Downward Causation: The Consciousness Revolution in Science By Roger Sperry

Editor's note: The following excerpt is taken from "Structure and Significance of the Consciousness Revolution", Roger Sperry's paper in The Journal of Mind and Behavior (Winter 1987, Volume 8, Number 1). Dr. Sperry is one of the world's most acclaimed neuroscientists, and in 1981 won a Nobel Prize in Physiology or Medicine for his work differentiating the functioning of the right and left halves of the brain. Sperry has also been concerned, for well over 20 years, with the philosophical dimensions of mind/brain research. His theory of "emergent interactionism", in which inner conscious awareness is explicitly recognized as a cause of behavior and a factor in evolution, represents a major challenge to reductionistic, physicalistic, philosophies which deny subjectivity a meaningful role in brain processes—or life. In this excerpt he explores the differences between these two views.

We have in science today two major conflicting doctrines of causal control, two conflicting scientific descriptions of the kinds of forces that govern ourselves and the world. The classic view reduces everything to physics and chemistry and ultimately to quantum mechanics or some even more elemental, unifying theory. Everything is supposed to be governed from below upward following the course of evolution. Science, in this traditional micro-determinist view, presents a value-devoid, strictly physically driven cosmos and conscious self, governed by the elemental forces of physics and chemistry, ultimately by quantum mechanics. By this long dominant physicalist-behaviorist paradigm there is no real freedom, dignity, purpose or intentionality. These are only aspects or epiphenomena of mind which in no way influence the course of physical events in the real world or in the brain.

According to the new mentalist view, by contrast, things are controlled not only from below upward by atomic and molecular action but also from above downward by mental, social, political and other macro properties. Primacy is given to the higher level controls rather than to the lowest. The higher, emergent, molar or macro phenomena and their properties throughout nature supersede the less evolved controls of the components. The concepts of physical reality and the kind of cosmology upheld by science in the two conflicting views thus differ vastly, particularly with respect to their psychological and humanistic implications....

The concept of downward control and how it works in emergent interaction is critical for the present claim that fundamental concepts of causation are at stake. The fact that downward, top-down, emergent, molar or macro causation continues to be contested, especially in the exact sciences, but also in philosophy, indicates that it either has not been adequately explained or that it fails to hold up under examination. Because it lies at the heart of our present thesis some further explanation is in order before proceeding.

Downward determinism... [was introduced in 1964] in terms of biological hierarchies.... Spelled Out more fully in the following year (in relation to consciousness and evolution—with direct implications for freewill, values, and the worldview of science), this emergent control concept was presented as a new solution to the mind-body problem. It was also described by Popper as a new view of evolution and a different view of the world. Perceived to lead to a compromise or middle way philosophic outlook that is neither dualism nor traditional materialism, it denied that the mental can exist apart from the functioning brain. At the same time it accepted the objective causal reality of mental states at their own level as subjectively experienced. The downward control aspect, later dubbed "downward causation", has also been referred to as "emergent causation", "holistic control" and "molar determinism" in opposition to the traditional microdeterminism of materialist doctrine.

Because the concept is critical for the idea of a more valid scientific paradigm and continues to be disputed, some further explanation is attempted in the following passage using simpler examples which will serve also to emphasize the universality of the principle. As such an illustration, consider a molecule in an airplane leaving Los Angeles for New York. Our molecule, say in the water tank or anywhere in the structure, may be jostled or held by its neighbors—but, these lower level actions are relatively trivial compared to the movement across the country. If one is plotting the space-time trajectory of the given molecule, those features governed from above by the higher properties of the plane as a whole make those governed at the lower molecular level insignificant by comparison.

The same principle applies throughout nature at all levels. The atoms and molecules of our biosphere, for example, are moved around, not so much by atomic and molecular forces as by the higher forces of the varied organisms and other entities in which they are embedded. The atomic, molecular and other micro forces are continuously active but at the same time they are enveloped, submerged, superseded, "hauled and pushed around" by, or 'supervened" by an infinite variety of other higher molar properties of the systems and entities in which the micro elements are embedded—without interfering with the physico-chemical activity of lower levels.

Reductionists claim that the entire flight of the plane from Los Angeles to New York can be accounted for in terms of the collective atomic and molecular activity, eventually quantum mechanics. The "macro" answer asserts there is no way that quantum mechanics can describe the multinested spatial features of the plane's structure which govern the flight as much as the molecular components per se. Similarly, the timing factors, as in its various motors, could not be accounted for by quantum mechanics. The plane will have radio, computer, and TV circuits. If one were to disconnect two elements in these circuits and reconnect them in reversed manner, the whole system would fail. The particular connections of the circuit plan cannot be determined from quantum mechanics; the laws for circuit design come from a higher level. In general, subatomic physics fails to give a full account of these higher organizational features.

The same applies to the circuit plan and function of the nervous system. If one were to plot the firing pattern for a given cortical neuron involved in cognitive function, the bursts of activity would, of course, be correlated with the local excitatory and inhibitory inputs to the given cell. At the same time, the timing of the neuron's firing, as well as that of its local input, would also be found to be determined predominantly by the train of mental events that happens to be in process. A change in mental programming brings corresponding major changes in the given neuron's activity pattern.

Most everyone agrees that neuronal events determine the cognitive events, but it is also true that the mental events, once they emerge, interact with other mental events at their own level and in the process also exert downward control to determine concomitantly the firing patterns of their neuronal constituents. The controls work both ways, upward and downward as well as sequentially. In "emergent interaction" or "emergent determinism" the mental events control neuronal activity at the same time that they are determined by them. The downward control view contends that the higher emergent forces and properties are more than the collective effect of the lower because critical novel space-time factors are not included in the laws governing the components.

It may be objected that examples of interlevel causation in which both levels are physical are no help to explain the mind-brain relation where one level is mental and thus by definition nonphysical. Our present thesis discounts such objections claiming the pertinent causal principles are the same. Brain processes have many unconscious as well as conscious emergent properties. Just because some emergent properties are subjective does not mean their basic interlevel causal control relationships are therefore different. Identity theory disposes of this issue semantically by calling the subjective properties physical properties.

In probing further the micro versus macro dispute it may help, at the risk of being repetitive, to focus on a simple familiar example, such as the downward control exerted by a molecule of water over its hydrogen and oxygen atoms. It usually is agreed that the laws defining the behavior of the atoms, particularly their course through time and space, become quite different after the atoms become joined together as a molecule. Although the atomic properties in the main are preserved, the atoms, once joined, are obliged to follow a new space-time course determined predominantly by the higher properties of the water molecule as a whole.

Many reductionists concur but argue that the new properties of the molecule are themselves determined entirely by those of the atoms and in fact can be completely predicted from the atomic properties. The macrodeterminist answer holds that predictability is not the issue here. Being able to predict the formation of novel emergent properties does not make the new properties go away or make them any less real, less novel or less important and powerful as causal determinants. The macrodeterminist can accept that the entire course of evolution is predictable, in principle, starting from subatomic properties, but this does not change the argument that evolution does occur, that new properties and control forces do emerge and that when they do, they exert downward control over their constituents which, as a result, are thereafter governed by new scientific laws.

The old reductionist claim that the properties of the molecule are nothing but the collective effects of the constituent atomic properties usually becomes qualified, these days, by the addition of some phrase to include the new organizational or spatio-temporal relations. With very simple entities, like the water molecule, the spacing and timing may be closely determined by the atomic properties themselves—but this does not hold for more complex entities, as in our airplane, for example, where the coherent configuration may be a product of anything from chaos to an inventor's insight. Again, however, to be able to describe how the formation of the new properties was determined does not provide scientific descriptions or laws for the new entities. The point is that the new emergent entity with its new spatio-temporal arrangement and resultant new properties, once it has come into existence, deserves to be treated and recognized in its own form for what it is— not solely as a collection of its elements in a special new space-time arrangement.

For an accurate, complete, scientific description of nature, the spacing and timing of all the multinested elements at all levels must be included. Science has laws for the behavior of the material, mass-energy elements but in general does not have laws for the complex multilevel space-time components. The space-time, or pattern factors, however, are automatically incorporated in the laws for the macrophenomena, as, for example, in classical mechanics. Properties manifest at subatomic levels tend to be bound up and controlled by properties at higher levels. If an uncertainty principle is operating at sub-atomic levels this does not necessarily imply that this uncertainty operates in the whole natural order at large, or characterizes the essence of reality.

It is frequently objected that if science has been wrong on this issue, how could it have been so eminently successful? It needs to be remembered in this connection that microdeterminism in itself is very valid. It is not contradicted by the acceptance of emergentism and downward control; neither is the value of the analytic, reductive methodology of science. It is only the exclusion of macrodeterminism that is claimed to be in error, and science has not excluded macrodeterminism in practice, only in its philosophy, theory and outlook. The microbiologist, for example, consistently relies on macrodeterminism and downward control in the treatment of molecular activity. It is in treating organisms, not molecules, that biology usually becomes reductionistic. The laws of classical mechanics are heavily macrodeterminist. In general, science has always depended on macrodeterminist principles though this has usually remained tacit and unrecognized....

Many…examples could be cited from a continuing series of ideologic, philosophic, and even theological contributions that have appeared since the sixties in which a new world outlook is upheld rejecting both traditional mechanistic approaches on the one hand and supernatural explanations on the other in favor of a midway holistic or emergentist position. The logical underpinnings of these varied proposals appear, in final analysis, to rest on a common basis similar to that of the new mentalist outlook in psychology. They all boil down to an acceptance, not of many or several, but of one major paradigm change, involving a core principle of causal determinism with wide application to rational explanation in general, not only in science but also in the humanities.