Holism (from ὂλος holos, a Greek word meaning all, whole, entire, total) , is the idea that natural systems (physical, biological, chemical, social, economic, mental, linguistic, etc.) and their properties, should be viewed as wholes, not as collections of parts. This often includes the view that systems somehow function as wholes and that their functioning cannot be fully understood solely in terms of their component parts.
The term holism was coined in 1926 by Jan Smuts. Reductionism is sometimes seen as the opposite of holism. Reductionism in science says that a complex system can be explained by reduction to its fundamental parts. For example, the processes of biology are reducible to chemistry and the laws of chemistry are explained by physics.
Social scientist and physician Nicholas A. Christakis explains that “for the last few centuries, the Cartesian project in science has been to break matter down into ever smaller bits, in the pursuit of understanding. And this works, to some extent…but putting things back together in order to understand them is harder, and typically comes later in the development of a scientist or in the development of science.”
General scientific status
In the latter half of the 20th century, holism led to systems thinking and its derivatives, like the sciences of chaos and complexity. Systems in biology, psychology, or sociology are frequently so complex that their behavior is, or appears, “new” or “emergent”: it cannot be deduced from the properties of the elements alone.
Scientific holism holds that the behavior of a system cannot be perfectly predicted, no matter how much data is available. Natural systems can produce surprisingly unexpected behavior, and it is suspected that behavior of such systems might be computationally irreducible, which means it would not be possible to even approximate the system state without a full simulation of all the events occurring in the system. Key properties of the higher level behavior of certain classes of systems may be mediated by rare “surprises” in the behavior of their elements due to the principle of interconnectivity, thus evading predictions except by brute force simulation. Stephen Wolfram has provided such examples with simple cellular automata, whose behavior is in most cases equally simple, but on rare occasions highly unpredictable.
Complexity theory (also called “science of complexity“), is a contemporary heir of systems thinking. It comprises both computational and holistic, relational approaches towards understanding complex adaptive systems and, especially in the latter, its methods can be seen as the polar opposite to reductive methods. General theories of complexity have been proposed, and numerous complexity institutes and departments have sprung up around the world. The Santa Fe Institute is arguably the most famous of them.