Reductionism and holism are complementary thinking styles. One seeks meaning from an investigation of the parts, while the other seeks meaning from an investigation of the whole. They are the yin and yang of systems thinking.

For over three hundred years we have relied on reductionist thinking to make sense of the world. Reductionism was first postulated by the French philosopher René Descartes in 1637. Reductionism is an approach to understanding the nature of a complex problem by reducing it to the interaction of its parts. Each part is examined and understood, and by understanding the parts the whole is understood.

‘The whole is the sum of its parts’

Holistic thinking is the opposite of reductionist thinking. The term holism was pioneered by the South African statesman Jan Smuts in his book Holism and Evolution. Smuts described holism as the tendency in nature to form wholes that are greater than the sum of parts through creative evolution. Although Smuts applied the concept of holism to evolution, the idea has ancient roots, going back at least as far as the Ancient Greeks.

‘The whole is more than the sum of its parts’ – Aristotle

Systems thinking works by applying the concept of a system to a problem. In doing so the problem can be assumed to have all the properties of a system. When a system’s properties are examined its true nature is revealed. Hence, the nature of a problem is revealed when its systemic properties are investigated.

Reductionism has served us well in our study of systems, but with the increasing pace of technological change and situations becoming increasingly complex, reductionism has begun to let us down. In fact, the Irish social philosopher Charles Handy, in his book The Age of Unreason declared that reductionism is the sin of modern life; by reducing things to their component parts all too often the meaning of the message in the wood is missed by a minute examination of its trees.

Holism on the other hand seeks to understand the meaning of the message in the wood by understanding the properties of the whole. Holism strives to understand the properties of the whole not the parts.

Holism helps us understand the fundamental purpose of the system and its behaviour, whereas reductionism helps us examine the nature of its architecture and components. Both thinking styles have their place in our study of systems.