Holism is usually defined as entities existing in nature, wholes, which are irreducible to the mere sum of their parts. Holism is often referred to as a theory or doctrine according to which a whole cannot be analyzed without residue into the sum of its parts or reduced to discrete elements. Wholes exist at every level: a molecule can be 'atomized' or it can be studied as an entity unto itself, as a whole. Molecular science is, then, more holistic than atomic science. Complete reductionism would allow only the atomic or even the sub-atomic level as worthy of analysis. Reductionism and holism are complementary, and both are needed to better understand the earth and its complexity.

In biology, ecology is the field most engaged with a holistic approach. Ecologists have developed a number of concepts, strategies and techniques to help their work to be holistic. Holism in ecology...