donald_d_hoffman's picture
Cognitive Scientist, UC, Irvine; Author, The Case Against Reality
Cognitive Scientist, UC, Irvine; Author, Visual Intelligence

We Will Soon Devise a Scientific Theory for the Perennial Mind-Body Problem

The enigmatic relation between conscious experiences and the physical world, commonly known as the mind-body problem, has frustrated philosophers at least since Plato, and now stonewalls scientists in their attempts to construct a rigorous theory. Yet I am optimistic that, despite millennia of prior failures, we will soon devise a scientific theory for this perennial problem.

Why such optimism? First, the mind-body problem is now recognized as a legitimate scientific problem. In 2005, the journal Science placed it second in a list of 125 open questions in science. During the twentieth century, a multi-decade detour into behaviorism sidelined scientific investigation of the mind-body problem. But three decades into the cognitive revolution, the problem was dusted off and again given serious scientific attention.

Second, scientists soon rediscovered that the problem is surprisingly hard. Neurophysics, real and artificial neural networks, classical and quantum algorithms, information and complexity—standard tools that prove powerful in the study of perception, cognition and intelligence—have yet to yield a single scientific theory of conscious experiences. We cannot, for instance, answer the basic question: Why must this particular pattern of neural activity or this functional property cause, or be, this particular conscious experience (say, the smell of garlic) instead of that other conscious experience (say, the smell of a truffle), or instead of no conscious experience at all? Precise predictions of this type, de rigueur for genuine scientific explanations, have yet to be fashioned, or even plausibly sketched, with the standard tools.

Third, although science is laudably conservative, yet when pushed to the wall by recalcitrant data and impotent theories, scientists have repeatedly proved willing to reexamine dearly held presuppositions and to revise or jettison the ineffectual in favor of unorthodox assumptions, provided that these assumptions permit the construction of explanatory theories that answer to data. Aristarchus, then Copernicus, countenanced a heliocentric solar system, Newton action at a distance, Einstein quanta of light and distortions of space-time, Bohr probability waves, superpositions and nonlocality. Theories of quantum gravity now posit eleven dimensions, vibrating membranes, and pixels of space and time. The initial response to such proposals is, invariably, widespread incredulity. But considerations of explanatory power and empirical adequacy, wherever they point, eventually win the day. Scientists revise their offending presuppositions, adjust psychologically as best they can to the new world view, and get on with the business of science in the new framework.

Evidence is mounting that the mind-body problem requires revision of deeply held presuppositions. The most compelling evidence to date is the large and growing set of proposals now on offer. All are nonstarters. They are, to quote Pauli, not even wrong. We have yet to see our first genuine scientific theory of the mind-body problem. This has prompted some to conclude that homo sapiens has been cheated by evolution and simply lacks the requisite concepts: Those concepts necessary for us to survive long enough to reproduce did not include those necessary to solve the mind-body problem. If so, there is little hope, at present, for swift progress.

I am optimistic, however, that the obstacle is not in our genes but in our presuppositions. Tinkering with presuppositions is more clearly within the purview of current technology than tinkering with our genes. Indeed, tinkering with one's presuppositions requires no technology, just a ruthless reconsideration of what one considers to be obviously true. Science has risen to the task before. It will rise again. But progress will be tortuous and the process psychologically wrenching. It is not easy, even in the light of compelling data and theories, to let go of what once seemed obviously true.

Here are some obvious truths that guide current attempts to solve the mind-body problem: Physical objects have causal powers. Neural activity can cause conscious experiences. The brain exists whether or not it is observed. So too does the moon, and all other physical objects. Consciousness is a relative latecomer in the evolution of the universe. Conscious sensory experiences resemble, or approximate, true properties of an independently existing physical world.

Will we soon be forced to relinquish some of these truths? Probably. If so, the current ontological predilections of science will require dramatic revision. Could science survive? Of course. The fundamental commitments of science are methodological, not ontological. What is essential is the process of constructing rigorous explanatory theories, testing them with careful experiments, and revising them in light of new data. Ontologies can come and go. One might endure sufficiently long that it is taken for a sine qua non of science. But it is not. An ontology breathed into life by the method of science can later be slain by that same method. Therein lies the novel power of science. And therein lies my optimism that science will soon succeed in fashioning its first theory of the mind-body problem. But at the feet of that theory will probably lie the slain carcass of an effete ontology.