but its very survival depends on it.

Charles Darwinstressed the importance of competition among species.  Today biologists also remind us that "the structure of every organic being (organism) is related, in the most essential yet often hidden manner, to that of all other organic beings, with which it comes into competition.”  In his fascinating book The Botany of Desire, Michael Pollan elaborates on how co-evolution occurs "where there is dominant interdependence between long-associated species within an ecosystem."

The other kind of holism refers to the fact that when A and B are combined, the resulting C has more properties than what each of the components bring, indeed that it may have properties which neither of them had when they were separate.  We may call this non-linear holism. One of the tasks of science is to explain how this comes about.


You can take a sentence and break it up into the words and letters constituting it. But the sound and meaning that emerge from putting together those letters in that particular order are very different from the form and sound of those letters taken individually. In other words, though the whole is made up of several parts, it is not always simply equal to the sum of its parts.

This is also true in the material world.  One reason we get a more complete picture from the holistic view is that in most complex systems, the whole is invariably greater than the sum of its parts.  Nonlinear Holism is explained through the notion of emergence by saying that in the natural world there are two kinds of occurrences:  those that arise from the properties of the individual entities, and those that arise from the combination of individual entities.  In other words, there are not only consequent properties, by virtue of the properties of the constituent parts in a complex system, but also emergent properties which were not there at all in the constituent parts.  Thus light is emitted as a result of the properties of atoms: electronic transition within them.  On the other hand, surface tension arises because of the configuration of the atoms in a mass of water.

In this view, processes in the brain occur because of the properties of neurons.  But consciousness as a phenomenon is an emergent property resulting from neural networks. Some emergent properties are the direct result of interaction between two complex entities.  The tongue by itself does not experience sweetness.  Sugar by itself is not sweet. Tongue plus sugar leads to sweetness which is thus an emergent property.

It is important to distinguish between emergentism and creationism.  In emergentism, we get something more from something less.  In creationism we get something out of nothing.  In fact, emergentism as a worldview is presented as an alternative to the notion that something new can come all of a sudden in the world out of nowhere.

To explain what causes emergence, we may use the notion of information.  Information is a non-physical entity which governs the behavior of complex systems.  It directs the behavior of complex molecules.  In the current paradigm, when we have a complex system with some non-random structure, it is said to embody some information.  Information enables or directs the system to evolve or develop in specific ways.  In everyday experience, information helps s find our way to a destination.  At the gene level, the information in the DNA is what directs its behavior.

When we consider the behavior of matter and energy in the universe, we find that they are subject to the basic laws of physics.  Another way of looking at this is to say that matter and energy act on the basis of the information that is implicit in the laws of nature. We may call this first order information.

First order information enables and directs a goodly number of things to happen.  But such happenings occur in a blind and routine manner, with no purpose at all.

Next we may envisage a second order information which is at the basis of the biological world.  Second order information requires long and complex molecules.  The genes and biochemical processes occur from this kind of information.  There can be no biological world without the DNAs and RNAs in which are embedded a whole variety of second order information.  We recognize that with second order information is associated the capacity of replicating complex molecules as well as for purpose-driven behavior.

When molecules and complex structures develop with second order information, we have no longer the strict predictable course such as we find in the physical world, but possibilities for change in the original entities.  One result of such changes is the emergence of brain.  This very complex system becomes the source of a third order information which endows the system with the capacity for generating thoughts.  There is, as far as we know, no other system in the entire universe which has this capacity.

One may say that there is information about the universe that can be gathered by systems which are capable of third order information.  In other words, whereas information keeps the universe functioning, knowledge about the universe becomes a fourth order information which certain human brains are capable of unraveling.

Thus, information may be considered as a link between reductionism and holism.  Information keeps the world going.  First order information is at the root of the physical world, second order information is at the root of the biological world, and third order information is at the basis of the mental world.  All information is ultimately tied to the matter energy substrate of the universe, and thus has a reductionist basis.  On the other hand, it is fourth order information that leads to an awareness of all this, and thus reveals the interconnectedness among the countless individual cogs that keep the vast machinery running.

Review of ideas

From these considerations we may say the following:

Reductionism reveals that what seems to be smooth is in reality only an impression created by agglomeration of vast separate chunks: that there are mountains and valleys on the apparently perfect spherical lunar crystal.

Holism reveals that what seems like an unconnected heap of separate entities form a web of unity in which the constituents intertwine and form an integrated quilt.  As no creature on the planet is an island unto itself, no planet is unconnected to a star, nor a star to a galaxy.  Indeed every electron is entangled in some way with every other, for ultimately and in principles wave functions are non-localized spreads.

One may see there is an epistemologically significance in this:  When we focus on the reductionist and separateness aspect of the phenomenal world, we get one vision of reality.  When we focus on its holistic feature, we experience another vision of reality. Considering states or provinces in a country is a reductionist mode, while taking a nation as a whole is the holistic mode.  Each is relevant and important in its own context.

We also recognize that the more we focus on one, the more the other becomes blurred. This complementarity relationship in the Bohr sense between reductionism and holism is illustrated in the microcosm where the particle aspect of an entity like the electron or the proton, appears as a particle in its reductionist aspect, and as a wave in its holistic mode. Thus reductionism and holism may be regarded as two modes of apprehending reality, not unlike the two sides of a coin: each meaningful and satisfying in its own way, but neither is a complete description of what obtains in the world. From this perspective reductionism and holism are somewhat like the microscope and the telescope: two powerful instruments to explore the world, one revealing the smallest constituents of what makes up the world, while the other is sweeping the cosmic grandeur and makes us aware of the unity behind the diversity.

Likewise, it is fair to say that if science makes us understand the world through its methods of analysis, religion, through its all-encompassing mode, makes us see the human experience as a grand, rich, and unifying tapestry. When science focuses uniquely on the reductionist mode it can miss the grander vision of reality. When religion misses its grand holistic vision that sees the commonalty among the peoples of the world, it is reduced to a narrowness that is both petty and dangerous.

To assert that reductionism alone leads to understanding, or that it is very mistaken in its efforts to understand would be as much a half-truth as the claim that holism is what brings us true awareness or that it is merely old-fashioned metaphysical poetry.  

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