Introduction

To develop a vocabulary with which to interrelate neuroscience, philosophy and psychology, I summarize three classes of theories relating mind and brain.  These complementary classes are materialist/empiricist, idealist/intellectualist, and existentialist/enactionist.  I describe examples for each class of its origins, successes and major problems. I emphasize the concepts of "meaning" and “intentionality”, because the main problem that each class of theories faces is best understood through its conception and treatment of meaning. I develop the proposition that ‘Animals’ create and grasp meaning through intentional actions in social contexts to the extent that they can establish the contexts.

Materialist

In materialist/empiricist views minds are flows of matter and energy that carry information.  Among ancient Greeks humors were the basic elements of which the world was made. Blood, phlegm, yellow bile, and black bile, were conceived as combinations of air, earth, fire, and water.  These components gave the material basis for the function of the body; health and disease depended on their balance, and perceived imbalances prescribed treatment.  For example,  excess water and insufficient air caused congestion; treatment was bleeding to restore balance, demonstrating cause and effect. Modern chemists modified this alphabet of elements by replacing humors with atoms and combinations into neurochemicals and genes that are conceived to control behaviors of brains and bodies. Diseases are caused by chemical and genetic imbalances that indicate treatments.

These theories have striking successes. Examples are Pavlovian psychology and behaviorism, in which all behavior consists of hierarchies of reflexes. Accordingly pain is treated by cutting pathways or blocking synapses with analgesics to close the “pain gate”. Chemicals serve to control behavior, mood, and emotional state. More problematic are proposals that undesirable behaviors such as violence, obsession, or hoarding might be treated by replacing specific genes.

The intractable problem for this approach is the nature of qualia, the subjective experiences that accompany neural activity. Chronic pain is very difficult to treat in the confines of materialist theories, and gene therapy for psychiatric disorders is only a dream. John Searle raised this problem with his question of how the meaningless firing of neurons can cause qualia, such as pain.

Philosophers often view meaning in this context as the awareness of feelings and emotions that are add-ons to stimuli and responses. Neurobiologists ask how the limbic system can contribute feeling to the neural activity that is generated in the cognitive hemispheres of the cerebral cortex, and how emotions can be attached to the motions controlled by the basal ganglia and cerebellum. The lack of a central place for emotion poses a great obstacle for a materialist foundation for psychiatry. 

Idealist

In the idealist or intellectualist views minds are collections of representations and symbols.  These views also originated in ancient Greece.  In the Platonic world of ideas there was a fixed set of ideal patterns that were imperfectly realized in the humors of the material world. Use of intellect was necessary to comprehend these ideal forms by processing raw sense data.  Plato characterized his approach to perception as passive in using the metaphor of the cave, in which light from outside cast shadows, the forms of which we now describe as information. Descartes mathematized this view in explaining brain function through the primacy of thought. Kant elaborated it into innate categories of mind, and concluded that all that we can know about the real world is filtered through our senses, which distort our apprehension of the world and prevent us from knowing it as it actually is.

This conception is widespread today, as for example in Noam Chomsky's linguistics inferring the existence of deep structure that is wired into brains. The neurobiology is not his concern; he postulates simply that there is innate connectivity common to all languages, the details of which are realized diversely in different societies and cultures from instruction by parents.   In my field the theory takes the form of neural networks. McCulloch, a neurobiologist, and Pitts, a logician, conceived neurons operating as binary switches doing Boolean algebra. The action potential is regarded no longer as an energy wave but as a binary digit of information — on-off, yes-no, one-zero — that carries information for processing according to rules deduced by neurobiologists.

This model was an inspiration for John Von Neumann to invent programmable digital computers. Information flowing from sources to sinks fills an ecological niche by replacing energy and matter as the vector for the flow of ideas. Crucial is the divorce of meaning from information, explicitly in Shannon-Weaver information theory.  Engineers are unconcerned about contents of telephone messages, only about their bandwidth and the number of bits required to transmit them.  The degree to which uncertainty is reduced gives meaning to the information.

This approach has the “hard problem” of David Chalmers, in which the attempt to realize artificial intelligence as an alternative to brains has raised the question: What is the nature of consciousness?  Cognitivists debate the “mystery of consciousness” as Searle calls it: how it is experienced, how it is caused by brains, if at all, and how it causes changes in behavior, not only of the firing in networks of neurons, but of the movements of the body. In its aspectual dualist form, this approach led Whitehead to “pan-experientialism”, by which there are no particles, only events; each particle hasa material aspect and an experiential aspect. Consciousness precedes intent and is conceived as the agent of intention.

The unsolved problem for the cognitive scientists is that in minds, being collections of representations, tokens, or symbols, meaning is defined as the relationship among symbols.  This is circular, because when one wants the meaning of a word, one looks for it in the dictionary, which gives more words.  Reference to the real world is not defined within or by a computer or a cognitivist brain. Stevan Harnad calls the problem of how to attach meaning to representations the “symbol grounding” problem.

Computational neurobiologists typically suppose that representations are embodied in the firings of neurons, each action potential symbolizing a feature, object or person like a grandmother; that these symbols are operated upon in the cortex according to neurobiological rules; and that the output is passed through the amygdaloid nucleus, where a meaning or an emotion is attached before the message is sent into the motor system. The symbol grounding problem is unsolved in neurobiology and artificial intelligence and is perhaps, along with the “hard problem”, unsolvable.

Existential

I have called the third class of views  “existential” in the terminology of Maurice Merleau-Ponty.  In his view mind is the structure of behavior.  The mind creates behavior and behavior creates mind.  This approach has multiple origins, first among them being Aristotle, who championed a view of perception as active in contrast to the Platonic view of passive intake of forms (information). Aristotelian perception required action — probing, cutting, burning, etc. Chief among his successors was St. Thomas Aquinas, who proposed that each person is a unified being using the body to probe the world. Such action expressed 'intent', from the Latin word 'intendere', which meant 'stretching forth' and shaping the self from the consequences of the action by assimilation (“adequatio”) followed by accommodation. He made no use of representation or consciousness; those are modern ideas. It is important to recognize that the Thomist interpretation of “intention” differs markedly from that of Anglo-American analytic philosophers, who follow Brentano in re-defining intention as the “aboutness” of explicit representations – a belief or thought is “about” something in the world.

The idea of the importance of action for understanding was developed in great detail by Merleau-Ponty, relying on medical literature from World War I, and by Jean Piaget and inter alia the school of pragmatism. A focus for Merleau-Ponty was the dissociation that brain injury revealed between the abilities to grasp and to point, by which he developed his concept of “the tendency toward a maximum grip”. This was also a concern for Piaget in his somato-motor phase preceding acquisition of higher order cognitive skills.  These different abilities appear at different stages of development. Children are born with the grasp reflex; their ability to manipulate objects appears in their first few months; the ability to point follows several months later. The remarkable feature of pointing is that this is a social action; the child points with the intent of communicating a target of interest primarily to its mother. The infant looks to its mother to see if she is looking where it is pointing. Grasping merely orients the body to an object in the outside world intentionally without necessary relation to another intentional being.  These operations are deep in brain organization. In the existential views meanings exist in social relations that are established by intentional action.

A related but differing view was developed by Gestalt psychologists, principally Wolfgang Köhler and Kurt Koffka, dealing not with brains but with fields of force that mediated between objects and egos.  One of the critical differences between the existential view and the Gestaltist view is the passive role of the perceiver, the ego, for Gestaltists. For example, Gibson (1979) conceived of information contained in an object in the form of an affordance, which was what an observer could do with it. “The object offers what it does because it is what it is (p. 139)." Meaning was carried by the information from the object as it flowed through the senses into the nervous system, where it was extracted by resonances that caused appropriate choices. Despite its emphases on action and reciprocity, Gestaltism is idealist and ultimately passive. Affordance does not constitute expectancy.

The existential views have been marginalized largely by their central problem: what causes intentional action?   According to both the materialist and intellectualist views, actions are determined by stimuli.  A laboratory rat is trained to sit inert until a stimulus comes, and then to do something.  Its behavior is stimulus-dependent.  A computer terminal waits for keystrokes before computing.  Wild animals and people aren't like that.  They continually engage the environment, reaching into it purposively. How do those endogenous actions arise?  How do neurons cause intentional actions that don't require stimuli to initiate them? For the materialist, intent implies teleology, which is inadmissible; for the cognitivist, intent implies aboutness, which is opaque; for the enactionist, intent is a mystery. For this neurobiologist intent is the doorway into neurodynamics. Brains are self-organizing systems that are future-oriented. The biological role of brains is to construct expectations of future states and schemata of actions by which those future states may be brought about and evaluated. What causes the expectations? 

Causality

We have a choice among meanings for the verb to "cause": (i) to make, move and modulate (an agency in linear causality); (ii) to explain, rationalize and blame (cognition in circular causality without agency but with top-down-bottom-up interaction); or (iii) to flow in parallel as a meaningful experience or by-product (Humean invariant relation). The most vexing problem is “agency”, leading to a variety of synonyms for causes: dispositions (Aquinas), regularities (Hume), tendencies (J S Mill), propensities (Popper), capacities (Cartwright), explanations (Donaldson), risk factors (statisticians), etc., in order to distinguish them from mere correlations and coincidences.

It is easy to conceive of how a reflex response is caused by a conditioned stimulus, but it is not easy to explain the causes of exploratory behavior.  Some psychologists say that a rat has a curiosity drive or a motivation for novelty that provides the cause, but these are only words. “Intent” is what the animal did or will do; “motive” is the reason we infer from what we observe and experience by introspection.  Brains have masses of interconnected neurons that generate the evolving patterns of behavior we observe as sequences of ordered, intelligible states. We perceive the behavior as goal-directed.  This animal is looking for something.  That animal is running away from something.  So we call the actions intentional, what neurologists call “voluntary” by invoking consciousness. Materialists assert that brains cause behavior without explaining intent; idealists claim that consciousness causes behavior without explaining consciousness; Merleau-Ponty opposed both views for what he called their “linear causality”. 

Linear causality is universal determinism in causal chains such as, A causes B causes C.  A stimulus excites sensory receptors; they excite the sensory cortex; that cortex transmits to the motor cortex; that activates motor neurons; muscles contract.  That is a sequence of linear events; at the core of cognitivist, computationalist, and materialist is linear causality.   Instead, Merleau-Ponty introduced circular causality.  Every action and every sensation is both a cause and an effect in what he called the “intentional arc”. It could not be reduced to linear causation but rather was inherently circular.  Consciousness was tertiary, a judgmental act late in this action-perception cycle, and certainly not the ego-driver of action.

This is the deep problem for existential theories: What is the origin of the structure in behavior, which is, according to Merleau-Ponty, mind? In these approaches meaning is created by the interactions of intentional beings with each other through the world. It exists in the engagements, not merely or only in the brains of the participants. It is ontologically in the world and is epistemologically grasped through introspection by inferences from observing goal-directed actions of others’ and one’s own. Recent advances in brain imaging have made it possible to observe the brain activity patterns of humans and other nonhuman animals who are engaged in intentional behaviors by which meaning is created.

Neurodynamics

Concomitant advances in the engineering and physical sciences in nonlinear dynamics have major import for solving the mind-brain problem, as it is understood through existential theories. My starting point is the Thomist postulate of the self as an entity that distinguishes itself from all aspects of the world outside itself. The self according to Tomaso has unity and integrity of action that precludes mutual interpenetration with the environment.  A modern analogy would be the immunological self that disallows exchanges among bodies of foreign constructions such as organ transplants and requires that all foodstuffs be reduced to simple molecules before absorption in the gut. Comparably, all sensory input is disintegrated into the action potentials of individual sensory receptors, leaving the spatiotemporal structures of stimuli behind in the world.

Brains self-organize their internal states to create assimilations of those spatiotemporal structures. More importantly, survival requires predictions of future states in the search for fuel, shelter, and companionship. Images of future states emerge from memories of past states and prior actions that succeeded or failed to achieve those pleasurable and avoiding those painful. An important consequence now verified by brain imaging is that, during perception, brains create expectations about the world in the form of landscapes of chaotic attractors, each corresponding to a class of stimuli. Each attractor is surrounded by a basin of attraction. Brains command actions to test their expectations by importing information through the senses in the form of stimuli. They use a stimulus to select a basin of attraction and update it in the process of assimilation. Convergence to the attractor deletes extraneous information in the stimulus by the process of abstraction. The neural activity pattern configured by the attractor gives the class to which the stimulus belongs in the process of generalization. The residual information serves to modify the attractor in the process of accommodation. Thus brains do not “process information” by storage, retrieval, and pattern matching. They use it for selectivity and then discard it.

The unity of action is not just momentary but spans the whole life of the self by creating knowledge, storing it by synaptic modification, and continually up-dating it with each new sensory impact.  As an example, an individual H.M. lost this capacity through a surgical operation intended for relief of epilepsy: removal bilaterally of large parts of his temporal lobes, including the hippocampus.  H.M. retains most experience from before the operation but cannot add anything new.  He lives eternally in the present.  He has lost the ability to construct his life story. Another example of the property of wholeness is revealed in the field of surgery, where by long tradition healing is described as by first or second intention.  First intention is formation of a clean scar; second intention is by infection with scar formation.  Healing expresses the biology of intention in re-establishing the integrity of the body after injury. The concept can also apply to the healing of psychic wounds of the self.

It is critical for my view and my interpretation of Merleau-Ponty that intention does not require consciousness and most often proceeds without it. This poses a difficulty for phenomenologists, whose ‘raw materials’ have the form of qualia, and whose ‘tools’ are provided by awareness through the languages of literature, sport, art and music. My reliance on neurodynamics enables me to conceive how self-organizing brain operations can explain processes described by Merleau-Ponty of humans learning new skills through language and logic, with reversion to smooth, thought-free execution after sufficient practice.

I conceive the emergence and execution of an intentional act as follows. A self-organized global pattern of synchronized neural activity emerges, linking by interactions masses of neurons in various parts of the forebrain that generate an expectation of a future state. This dynamical structure evolves into schemata of motor commands in specific modules that are delivered to the motor systems, with preafference copies sent to the sensory systems. There they guide the construction of expectations of the changes in sensory inputs that the forthcoming actions will entail. Feedback through the cerebellum confirms that the motor commands will soon be executed, and the proprioceptive sensors in joints and muscles feed back confirmation that the intended actions are taking place. This feedback on preparing and executing an action comes later to awareness in the form of a “cause”.

The sensory consequences of the action enter chains of neurons and ascend to cortical modules, whence still later they are assembled in the limbic system and disseminated through the forebrain. This closes the intentional arc by setting the stage for the next frame in a cinematographic process (Freeman, 2005). The up-date comes to awareness in the form of an “effect”. The cause-effect relation of these frames is linear, and the sequence is invariant. We act; we perceive. That is the essence of cause-effect, which is the foundation of all knowledge and social organization. All we can know is what we can predict, and what the results of our tests are. Consciousness is a late judgmental process, not an agency.

Conclusion

David Hume with legendary unassailability challenged the notion that causality is anything more than a feeling of certainty based on constancy of contiguity and temporal order. Elsewhere I have marshaled my own evidence that an awareness of cause is the quale that accompanies some cognitive constructs (Freeman, 1999). My aim here is to offer the explanation that people search for the causes of things because that is the way their brains work. As Hilary Putnam (1990) wrote: “Perhaps the notion of causality is so primitive that the very notion of observation presupposes it? “(p. 75) Why do some philosophers insist on asking how consciousness causes an object like a brain or a collection of neurons to move the body?  This is like asking, what causes the sun to move across the sky? Animists conceived a chariot with horses. Newton created a larger framework in which the agency was the pull of gravity. Einstein created a still larger explanatory framework, in which a calculus of relations between matter and observer replaced agency.

In my view we can create a new framework for causal cognition by combining nonlinear neurodynamics with Thomist intentionality, within which causality can be redefined. I believe that the sense of causation is an ethical necessity for assignment of responsibility and for defending the belief in one’s own power to make choices. We educate children and train animals by nourishing their feelings of guilt, in order that they perceive their actions as causes, so that we and they can control them. But the assignments of causation to objects like neurons, brains, and billiard balls, or to concepts like consciousness and related unobservables, appear to me as category errors. I propose this conclusion as a challenge in understanding causal cognition and its larger role in epistemology.

Acknowledgment

This essay is condensed from my notes for a course on “Intentionality in Philosophy, Neurobiology and Cognitive Science” given in the 1990s by myself and Hubert Dreyfus, Professor of Philosophy, University of California at Berkeley.

References

Dreyfus HL (2002) Intelligence without representation — Merleau-Ponty’s critique of mental representation. Phenomenology and the Cognitive Sciences 1: 367-383. Here is revealing commentary on the views of Merleau-Ponty.

Freeman WJ (1999) How Brains Make Up Their Minds. London UK: Weidenfeld & Nicolson. Here is a concise introduction to nonlinear brain dynamics.

Freeman WJ (1999) Consciousness, intentionality, and causality. Journal of Consciousness Studies 6: 143-172. Here is a complete list of my sources and references.

Freeman WJ (2005) Origin, structure, and role of background EEG activity. Part 3. Neural frame classification. Clinical Neurophysiology, in press.

Gibson JJ (1979) The Ecological Approach to Visual Perception. Boston: Houghton Mifflin. Information-based description of interactions with environments.