“Reductionism” is something of a dirty word in nursing and other health sciences. To call a theory “reductionist” is to criticize it as limited and uninteresting. Nurse scholars tend to view nursing as holistic, and therefore rejecting a theory because it is reductionist puts it outside the domain of nursing scholarship. This argument was very important during the rise of nursing qualitative research in the 1980s, and it continues to appear in discussions about the character of nursing science.
But what does “reductionism” mean? What makes a theory reductionist? And why is reductionism a bad thing? These questions are made more complex by the fact that “reductionism” is used in several different ways. It will go some way toward answering these questions if we can sort out some of the different things that people have meant by these terms.
Notice that the verb “reduce” typically implies a relationship. One thing (or sort of thing) is reduced to another. This means that we can gain some purchase on what reductionism amounts to if we begin by asking what is being reduced to what, and how are they related? In the context of scientific research, it is theories (or better, aspects of theories) that are described as reductionist. Hence it is a relationship among (aspects of) theories with which we will primarily be concerned. Moreover, questions of reduction typically involve a “higher” and “lower” level. The question is whether theories at the higher level can be reduced to those at the lower level.
“Reductionism” and “holism” are conceptually intertwined. At first glance they may seem to be contraries: to say that a theory is holistic is to deny that it is reductionistic, and vice versa. The vast literature in the philosophy of science shows that matters are not so simple. There are, of course, some extreme forms of reductionism and holism that do define the concepts in oppositional terms. To insist, for example, that the existence of the mind is completely independent from the existence of the body, as Descartes did, is a strong form of anti-reductionism (or holism) about the mental. It is opposed to a thoroughgoing materialism which insists that no minds exist, only brains. There are, however, a range of middle positions that relate mind and body, neither reducing one to the other nor insisting on their separation.
We will need to speak, then, of stronger and weaker forms of holism and reductionism. The strong forms of holism will hold that two domains (e.g. minds and bodies) are utterly distinct and independent; strong forms of reductionism will eliminate one domain by collapsing it into another (e.g. minds are nothing but brains). The weaker positions will hold that the two domains are distinct (thus denying strong reductionism) and that they depend on each other (thus denying strong holism).
One motivation for reductionism has been epistemological economy. To reduce one theory to another in this sense is to show that knowledge of one domain suffices for knowledge of another. Philosophers, scientists, and mathematicians have been interested in epistemological reduction because it promises to tighten up justifications.
Classical empiricism is reductionist in the epistemological sense. Empiricists hold that all knowledge arises from experience, and the classical empiricists (Locke, Berkeley, Hume) understood experience in terms of perceptual ideas. Elementary or simple experiences of color, shape, taste, sound, and so on formed the indubitable foundation for all other knowledge. Their project was to show how complex ideas could all be constructed from simple ones. Challenges arose for empiricists in areas where it was difficult to show that the concepts and judgments were constructions of simple ideas. Hume’s critique of causality can be understood as a struggle to understand how knowledge of causes can be reduced to knowledge obtained through direct perception. Mathematics was also challenging: is “2+2=4” a generalization from experience? What about the Pythagorean Theorem? The rationalists argued that knowledge of mathematics and ultimate causes could not be justified by experience alone, and they therefore represent a form of epistemological holism.
In contemporary scientific inquiry, questions of epistemological reductionism are asked about different levels of inquiry. In the social sciences, for example, there has been a long debate about how social theories are related to psychological theories. Durkheim explicitly denied that his explanations of social relationships could be understood in terms of individual choice. This form of holism was opposed by the “methodological individualists,” who tried to think about social phenomena as the outcome of patterns of individual actions.
In epistemological reductionism, then, issue is whether one sort of theory or intellectual domain can be fully explained by reference to another. Strong forms of epistemological reductionism hold that the higher level theory can be entirely constructed or justified by our knowledge of the lower level theories. In other words, a reductionist about the social might hold that once we knew everything about individual choices and motivations, we would be able to predict and explain the character of institutions. Similarly, epistemological reductionists about the mental would hold that all psychological experience can be understood in terms of neurological mechanisms.
Strong forms of epistemological reductionism hold that some higher-level domain can be fully understood (predicted, explained, justified) in terms specified by a lower level domain. Strong forms of epistemological holism hold that knowledge of the two domains is independent: knowledge of the lower level (e.g. neurological events or individual choices) tells us nothing about the higher level (e.g. mental or social phenomena). There are many varieties of weak holism too. A weak form of holism would deny the strong reductionist claim, but not go so far as the strong holist. On these kinds of view, knowledge of the lower level is relevant, but not exhaustive. Higher level theories would require concepts and methods of justification that were different from those used at the lower level, but knowledge of the lower level is important for a full explanation of higher level phenomena.
Many theories in the health sciences exhibit a commitment to moderate epistemological holism. The gate-control theory of pain, for example, relies on an understanding of neurological mechanisms to explain pain. But a person knows that she is in pain because of her experience, not because of her knowledge of neuroscience.
Other Forms of Reductionism
Two other forms of reductionism are ontological reductionism and practical reductionism. The motivation for ontological reduction is ontological economy: trying to show how some parts of the world are constructed from others. When nurses affirm the value of holism, they are often not denying either epistemic or ontological reductionism. Rather they are affirming the value of a complete and integrated approach to the patient. This is practical holism, and in the next post, we will discuss how it is different from epistemological and ontological holism.