Explanation and the “brain sciences”

In 1895 Sigmund Freud—then nearly 40 years old—had a finished draft of his Project for a Scientific Psychology. Not at all a “youthful” work, as it is often characterized, the Project would include significant elements of what was to become psychoanalytic theory and would prefigure the pivotal theory of repression advanced in his Studien über Hysterie written with Joseph Breuer and published the same year. As Breuer and Freud referred to the psychical mechanism of the unconscious in the published book, the guiding model for the work is a foundational neuronal mechanism hypothesized in the Project (Freud, 1895).

This should not be at all surprising, nor should the Project itself be judged as daring or inventive. Freud was trained in neurology under Ernst Brücke at the University of Vienna. Brücke had been research assistant to the famed Johannes Müller whose “law of specific nerve energies” explained the quality of sensations not in terms of the applied stimulus but in terms of the specific nerves thus activated. The experience is thus explained not as under stimulus-control but neurophysiological control. Brücke was also a colleague of both Hermann von Helmholtz and duBois-Reymond, forming with them a Physikalische Gesellschaft committed to the thesis that all biological processes are themselves grounded in physics and chemistry. Thus, Freud was absorbed into a medical community whose leaders had already devoted themselves to a rigorously physicalistic approach to health and disease.

Josef Breuer was first author of the Studien über Hysterie, Freud’s senior by 14 years, and, like Freud, fully trained and fully committed to physicalism and to what would now be called the “brain sciences.” Often neglected in accounts of Freud’s theoretical work, Breuer should be remembered as a prize student of Ewald Hering’s and as the first to establish the function of the vagus nerve in respiratory reflexes—the well-known Hering–Breuer reflex.

It is not beside the point to consider this reflex briefly. The question it answers is why the lungs do not become overextended during the inspiration of air. What Hering and Breuer showed is that a vagus-based mode of inhibition is triggered once lung tissue has been stretched to a threshold level. In other words, there are compensatory reflex mechanisms in place and triggered when the system is on the verge of being overextended. Clearly, in light of the specific training both Freud and Breuer received, in light of the prevailing conceptual orientation dominant in the medical science of the time and their fidelity to it, it is odd to find these lines in a more recent retrospective of Freud’s Project:

Although Freud was a trained neurologist, the neurology of his day was inadequate to the audacity of his vision of a scientific psychology …. It is only at present that we can even envision the possibility of achieving Freud’s dream …. Are we now in a position to realize Freud’s youthful “Project for a Scientific Psychology”? (Woody & Phillips, 1995, p. 123)

I believe the correct answer to this question is “No,” and that the same answer extends to contemporary projects based on what I take to be the same flawed rationale adopted by Freud. Reduced to a word—though as widely used these days, a less than precise word—the flawed rationale is that of reductive physicalism and the slogan arising from it, according to which physics is complete. Defenses of this rationale often proceed from criticisms of any and all alternatives. To the extent that such alternatives call for nonphysical modes of causation, the critic need only expose the (alleged) incoherence of a nonphysical cause of physical events.

A version of this is offered in David Papineau’s defense of physicalism. Referring to the putative “mental” causes proposed as additions to merely physical causality, he writes:

If there were such forces, they could be expected to display some manifestation of their presence. But detailed physiological investigation failed to uncover anything except familiar physical forces [i.e., forces that are not sui generis mental]. (Papineau, 2002, pp. 253–254)

Kindred versions of this notion are often expressed in terms of “causal closure,” according to which, in the words of Yaegwon Kim: “If we trace the causal ancestry of a physical event we need never go outside the physical domain” (1993, p. 280). Of course, on this understanding one might offer additional support to the alleged “closure” of causality by asserting that the causal ancestry of mental events never requires access to non-mental domains.

The very question of the “completeness” of physics expresses a transparently cognitive disposition which, itself, must be subsumed under the phenomenology of critical reflection. Stepping back from what amounts to a slogan, it is permissible to ask how “completeness” is to be understood. Surely uncertainty relations leave some room for less than complete accounts. Then, of course, there is that defiant obstacle to causal accounts: Just how is it that event-A “causes” event-B? Is time’s arrow unidirectional? What is the status of “space” over which causal influences are exerted? Clearly, this whole business of causality is a work in progress and, as such, does not serve well as the last word even on matters of physical events.

For argument’s sake, we may grant that such issues do not arise in the realm of billiard balls, inclined planes, ropes, and pulleys. We can grant that in some sense physics provides a causally closed explanation of physical events. For the aims and purposes of Psychology, however, the core question is whether the right understanding of mental life is provided by the same sort of explanation. Surely, it is not at all obvious that the alleged completeness of physics explains the classic revival in the architecture of the 18th century or, for that matter, Napoleon’s failed strategy in Belgium. For those not in the thrall of scientism, the sentence itself—Physics is complete—is so utterly beholden to considerations of a cognitive and even an aesthetic nature as to be nothing short of paradoxical (that the “completeness of physics” repost has been overplayed in defense of materialism is cogently argued in Crane, 1995).

There is little doubt but that Freud accepted the completeness of physics. The Project was devoted specifically to explaining unconscious processes in terms of neuronal events. To begin to see how misled Freud was in this regard, it is useful to consider the theoretically pivotal concept of repression. According to the theory, repression is an active process, utterly unlike passive forgetting. In a manner of speaking, the latter is also unconscious, for it would be uncommon for one consciously to strive to forget. But, whereas forgetting expresses little more than the limitations of memory, or factors that interfere with direct recall, repression presumably reaches something psychically significant.

Granting this much—and on the view that physics is complete—there are two plausible assumptions that might guide experimental investigations. First, if it is the case that two instances of a failure to recall are based on two distinctly different processes, those differences should be reflected in studies of their underlying physical mechanisms. Second, as these mechanisms are brain mechanisms, appropriate neurological study should yield an explanation accounting for both forgetting and repression. Exacting research on the synaptic chemistry of memory has become commonplace. Consider the work of the MIT team led by Susumu Tonegawa and more recent findings on the relative autonomy of mature synapses (Kelleher, Govindarajan, Jung, Kang, & Tonegawa, 2004). There have also been suggestive studies of neurophysiological events associated with voluntary attempts by human subjects to suppress information presented to them (Anderson et al., 2004).

Suppose it were possible at this point to integrate findings at the level of synaptic protein chemistry and findings at the level of the functional MRI in subjects intentionally suppressing information. For argument’s sake, assume that the integration is successful. Human subjects who intentionally suppress information are found to have neurons that fail to produce proteins associated with long-term and more recent memories. Consider now attempts to broaden the research to examine protein chemistry in instances of repression.

One begins to see the problem. Persons can be provided with techniques with which they voluntarily suppress information. Under such conditions, research surely can distinguish states in which information is suppressed, and states in which information is recalled. There is no reason in principle not to expect research even in the near future able to identify alterations in brain chemistry under such contrasting conditions.

However, on the psychoanalytic account of repression, the relevant state is not known to the experimental or clinical subject, or the investigator. Only through some form of psychoanalytic investigation might such material be brought to the surface of consciousness, and this only at a later date. What is finally understood as “repression” reaches events rooted in occurrences that may have taken place years, and even decades earlier. Of course, such an account is per force conjectural. It is plausible, if indeed it is ever plausible, only on the assumption that the psychoanalytic theory of repression is correct. In other words, in order to locate and differentiate brain mechanisms somehow responsible for repression as distinguished from mere forgetting, the theory of repression stands as a necessary presupposition. To state the case tersely, Freud’s Project—far from vindicating psychoanalytic theory—would require an uncritical acceptance of the theory as a precondition for testing it.

It is tempting to reflect further on psychoanalytic theory owing to the extraordinary influence it has had not only on practitioners but on the proverbial rider on the Clapham omnibus. As a therapeutic, its record is at best marginal, not quite on par with pastoral counseling. As a theory, its central tenets are so utterly elastic as to be rendered compatible with virtually any data gathered as tests of validity and reliability. Setting all this aside, there is an interesting kinship between the psychoanalytic mode of explanation and that now on offer from the brain sciences. Both move the sources of human experiences to domains inaccessible to the actors themselves. Both support the conclusion that significant motives, feelings, and judgments are based on processes beyond the direct control of the actor. In a word, both claim superiority over and the right to replace “Folk Psychology.”

The example drawn from the theory of repression is illustrative of the failed rationale in the entire explanatory apparatus of psychoanalytic theory. It is, alas, less a theory than a species of narrative that strives to supply a coherent and plausible account of just how Jack and Jill came to think, feel, and act as they do. It makes no more sense to ask if it is a true story than to ask if Captain Ahab was obsessed with a white whale. It makes just as much sense to ask if the fMRI is the right instrument for uncovering the causes of obsessions.

Writ large, just what is the problem? Philosophers have the disarming habit of classifying truly complex issues under misleadingly simple headings. If, as is widely believed, the major problem in philosophy of mind is the problem of consciousness, it is so, we learn, because of something rather innocently referred to as the explanatory gap. The first one to employ the phrase “explanatory gap” in the way that philosophers now wrestle with it was Joseph Levine in a 1983 article titled, “Materialism and Qualia: The Explanatory Gap” (Levine, 1983). If there is this gap, the question it raises is whether it is a measure of a work in progress, or whether it promises to remain just one of those eternally elusive facts of life, specifically facts of mental life.

From among candidate explanations, how should one choose the one that seems just right to fill such a gap? What criteria matter most in judging the aptness of an explanation? Approaches to the problem of explanation should begin with a serious consideration of just what calls for explanation. In this undertaking, the temptation to be avoided finds the choice of more tractable but unrealistic problems, well suited to a particular model of explanation, but one entirely misplaced when directed at what really matters. A kindred temptation is to require of explanations that they address events the character of which is determined by the mode of inquiry rather than by the conditions under which such events typically take place. Once a memory drum is used to present experimental participants with pairs of words, it is inevitable that memory will prove to be an associative process strengthened by repetition. Once evolutionary theory is taken as explaining complex patterns of human behavior, even saintly actions will be judged as self-regarding, with infidelity now understood in terms of the replacement index!

How do we explain a complex event such as sending astronauts to the moon? How is the success of that sort of mission best explained? Surely one explanation is that the scientific laws on which the entire project was based are correct or true in that, if they weren’t, the mission would have failed. This is the familiar approach based on the notion of an inference to the best explanation. If one were to ask why the basic laws of physics at the macro-level are judged to be correct, one reasonable answer would be, “Because the mission to the moon succeeded and was firmly based on the laws of physics.”

Now consider the fairly mundane setting in which people decide to share a meal. It is the very descriptive terms that supply the explanation: FRIENDS, SHARING, MEAL. These are irreducible terms, not in the sense that there might not be some sort of physiological correlate for each, but in the sense that no such correlates can be sought except on the supposition that there are states of friendship, meals, and sharing.

Here, then, is one basis on which to judge the quality of explanations: all other considerations being equal, the better of two explanations satisfies two criteria. First, it is the one that is applicable over a wider range of instances than alternative explanations. Second, it is the more foundational explanation. Regarding the latter, Explanation-A is more foundational than Explanation-B when Explanation-A accounts for the adequacy of Explanation-B, but not vice versa.

In the matter of the explanatory “gap,” the difficulties appear to be based on a search for the wrong kind of explanation; a search for some sort of causal relationship between activity in the brain and the actual and highly individuated lives of real persons. The difficulties cut across fields of scientific and scholarly concern, for there is a lingering positivism that would be dismissive of so-called “Folk Psychology” and comparably dismissive of humanistic approaches to the human condition.

The very term “Folk Psychology” lends itself to so many and various construals as to require clarification each time it is used. I would have it understood as a blanket-term for what Thomas Reid referred to as principles of common sense. In Sec. 4 of the Introduction to his Inquiry, he identifies the chief source of popular skepticism toward philosophy:

The adherents of this philosophy, led by a natural prejudice in her favour, have tried to extend her jurisdiction beyond its proper limits by setting her up as a judge of the dictates of common sense. But these dictates refuse to be judged in this way; they despise the trial of reasoning, and disown its authority; they don’t look to reason for help or fear its attacks. In this unequal contest between common sense and philosophy the latter will always come off with both dishonour and loss; nor can she ever prosper until this rivalry is dropped. … Philosophy’s only root is the principles of common sense; it grows out of them, and draws its nourishment from them; when it is cut off from this root its honours wither, its sap is dried up, it dies and rots. (Reid, 1764)

A Reidian principle of common sense is not a matter of opinion or the subject of dispute, but a principle that one is under an obligation to take for granted in all the ordinary affairs of life. That the world of perceptual experience actually exists can only be doubted by the lunatic or one temporarily suffering from what Reid would label “metaphysical lunacy.” Thus,

If Nature intended to deceive me, and impose upon me false appearances, and I by my great cunning and profound logic, have discovered the imposture; prudence would dictate … not to call her an impostor to her face, lest she should be even with me in another way. For what do I gain by resenting this injury? You ought at least not believe what she says. This indeed seems reasonable, if she intends to impose upon me. But what is the consequence? I resolve not to believe my senses. I break my nose against a post that comes in my way. (Reid, 1764, p. 544). ¹

The point of course, is that certain common notions or precepts are assumed even by the skeptic. To mount an argument against the law of contradiction is to have adopted the logical apparatus of argument itself. “Folk Psychology,” understood in this way, takes for granted just those linguistic, social, and cognitive resources required if creatures are not only to share a form of life, but to engage in scientific, artistic, and civic undertakings all predicated on necessary assumptions. It is in this respect that the precepts of Folk Psychology are more foundational than those on which reductive strategies are based.

An illustration will make this clearer. When research avails itself of physiological measures, MRIs, etc., and moves toward a causal account of some state or event, there is the foundational assumption that highly regular associations are not accidental. That is, we cognize certain regularities as “causal,” but not because science somehow has shown this to be the case. The mode of cognition is as evident in preliterate societies as it is at MIT. Absent this supposition, science itself could never have arisen and daily life would be a wreckage. Note that science is parasitic on such precepts and cannot claim pride of place above them.

It is now a little more than a half-century since William Dray (1957) wrote his then influential Laws and Explanation in History. He was a clear and convincing spokesman for the Verstehen school of historical scholarship, sharing with R. G. Collingwood the conviction that, to the extent that history arises from the actions of persons, the understanding of history requires an inquiry into the beliefs, aspirations, and motives of the actual participants. Recognized here is the distinction between Erklären and Verstehen (explanation and understanding; for an instructive recent discussion, see Feest, 2009). Thus, Collingwood’s own expressed admiration for Freud and psychoanalytic theory. But Collingwood would have had little admiration for the Freud of the Project who might prefer some neurological account of what is most fully understood in terms that are most fully humanistic.

It is common to contrast Verstehen and scientific modes of explanation in terms of subjectivity vs. objectivity. Of course, science itself aspires to just that causal closure, just that completeness that constitutes an ever fuller and deeper understanding. The global perspectives with which the names of Newton, Galileo, and Einstein are associated stand as holistic conceptualizations of the physical world. That the actual items and forces at work in these grand theories are objectively observed and measured does not alter the global character of the aims and the achievements of the physical sciences.

At the level of human personal, social, and civic life, there are facts of nearly comparable regularity, comparably fit for objective appraisal. These are the facts of Folk Psychology which stand as the irreducible features of ontological reality. There are good reasons for seeking associations between that reality and various states and events in the brain. But these reasons do not promise either causal explanations or that fuller understanding generative of holistic comprehension of the defining nature of human nature.

The foundational science, if there is one, must be Folk Psychology, and this even for the “brain sciences,” to the extent that the latter claim to be of wider consequence than, say, the “kidney sciences” or the “spleen sciences.” The claim that the “brain sciences” make for themselves is that they reach what is most defining and momentous in actual lived life. What they reach for, therefore, is a Folk Psychology, inevitably less prone to “gaps” than would-be substitutes.

This is not the occasion for yet another consideration of the mind–brain issue, but there is an aspect of that issue that bears upon the nature and the limitations of attempts to explain complex phenomena by way of the operation of seemingly basic laws. An example is offered to challenge complacency. There is recognition of the misapplication of the conservation laws in attempts to defend versions of physicalism against dualistic or mentalistic accounts. However, there is less inclination to address the nearly tautologous character of the basic law itself. Among the first to discuss this in some detail was Henri Poincaré (1905). Noting that the most general statement of the law is given as: T + U + Q = Constant (Where T is kinetic energy, U the potential energy of position, and Q the internal molecular energy), under the thermal, chemical, or electrical form, Poincaré noted that the three terms were not sufficiently distinct. Electrostatic energy depends on the charge of the bodies as well as their position when in motion. Their energies will depend upon their relative states, positions, and velocities. He concludes:

We therefore no longer have any means of making the separation of the terms which should make part of T, of U, and of Q, and of separating the three parts of energy …. Among the functions which remain constant, there is none which can be put rigorously under this particular form; hence, how to choose among them the one which should be called energy? We no longer have anything to guide us in our choice. There only remains for us one enunciation of the principle of the conservation of energy: There is something which remains constant. Under this form it is in its turn out of the reach of experiment and reduces to a sort of tautology. (Poincaré, 1905, p. 93)

It is surely not my aim to challenge the most basic laws of physics; competent physicists do this all the time. Rather, I draw attention to the value of abandoning simplistic reductionistic strategies and taking ever more seriously the busy world of actual persons, striving to realize in fact what is desired in thought and urged upon them by their stronger sentiments (Robinson, 2008). Taking this world seriously requires giving full benefit of doubt to Folk Psychology rather than the conventions of academic disciplines oddly regarded as having greater authenticity or validity. Just in case the conservation laws somehow outlawed all that is “mental,” we would have yet another reason for rejecting the proposition that physics is complete.

That seriousness is in short supply finds expression in contemporary disputes between “cognitivists” and “noncognitivists.” Philosophers and cognitive neuroscientists form an enlarged circle of specialists arguing about the relative power or place to be occupied by “the emotions” and “reason” in “determining” behaviour. The fairly broad division between “cognitivists” and “non-cognitivists” is not on the question of the ontological distinctness of reasons and emotions, but on which has ultimate causal or trumping power, which is the better predictor. However, what actual life makes clear is that those of our undertakings which we regard as worthy of philosophical or psychological interest will not admit of such partitioning or even of such a distinct ontology. Having a good reason to act is, among other considerations, to be disposed in ways dependent on confidence, conviction, satisfaction, highly subjective assessments of costs and benefits, allegiance to moral precepts, estimations based on “all-things-considered,” hopefulness—factors scarcely touched by textbook notions of “reasons” and “emotions.” To think of these terms as referring to partitionable features of mental life is to think that one can pull out of the cup what is hot, then what is sweet, then what is liquid and then what is brown—all the while accounting for “hot chocolate.”

It is of some value in intellectual pursuits to aim high but be modest in one’s promises. So I close with some observations handed down by William James over a century ago, toward the end of the 1892 edition of his Psychology. Here was his appraisal of the state of affairs in 1892, perhaps not misplaced when directed toward the brain sciences of today:

A string of raw facts: a little gossip and wrangle about opinions; a little classification and generalization on the mere descriptive level; a strong prejudice that we have states of mind, and that our brain conditions them: but not a single law in the sense in which physics shows us laws, not a single proposition from which any consequence can be causally deduced. … This is no science, it is only the hope of a science. (James, 1892, pp. 467–468)

This is no cause for skepticism, less for foreclosing the prospects of an ever more developed and systematic account of what presents itself as the human condition. Rather, it is important to keep clear as to what it is about that condition that renders it at once compelling and elusive; also keeping in mind Reid’s (1764) caution, that, “Conjectures and theories are the creatures of men” (p. 400), unlike the creatures of nature.