Murphy’s Non-Reductive Physicalism

Christian philosopher Nancey Murphy, reflecting increasing Christian scholarship calling for acceptance of physicalism, argues that the theological workability of physicalism depends on the success of an argument against reductionism. She takes Non-Reductive Physicalism, a common term in philosophy of mind, to “signal opposition to anthropological dualisms of body and either mind or soul, as well as to physicalist accounts that reduce humans to nothing but complex animals.”

She sets herself the task of showing that “non-reductive physicalism is philosophically defensible, compatible with mainstream cognitive neuroscience, and is also acceptable biblically and theologically”—a task made more difficult because she must be able to explain “how Christians for centuries could have been wrong in believing dualism to be biblical teaching” (Murphy, 2017, 2018).

Biblical Translation and Dualism

To Murphy, part of the answer lies in translation. She focuses on the Septuagint, a Greek translation of the Hebrew scriptures that dates from around 250 BC. This text translated Hebrew terminology into Greek, and “it then contained terms that, in the minds of Christians influenced by Greek philosophy, referred to constituent parts of humans. Later Christians have obligingly read and translated them in this way.” A key instance, she says, is “the Hebrew word nephesh, which was translated as psyche in the Septuagint and later into English as ‘soul’ … In most cases the Hebrew or Greek term is taken simply to be a way of referring to the whole living person” (Murphy, 2018).

Murphy is impressed by how many capacities or faculties of the soul, as attributed by Thomas Aquinas, are now well explained by cognitive science and neurobiology. She is moved by “localization studies—that is, research indicating not only that the brain is involved in specific mental operations, but that very specific regions are.”

That gives her the physicalism—the easy part, I'd say. What about the non-reductive—the hard part?

Downward Causation and Systems Theory

An obvious answer to the problem of neurobiological reductionism, Murphy says, would be the presence and power of downward causation or whole-part causation. That is, if causal reductionism is the thesis that all causation is from part to whole, then the complementary alternative causation would be from whole to part.

If we describe a more complex system, such as an organism, as a higher-level system than the simple sum of its biological parts, then causal reductionism is bottom-up causation, and the alternative, causal anti-reductionism, or causal non-reductionism, is top-down or downward causation (Murphy, 2017).

To support Non-reductive Physicalism by undermining reductionist determinism, Murphy recruits contemporary concepts in systems theory, such as chaos theory, non-linear dynamics, complex adaptive systems, systems probabilities, and systems biology. Thus, Murphy posits, an understanding of downward causation in complex systems allows for the defeat of neurobiological reductionism.

Finally, Murphy muses that “non-reductive physicalism, while it is the term most often used in philosophy, is perhaps not the best for purposes of Christian anthropology, because, at least by connotation, it places disproportionate stress on the aspect of our physicality.” She quotes theologian Veli-Matti Kärkkäinen in proposing a replacement: “multi-aspect monism” (Murphy, 2018).