Holism versus Scientific Reductionism–Worldview Debate
A contrast to the reductionist approach is holism or emergentism. Holism is the idea that things can have properties, (emergent properties), as a whole that are not explainable from the sum of their parts. The principle of holism was concisely summarized by Aristotle in the Metaphysics: “The whole is more than the sum of its parts”.
The term greedy reductionism, coined by Daniel Dennett, is used to criticize inappropriate use of reductionism. Other authors use different language when describing the same thing.
The concept of downward causation poses an alternative to reductionism within philosophy. This view is developed and explored by Peter Bøgh Andersen, Claus Emmeche, Niels Ole Finnemann, and Peder Voetmann Christiansen, among others. These philosophers explore ways in which one can talk about phenomena at a larger-scale level of organization exerting causal influence on a smaller-scale level, and find that some, but not all proposed types of downward causation are compatible with science. In particular, they find that constraint is one way in which downward causation can operate. The notion of causality as constraint has also been explored as a way to shed light on scientific concepts such as self-organization, natural selection, adaptation, and control.
The idea that phenomena such as emergence and work within the field of complex systems theory pose limits to reductionism has been advocated by Stuart Kauffman. Emergence is strongly related to nonlinearity. The limits of the application of reductionism become especially evident at levels of organization with higher amounts of complexity, including living cells, neural networks, ecosystems, society, and other systems formed from assemblies of large numbers of diverse components linked by multiple feedback loops.
Nobel laureate P.W.Anderson used the idea that symmetry breaking is an example of an emergent phenomenon in his 1972 Science paper ‘More is different’ to make an argument about the limitations of reductionism. One observation he made was that the sciences can be arranged roughly in a linear hierarchy — particle physics, many body physics, chemistry, molecular biology, cellular biology, physiology, psychology, social sciences — in that the elementary entities of one science obeys the laws of the science that precedes it in the hierarchy; yet this does not imply that one science is just an applied version of the science that precedes it. He writes that “At each stage, entirely new laws, concepts and generalizations are necessary, requiring inspiration and creativity to just as great a degree as in the previous one. Psychology is not applied biology nor is biology applied chemistry.”
Disciplines such as cybernetics and systems theory embrace a non-reductionist view of science, sometimes going as far as explaining phenomena at a given level of hierarchy in terms of phenomena at a higher level, in a sense, the opposite of a reductionist approach.
Free will and religion
Philosophers of the Enlightenment worked to insulate human free will from reductionism. Descartes separated the material world of mechanical necessity from the world of mental free will. German philosophers introduced the concept of the “noumenal” realm that is not governed by the deterministic laws of “phenomenal” nature, where every event is completely determined by chains of causality. The most influential formulation was by Immanuel Kant, who distinguished between the causal deterministic framework the mind imposes on the world—the phenomenal realm—and the world as it exists for itself, the noumenal realm, which included free will. To insulate theology from reductionism, 19th century post-Enlightenment German theologians moved in a new direction, led by Friedrich Schleiermacher and Albrecht Ritschl. They took the Romantic approach of rooting religion in the inner world of the human spirit, so that it is a person’s feeling or sensibility about spiritual matters that comprises religion.
The anti-reductionist takes this position as a minimum requirement upon the reductionist: “What is unclear is how the pre-theoretical intuitions [for example, of free will] are to be accommodated theoretically within favored analyses… At the very least the anti-reductionist is owed an account of why the intuitions arise if they are not accurate.”