Here is a 13-point synopsis of a book I published in the U.S. last week: The Hidden Spring.
1. The great 19th-century physiologist Johannes Müller believed that animate organisms "contain some non-physical element or are governed by different principles than are inanimate things."
Helmholtz, Brücke, du Bois-Reymond, and others disagreed; they argued that "no other forces than the common physical and chemical ones are active within the organism." Sigmund Freud tried to establish a natural science of the mind on this basis, in which mental life could be reduced to "quantitatively determinate states of specifiable material particles." He failed in his project, lacking the methods, and abandoned it in 1896.
2. A century later, Francis Crick (1994) declared that "you, your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules." He exhorted us to try again to discover the neural correlates of consciousness, and he attempted to do so himself.
3. In response, David Chalmers (1995) argued that Crick’s search for the neural correlates of consciousness was an "easy" problem—a correlational rather than a causal one—the solution of which could explain where but not why and how consciousness arises.
For Chalmers, the "hard" problem of consciousness was: How and why do neurophysiological activities produce the experience of consciousness? For him (and his philosophical predecessor Thomas Nagel), the problem revolved around the something-it-is-like-ness of experience: "An organism has conscious mental states if and only if there is something that it is like to be that organism—something it is like for the organism." The hard problem, therefore, is this: Why and how does the subjective quality of experience arise from objective neurophysiological events?
4. To ask how objective things produce subjective things is to speak loosely; it risks making the hard problem harder than it needs to be.
Objectivity and subjectivity are observational perspectives, not causes and effects. Neurophysiological events can no more produce psychological events than lightning can produce thunder. They are parallel manifestations of a single underlying process. The underlying cause of both lightning and thunder is electricity, the lawful mechanisms of which explain them both. Physiological and psychological phenomena can likewise be reduced to unitary causes, but not to each other.
5. We usually describe the underlying causes of biological phenomena in "functional" terms, and functional mechanisms can, in turn, be reduced to physical laws.
For example, what is the mechanism of vision? However, Chalmers correctly points out that the functional mechanism of vision does not explain what it is like to see. This is because vision is not an intrinsically conscious function. The performance of visual functions (even specifically human ones, like reading) need not feel like anything. Perception readily occurs without awareness of what is perceived and learning without awareness of what is learned.
Therefore, Chalmers reasonably asked: "Why is the performance of these functions accompanied by experience? Why doesn’t all this information-processing go on 'in the dark,' free of any inner feel?" Science’s failure to answer this question raises the possibility that consciousness does not form part of the ordinary causal matrix of the universe.
6. Chalmers’s question may reasonably be asked of all cognitive functions, not only visual ones, but the same does not apply to affective functions. How can you have a feeling without feeling it? How can we explain the functional mechanism of affect without explaining why and how it causes us to experience something?
7. Against this background, it is of the utmost interest to observe that cortical functioning is accompanied by consciousness only if it is "enabled" by the reticular activating system of the upper brainstem. Damage to just two cubic millimeters of this region obliterates all consciousness.
Many people believe that this is because the brainstem modulates the quantitative level of consciousness, or "wakefulness," but that view is unsustainable. The consciousness generated by the reticular activating system has qualitative content of its own. This is affect. Since cortical consciousness is contingent upon brainstem consciousness, affect is revealed to be the foundational form of consciousness. The sentient subject is literally constituted by affect.
8. Affect is an extended form of homeostasis, which is a basic biological mechanism that arose naturally with self-organization.
Self-organizing systems survive because they occupy limited states; they do not disperse themselves. This survival imperative led gradually to the evolution of the complex dynamical mechanisms that underwrite intentionality. Crucially, the selfhood of self-organizing systems grants them a point of view. That is why it becomes meaningful to speak of the subjectivity of such a system: Deviations from their viable states are registered by the system, for the system, as needs.
9. Affect hedonically valences biological needs so that increasing and decreasing deviations from homeostatic settling points (increasing and decreasing prediction errors) are felt as unpleasure and pleasure, respectively.
Each category of need—of which there is a great variety—has an affective quality of its own, and each triggers action programs that are predicted to return the organism to its viable bounds. These active states take the form of innate reflexes and instincts, which are gradually supplemented by learning from experience in accordance with the Law of Affect, which states: "If a behavior is consistently accompanied by pleasure it will increase, and if it is consistently accompanied by unpleasure it will decrease."
Feeling by an organism of fluctuations in its own needs enables choice and thereby supports survival in unpredicted contexts. This is the biological function of experience.
10. Needs cannot all be felt at once.
They are prioritized by a midbrain decision triangle, where current needs (residual prediction errors, quantified as free energy) converging on the periaqueductal grey are ranked in relation to current opportunities (displayed in the form of a two-dimensional "saliency map" in the superior colliculi). This triggers conditioned action programs, which unfold in expected contexts over a deep hierarchy of predictions (the generative model of the expanded forebrain).
The actions that are generated by prioritized affects are voluntary, which means they are subject to here-and-now choices rather than pre-established algorithms. Such choices are felt in exteroceptive consciousness, which contextualizes affect. The choices are made on the basis of fluctuating precision-weighting (a.k.a. arousal, modulation, post-synaptic gain) of the incoming error signals that are rendered salient by prioritized needs, while they are buffered in working memory, with the aim of minimizing uncertainty (maximizing confidence) in a current prediction as to how the need can be met. This is "reconsolidation."
11. Reliably successful choices result in long-term adjustments of sensory-motor predictions.
Thus, exteroceptive consciousness is predictive work in progress, the aim of which is to establish ever deeper (more certain, less conscious) predictions as to how needs may be resolved. This long-term consolidation—and the transition from "declarative" to "non-declarative" memory systems—requires a reduction of complexity in the predictive model to facilitate generalizability.
We aspire to automaticity—absolute confidence—but we can never achieve it completely. To the extent that we fail, we suffer feelings. Since we never achieve errorless prediction, the default drive (when all goes well) is SEEKING—proactive engagement with uncertainty, with the aim of resolving it in advance. When this affect is prioritized, it is felt as curiosity and interest in the world.
12. These are the causal mechanisms of consciousness—in both its manifestations, neurological and psychological—what it looks like and what it feels like.
The underlying abstractions can be reduced to natural laws, such as Friston’s Law, which states: "All the quantities that can change, i.e., that are part of the system, will change to minimize free energy." These laws underwrite self-organization. They are no less capable of explaining how and why proactively resisting entropy (i.e., oblivion) feels like something than other scientific laws are capable of explaining other natural things. Consciousness is part of nature, and it is mathematically tractable.
13. All known conscious systems are alive, but not all living systems are conscious.
Likewise, all living systems are self-organizing, but not all self-organizing systems are alive. If the argument laid out here is correct, then, in principle, an artificially conscious self-organizing system can be engineered. Consciousness can be produced. This will realize the wildest dreams of Helmholtz and his colleagues. However, we must question our motives for doing this, accept collective responsibility for the potentially dire consequences, and proceed with extreme caution.
References
Chalmers, D. (1995) Facing up to the problem of consciousness. Journal of Consciousness Studies, 2: 200-219.
Solms, M. & Friston, K. (2018) How and why consciousness arises: some considerations from physics and physiology. Journal of Consciousness Studies, 25: 202-38.