The story so far…
In Varieites of Reductionism: Three Varieties (Part 1), I discussed the problem of reductionism as it appears in nursing and described “epistemological reductionism.” This involves the relationship of one theory to another. There are two other kinds relevant to the issue of reductionism: ontological reductionism and practical reductionism. This post will articulate ontological reductionism.
Ontological reductionism and holism
Questions of ontology concern what exists and what kinds of things there are. Whether God exists, whether the number 2 exists, and whether cats have minds like ours are ontological questions. Questions of ontological reductionism ask whether one (purported) kind of thing can be identified with another. Thus, to say that there are no minds or spirits, only brains, is to take a reductionist position.
Note the difference between ontological and epistemological reductionism. In epistemological reductionism, the question about minds and brains is whether our knowledge of minds (and how they work) could be reduced to knowledge of brains (and how they work). The ontological question is whether there are two kinds of things (minds and brains) or just one (brains). The denial of ontological reductionism about the mind would hold that minds exist independently of brains.
Ontological holisms and reductionisms come in weak and strong forms. Strong holism contends that the two domains exist independently. Those who hold that the mind (or spirit) is a non-material entity which can survive the death of the body affirm a strong form of holism about the mind. Those who affirm that only brains exist affirm a strong form of reductionism.
Pain and weak holism
Middle positions are possible, and the Gate Control Theory of Pain provides an interesting example. The Gate Control Theory holds that pain signals travel along two kinds of neural circuit. One runs directly from the injured site to the motivational parts of the brain. The other goes through the higher processing, cognitive parts of the brain. The latter forms a “gate” which can block or modulate pain sensations. Is this a form of ontological reductionism? It seems so, insofar as pain is identified with neurological circuits. Notice, however, that the feeling of pain is not eliminated or explained away. It would be odd to be skeptical about the existence of the feeling of pain in a way that it is not odd to be skeptical about the existence of, say, souls.
The Gate Control Theory assumes that people feel more or less pain, depending on their emotional or cognitive state. Both the feeling of pain and the neurological states are assumed to exist. Hence, it is not strongly reductionist, since it does not deny that pains exist. Nor is it strongly holist, since the feeling of pain is said to depend on neural state; without neurological events, there would be no pain. The Gate Control Theory thus illustrates a weak form of ontological holism.
The ontological commitments of the Gate Control Theory are an intriguing example of the kind of conceptual change that comes about through scientific research. We come to understand our feelings of pain as complicated neural events. This is not as strange as it sounds at first. We understand hot and cold as the mean kinetic energy of molecules, and hot and cold are, in the first instance, feelings. There are not two things—heat and mean kinetic energy—there is but one, mean kinetic energy. The conceptual change instituted by theories like the kinetic theory of heat or the Gate Control Theory of pain are changes where two distinct concepts are unified.