One of the most important contemporary statements of emergence in the philosophy of mind comes from no less illustrious a writer than the Nobel Prize-winning neuroscientist Roger Sperry. Sperry notes that many neuroscientists hold to the "materialist-behaviorist" principle according to which neural correlates of subjective experience exhibit the sort of causal efficacy which psychologists ordinarily attribute to genuine mental properties or substances. Indeed, the latter are held to not exist, a la the eliminative materialists, or, if they are held to exist, they are at least held to lack causal efficacy, as in the case of the epiphenomenalists.
Sperry, on the other hand, argues that mental properties are emergent and causal. For Sperry, basal material conditions produce "nesting brain hierarchies of high order, functionally derived, mental properties that interact by laws and principles different from, and not reducible to those of neurophysiology"(Sperry, 1980). He sees a reciprocal relationship between both upward and downward causation, rather than affirming merely upward causation like the materialist-behaviorist thinkers whom he criticizes. This is constituted as an "interlevel determination of the mental and neural action...accounted for on these terms without violating the principles of scientific explanation and without reducing the qualities of inner experience to those of physiology"(Sperry, 1980). Indeed, he believes this account is not only not a form of supernaturalistic dualism, but he believes it to be more scientifically defensible than such reductive physicalism.
In particular, he notes Karl Popper's "The Self and Its Brain - An Argument for Interactionism" in favor of the emerging popularity of an emergent-interactionist account of the mind-brain relation. Popper cites Sperry himself in support of his thesis. Sperry, however, did have some criticisms of Popper's appropriation of his resaerch.
For example, some have pegged Sperry as a dualist. Sperry takes exception to this and affirms that he is, in fact, a monist. As such, he denies that a conscious mind can ever exist apart from a functioning brain. Sperry may be anti-reductionist, but he is still a monist. Nonetheless, he dislikes the label "physicalist," presumably due to its association with reductionism, and sees himself more as a mentalist. It is a mentalism, however, that is monistic rather than dualistic. Although he rejects the label of physicalist due to a tendency to conflate physicalism with reductionism, he clearly teaches a form of non-reductive physicalism. According to his monism, mental properties can exert genuinely causal effects.
For Sperry, emergent mental properties exert causal effects over electro-physiological activity in the brain. They are different from this activity, exert control over it, and are not reducible to it. Indeed, this means that mental properties are able to exert causal effects upon brain matter. He notes that this position was quite unpopular among the prevailing materialist-behaviorist philosophy of his time, which had no need for references to consciousness or mental concepts, rejecting the very existence of such concepts as unscientific. He soon identified himself as a "mentalist," not in the traditional philosophical sense in which the existence or relevance of matter was denied, but in the sense that mechanistic accounts of the human brain typical of behaviorists were rejected.
Sperry, then, became a psychophysical interactionist. He notes his departure from earlier emergentists, such as C. Lloyd Morgan, whose emergentism was a kind of epiphenomenalism which ultimately rejected the capacity of the mental for downward causation. This was not traditional dualism, however, since the mind must still be understood in terms of the basal brain properties which generate it.
In the 1970s, Sperry's emergent interactionism, and views similar to it, became increasingly popular, and subjectivity was increasingly invoked as having causal efficacy and explanatory relevance in studies of the brain. While Sperry's teachings have parallels in the aforementioned work of Karl Popper, Sperry does not use an emergent account of the mind as an argument for the existence of free will. Instead, Sperry is a determinist. Sperry favors "an emergent, mentalist form [of determinism] that follows logically from my concept of mind as causal"(Sperry, 1980). Thus:
"In contrast to Popper, I hold that every time the elements of creation, whether atoms or concepts, are put together in thet same way under the same conditions, that the same new properties would emerge and that the emergent process is, therefore, causal and deterministic"(Sperry, 1980).
He notes that while an exhaustive account of the physiological constituents of the human person and its brain processes may allow us to faithfully predict the behavioral and mental course of the human mind with exact precision, on a purely hypothetical level, this is obviously impossible from a practical standpoint. In illustrating his distinctly emergent brand of determinism, Sperry uses
"the example of how a wheel rolling downhill carries its atoms and molecules through a course in time and space and to a fate determined by the overall system properties of the wheel as a whole and regardless of the inclination of the individual atoms and molecules. The atoms and molecules are caught up and overpowered by the higher properties of the whole. One can compare the rolling wheel to an ongoing brain process or a progressing train of thought in which the overall properties of the brain process, as a coherent organizational entity, determine the timing and spacing of the firing patterns within its neuronal infrastructure. The control works both ways; hence, mind-brain 'interaction'. The subsystem components determine collectively the properties of the whole at each level and these in turn determine the time/space course and other relational properties of the components. The organism and its component cells and organs is another familiar example. The principles are universal"(Sperry, 1980).
Another example he uses is that of the electronics of a television set and the relation of these electronic substrates to the images they produce on its screen. It is essential to understand the former in order to know how the television works, but we cannot explain the processes of the images on the screen in terms of them. This is because
"They involve a different order or level of interaction. Yet these higher order, supervening, program variables do control at each instant, and determine the space-time course of the electron flow patterns to the screen and throughout the set - just as a train of thought controls the patterns of impulse firing in the brain. The new shift to a new program or to a new channel can be compared to a shift in the brain to a new mental set focus of attention, or to a new thought seqeunce"(Sperry, 1980).
Sperry, Roger (1980). MIND-BRAIN INTERACTION: MENTALISM, YES; DUALISM, NONeuroscience Vol. 5, pp. 195 to 206, Pergamon Press Ltd 1980. Printed in Great Britain © IBRD 0306-4522/80/0201-0195S02.00/0 from http://people.uncw.edu/puente/sperry/sperrypapers/80s-90s/214-1980.pdf via http://www.rogersperry.info/