Of Clouds, Clocks, Feedback & Free Will

By Dr. Peter C. Lugten

This article has been selected for publication in Free Inquiry magazine.

In this paper, I will demonstrate that Free Will is a genuine, real property of the human condition. I will use as context an essay by Sir Karl Popper, “Of Clouds and Clocks”, which he presented at the Arthur Holly Compton Memorial Lecture at Washington University, St. Louis, on April 21, 1965.

Many contemporary philosophers of mind and prominent neuroscientists agree that our choices are decided for us through either a “hard” or “soft” version of determinism. In the “hard” version, our actions are fully determined by the starting positions of the atoms in our brain cells when we are born, incompatible with our possessing Free Will. In the “soft” version, Free Will is to a weak extent “compatible” with a deterministic Universe. This can occur, dubiously, either through a possibility for real choice being hypothetical under certain circumstances, or if moral authorship of our actions derives from our being their original source, whether or not we have a choice. The alternative to determinism, it is feared, would be complete random chaos, where we might behave according to the whim of each moment, without any self-control. This view, together with its attempts to stifle unrestrained impulses, is called “libertarianism”, and, since it holds Free Will to be incompatible with determinism, “incompatibilism”. If any of this is correct, there could be no justification for society to hold anyone criminally responsible for bad behavior, so these ideas, clearly at odds with the legal system, are not inconsequential.

Sir Karl Popper regarded physical determinism as a nightmare. In his paper “Of Clouds and Clocks – An Approach to the Problem of Rationality and the Freedom of Man”1, Popper tried to solve the question of whether, and how, we could have moral control over our actions. Popper held that our actions are partially determined by our evolution, genetics and upbringing, and partly the result of chance; but that we exert what he calls “plastic control” over our actions in a manner which is neither random nor predetermined. Popper drew a line placing unpredictable, amorphous events on the left (clouds), and perfectly regular mechanisms (clocks) on the right. Plastic control placed humanity near the middle of such a line. 

I wish to present some contemporary ideas in neuroscience with a view to explaining my theory of the existence of Free Will. First, I must clarify what is meant by being predetermined. To some, it means that since the first particles emerged from the violence of the inchoate Universe, some superintelligence could theoretically have tracked each ones’ trajectory to know exactly where it would be right now, and could continue thus on into the future. Under this conception, if a stranger were to phone you as a wrong number, and your phone began to ring at the exact moment that your tea-kettle began to boil, this coincidence would have been preordained as inevitable. There are many reasons to deny that this is so. Popper quoted Arthur Holly Compton’s “The Freedom of Man”2 “it is no longer justifiable to use physical law against human freedom”. Compton had written the preface for Werner Heisenberg’s first book, and was well acquainted with his ideas about uncertainty. Albert Einstein was among the physicists who thought otherwise. Reacting to Heisenberg’s Uncertainty Principle, he exclaimed that God does not play dice! He believed that our uncertainty concerned only our knowledge of the quantum state, which remained deterministic due to “hidden variables”. But in 1964, John Stewart Bell proved that any quantum theory with hidden variables must be nonlocal, permitting instantaneous interaction between particles no matter how far separated.  Nonlocality is a consequence of Heisenberg’s Uncertainty.3  This brings us back full circle, to God playing dice with Einstein and determinism.4 – adapted from Appendix 1 As Professor Richard Muller wrote, in “Now: The Physics of Time”,5 respective of Heisenberg, “We can’t predict when an atom will disintegrate, and the Laws of Physics, as they currently exist, say that this failure is fundamental. If we can’t predict such a simple physical phenomenon, then how can we imagine that someday we will be able to show that human behavior is completely deterministic?” The Health Physics Society website “Are Our Bodies Radioactive” details how thousands of radioactive decays take place in our bodies each second, which is about 10% of the typical radiation we receive from our environment. This represents a lot of indeterminism. Stephen H. Kellert describes in “In the Wake of Chaos”6 such features as turbulence, chaotic dynamics, Lyapunov exponents, the fractal nature of strange attractors, and the sensitive dependence on initial conditions for systems confined to them to point out the limitation on the predictability of physical systems, which “straddles the putative line between theoretical and practical impossibility by presenting us with examples of tasks so difficult that the very fact that we are finite beings makes us unable to accomplish them”. These chaotic dynamics, otherwise known as the “butterfly effect”, mean that an unfortunate combination of indeterminist radioactive decays has probably caused a cancer that aborted the career of someone who could have gone on to change civilization.  Ilya Prigogine, in “The End of Certainty”,7 discusses how uncertainty is fundamental, though suggests the chaotic effects are more important, as they are driven by time-irreversible processes dependent on entropy. David Layzer, writing in Scientific American8, explained that as the early Universe expanded, at a rate faster than which matter and radiation could move into the new space, there were departures from thermal equilibrium which represented macroscopic information and the creation of novelty, contradicting determinism. Ruth Kastner, a strong advocate of free will, considered her Relativistic Transactional Interpretation of Quantum Mechanics to be most appropriate in defiance of Einstein’s deterministic Blocktime Universe.9 Sir Roger Penrose’s Orchestrated Objective Reduction theory of consciousness solves the problem of how athletes can make a “decision” i.e., to hit a fastball, too quickly for neurons decide, in a classical fashion, through the retroaction of quantum superposition.10 But even while denying the hard determinism of the “random phone call/ tea kettle boiling coincidence”, we could acknowledge a certain validity to the “ad hoc” determinism of the “I was raised by abusive parents in a crime-ridden neighborhood; therefore my tragic circumstances made me do it” defense. Studies have reported heritable components influencing a number of character traits including intelligence, novelty seeking, fearfulness, aggression and violence, amounting to more or less 50% of the influence on our behavior.11 We are influenced by our epigenetic history12,by our physical nature, including sex, physical aptitudes or disabilities, and by our upbringing. Accordingly, children of very rich families are likely to go to Ivy-League schools, and unlikely to sell crack on street corners. But even children from poor neighborhoods can resist the lure of gang membership, study hard, and win a scholarship. What counts is determination, not determinism.

In fact, lately, physicists and philosophers are more concerned with the nature of causation, as to whether it occurs at the fundamentally small levels of physics, if at all, or whether it occurs at the level of consciousness13. This can lead to a stance, basically deterministic from an outsider’s point of view, that being part of the causal flow (i.e., not random) is necessary for freedom, if you think that freedom is wanting to do what you had to do anyway. But if causation occurs at the level of human consciousness, we can also be free in the sense of “I made this as a genuine choice, and I could have chosen otherwise”. Others propose that Free Will, like causation, isn’t binary but comes in degrees. The percentage that isn’t predetermined by our circumstances could perhaps be measured based on our mental integration, and would be equivalent to our agency. And cognitive scientists have suggested a “Free Will index” to assess people’s capacity to rethink their actions. This could be used to ascertain if a perpetrator is less than free in an ad hoc sort of way that might respond to rehabilitation.

    Countering the “determinists” who argue that our personal genetic and environmental determinism renders us bereft of Free Will, I will argue that Popper’s “plastic control” can have a neurological basis which is able to surmount both determinism and chance through the emergent process of consciousness. In effect, what I propose is an inversion of compatibilism, compatible not with determinism but with random chance. I will consider neuroplasticity, consciousness, will, and and character leading to free will.

There can be no plastic control without neuroplasticity. The ability of conscious decisions to neuroplastically alter brain structures was investigated by research professor of psychiatry Jeffrey M. Schwartz, who was able to demonstrate that Obsessive Compulsive Disorder patients could consciously learn to reduce their symptoms. This produced physical changes to the basal ganglia of their brains which could be viewed on a PET scan. He described, with Sharon Begley, this work in “The Mind and the Brain: Neuroplasticity and the Power of Mental Force”,14 saying “The results achieved with OCD supported the notion that conscious and willful mind differs from the brain and cannot be explained solely and completely by the matter, by the material substance, of the brain… self-directed brain changes – neuroplasticity – are a genuine reality”.

Our free will dwells within the level of our consciousness. Dr. Antonio Damasio in “The Feeling of what Happens”15 described an “extended form” of consciousness in which a pattern of thoughts and expectations based on subconscious processing relate awareness of our environment to our self-awareness. In addition to containing a sensory model of the external world, the brain maps each body region such that perturbations register as sensations or feelings, and then trigger homeostatic corrections. These activities then generate their own map, which enables the individual to feel how it has been affected by the changes. This ability to feel the changes provoked by our minds allows the brain to logically infer that it is the cause, creator and owner of the body tissues, its mental feelings about those tissues, and all the activities it directs involving those tissues. The conjunction of these maps results in a “core” consciousness which is recognized as a property of the individual and which creates the “autobiographical self”. This stream of thoughts depends on a subconscious that perceives, solves and acts on problems, and, with a brief delay, conveys to the consciousness the minimum amount of information necessary to understand the situation. Studies refined by Benjamin Libet demonstrated that voluntary movements are initiated in the cerebral cortex 1/3rd of a second before we become aware of making a decision to act, and yet, during the final 150 milliseconds of this period, subjects could consciously veto a decision that had already been triggered by a wave of cortical activity. Libet wrote “Apparently, the conscious mind could intervene, in the final stages of heightened neurological activity, either to block the already initiated movement or let it pass.”16  Some researchers have argued that Libet’s and subsequent experiments measuring “readiness potentials” prove us to be subconsciously governed “zombies”, possessing a mere overlay of consciousness. These experiments have been reviewed in depth by Andrea Lavazza17, Peter Ulric Tse4 chap 9 and William R. Klemm18 chap 7, who conclude that the artificial nature of the experimental design lacks relevance to the types of decision that are important to us in real life. Alessandra Buccella and Tomas Dominik cite experiments by Uri Maoz and Liad Mudrik in 2019 that showed readiness potentials involved only in meaningless, not meaningful decisions.19 Klemm decisively argued that the subconscious can only initiate action with which it is already familiar. No one has ever subconsciously learned to ride a bicycle or play the piano; both the choice to do so, and the accomplishment of it, are painstakingly conscious examples of the exercise of free will.

Consciousness is directed. Usually, it is concerned with solving some type of problem, often abstract. Meanwhile, the subconscious may be busy performing another task, and as long as sensory input matches expectations, the task will not intrude. When the subconscious perceives a discrepancy, it jolts the consciousness to attention. 

Consciousness is left sided. In patients with surgically “split brains”, the left hemisphere, which contains the language centers, has the conscious ability to word our “inner voice”, and it is quite happy to invent lies. The left side of a “split brain” patient will communicate a false rationale for thoughts based on an unknown input provided to the right side. The necessity to  create a coherent narrative was discovered by Dr Michael Gazzaniga, described in his “Who’s in Charge? Free Will and the Science of the Brain”.20  He named the network in the left hemisphere responsible for narration “the interpreter”. However, I hope to show that the deterministic belief of Dr. Gazzaniga is wrong.

When we make a decision, either consciously or subconsciously, why do we bother to verbalize it consciously? I believe there are 3 reasons. 1) In order to justify our decisions to others, they have to be understandable in words to ourselves. 2) In order for us to be able to remember the detailed reasons for a decision, we need to store worded memories. 3) In order for the decision to be a recognizably personal one for which we accept responsibility, it must be articulated verbally, balancing pros and cons, assessing consequences and mentally preparing for them. The successful adoption of responsibility for the decision reinforces the subconscious decision-making process so that it will be more likely to make decisions in keeping with our character in the future. For instance, Stefan Bode and coworkers reported that when subjects were asked to blindly guess a certain outcome (a free decision task), fluctuating intention for one or another option may result from active competition between neural representations in the form of dynamic states of decision networks.21 Andrea Lavazza wrote “Executive functions, also known as control functions, are essential to organize and plan everyday behavior – which is not the instant behavior of Libet’s experiments…They allow us to modulate our behavior, control its development and change behavior according to environmental stimuli… Also, executive functions allow us to change behavior based on its effects, with a sophisticated feedback mechanism”.17  Studies have regionalized various character building functions to infoldings of the Frontal Cortex, for instance as described by Juri Minxha et al:22 “Decision making in complex environments relies on flexibly combining stimulus representatives with context, goals and memories…This work reveals a neuronal mechanism in the human brain whereby oscillation mediated coordination of activity between distant brain regions and accompanying changes in strength of representation and/or geometry implements task-dependent retrieval of memory”. Free Will also involves risk assessment, and one’s personal willingness to take risks. Viet Stuphorn described how studies in macaques by Ryo Sasaki et al showed that “two neighboring regions in the frontal cortex together regulate risk attitude in a competitive push-pull fashion and can both increase and decrease risk seeking”. Also, that this could be modified by inputs from other regions of the cortex.23 William R. Klemm, in “Atoms of Mind”18, p15  wrote of Circuit Impulse Patterns: “In the brain, the oscillation frequency and phase relations of electrical activity shift within and among oscillating circuits. I contend that such changes will change the nature of the thought, and, indeed, are a key component of thought itself”.  This is consistent with neural processing that makes decisions by using oscillating neural circuits to stabilize our responses to the world, thus maintaining mental homeostasis. This is performed without a central vantage point, such as the conceptual “homunculus” (or “little man”) surrounded by a “Cartesian theater”, described by Daniel Dennett .24 After all, any homunculus viewing the scene would have to answer to its own homunculus, and so on. 

Our will is guided by our character. The urge to act in a certain way is best explained by assuming a “modular theory “ for problem solving, including a Character module. It could be consistent with the “pandemonium of demons”, coordinated by a “Joycean (stream of consciousness) machine” proposed by Daniel Dennett in “Consciousness Explained”24, if the Joycean machine were conscious. It is consistent with the Avatar of William R. Klemm, in “Atoms of the Mind”, which creates a sense of self able to interact with the outside world through its integration with the subconscious. It is consistent with the circus “Ringmaster” proposed by Ian Stewart and Jack Cohen in “Figments of Reality”25, the “executive system” Peter Ulric Tse4 p 147 and the “core” consciousness of Antonio Damasio15 . According to modular theories, each potential solution to a problem or decision on how to behave next is represented by a module, or specific pattern of neural oscillations. I suspect that in choosing between them, the homeostatic function of the brain responsible for our sense of self is likely to be as finicky about maintaining a consistency of self-recognition, or personality, as it is about maintaining a steady blood pressure. Therefore, our choices will be constrained but not determined by a sense of context and consistency, and a conscious desire to maintain a sense of character and responsibility. The subconscious can choose from among several contenders what it expects to be an appropriate course, but just before acting, we become conscious of approving or vetoing it. This theory also accounts for our ability to make surprising decisions. 

The Modular-with-Feedback Theory of Free Will. My theory works in the following way. The conscious mind is a problem solving device, forever seeking answers. A common problem is “What shall I do now?” In the mind of any individual, different options will compete for enactment. Ideas that are out of keeping with character will not recur with great frequency. That I could run down the street singing “Hallelujah!” will not get very far. But ideas in keeping with character, such as putting on the kettle, or phoning so-and-so, will compete with repetitive excitation of oscillating modular nerve patterns until the pattern representing one idea is able to inhibit the other, expand to dominate the cortex, and exceed the threshold for implementation. Thus we can see that our likely behavior is predetermined by our history, which will cause some neural circuits to oscillate more strongly than others. But in their competition, each must be assigned a probability, and our actual behavior will depend on the dominance of that probability at any moment. Similarly, it is unlikely that England will lose a soccer match to San Marino, but the possibility can’t be ruled out, as in England losing to the USA in the famous 1950 World Cup match at Belo Horizonte.

In order for the Modular theory to generate Free Will, I propose a dynamic version involving feedback loops. Consider the problem of crossing a busy street. If we assume both a degree of urgency, and an approaching vehicle, we can suppose that the person of reckless character would dash right out, while a timid personality would wait for the vehicle to pass. In the reckless person, the “Go” module would oscillate with greater frequency than the “Wait”, and quickly cross the threshold to action. In the timid person, vice versa. A third, indecisive person, might have oscillations of equal frequency, and be unable to decide until changing  sensory input renders dashing out to be untenable. Feedback can occur if our impetuous road-crosser is nearly run over, with a screech of brakes and a loud cursing from the vehicle’s driver. The reckless character, now chastised, may consciously reset the oscillation frequencies of the modules to be more cautious next time. The same feedback applies not only to snap decisions, but also to decisions emanating from our moral core. Consider Artie, who has found a wallet containing $500 on the back seat of a taxi. Having turned it in, Artie is rewarded with only a thank-you, but has a good feeling about it. Coincidently, 3 months later, in another cab, the same thing happened. At this point, Artie is unemployed, and would have really appreciated a cash reward. The good feeling has evaporated. A month later, facing eviction and now unable to afford a cab, Artie sees a man up ahead drop his wallet on the sidewalk. On inspection, it also contains $500. This time, the module suggesting that Artie pockets the wallet drowns out the module for crying “Hey, Mister, you dropped your wallet!”, and, whether or not the decision is already made, Artie consciously declines a veto and walks away with the wallet. Artie recognizes that her character has changed, even if only temporarily, as a result of feedback from experience.

My Modular-with-Feedback Theory predicts that, through a consideration of the state of being undecided, we can show that the modular mechanism cannot possibly be predetermined. You are sure the answer to the last multiple choice question in the exam must be either (a) or (d), and the neural modules for each oscillate at around 50% without reaching the threshold to decide on the answer. Suddenly the docent says to put all pencils down, and your “hurry up and decide” module intervenes to choose whichever pattern was dominating at that moment. Unless one holds to determinism of the “random phone call/ kettle boiling coincidence” variety, the choice of either (a) or (d) could not be foreseeable even in principle. It seems possible that advances in technology may allow for experiments of this kind.

These ideas are consistent with those of neuroscientist William R. Klemm, who wrote “Ultimately, the belief systems that have been embraced by the conscious mind can serve to reprogram our subconscious” 18 p279. Other philosophers have arrived at a similar conclusion. Alan E. Johnson, in “Free Will and Human Life”26 provides an excellent history of the philosophical debate, concluding that “it is possible, in most cases, to change one’s characteristics by a conscious determination to do so…”, and, “we can normally exercise some degree of free will in most circumstances and work to improve our capacity for free will in other circumstances”. Stephen Kosslyn, in a forward to a 2005 book by Benjamin Libet, wrote: “In addition, “what one is” governs how one actually makes the decision. And making that decision and experiencing the actual consequences in turn modifies “what one is”, which then affects…how one makes decisions in the future”. 27 Robert O. (Bob) Doyle in “Free Will: The Scandal in Philosophy”,28 proposed a two-stage model of free will in which random options in the subconscious were to be chosen between in a deterministic manner, consciously, yielding, he claimed, adequate determination. In fact, Doyle recognized, on his website “Information Philosophy”, that two dozen philosophers, going back to William James in 1884, have proposed similar two-stage models. They all suffer the flaw, lacking the element of feedback, that they simply add a deterministic layer to a random one, and claim, thereby, to have created something which is neither, when it is, in fact, both. Lacking the element of feedback, they do not offer a way to change the character of one’s deterministic layer.

Peter Ulric Tse4  provided a neural mechanism, called Criterial Causation, whereby neural communications at synapses can change the criteria by which they will be activated in the future. Neurons accept input from many sources, and then, due to a property of NMDA synaptic receptors, may activate the next neuron in line. It may also change the criteria, or input that it selects, that will cause it to be activated next time, either in the near or distant future. These non-arbitrary outcomes are not predictable, generating novelty even while tied to preset criteria for firing. Criterial Causation, Tse wrote, “offers a middle path between determinism and randomness”p131 Unconscious systems can specify new solutions to meet now modified criteria through a 3 step process. First, new criteria are set, then variable input arrives, culminating in postsynaptic neurons, based on whether criteria are met, firing or not. The first two steps allow randomness, but not the third. In choice-making, the “executive system” creates propositional criteria in working memory, while unconscious systems offer up possibilities that more or less match. Rejection modifies the criteria, and then new solutions are offered.p147 This is almost identical to the idea I am proposing, though Tse considers the modular oscillations to be epiphenomena.  His book doesn’t place emphasis on our training of the subconscious through feedback, in a way that shapes our character. Tse mentions that the executive decision to stop the process and make a decision is an event both random and adequately determined, with the ringing of a phone at just the right moment being able to perturb the process. Tse considers his theory to be an incompatibilist physical libertarianism, a concept that has been criticized for claiming adequate partial determinism merely by superimposing determinism over randomness. In a sense, Tse could be said to have “fixed” libertarianism, but I prefer to say that his theory, like mine, is an inverse compatibilism: compatible not with determinism, but with random indeterminism.           

Returning to my theory, observe that it also explains weak will, recognized by Aristotle as “akrasia”, and in our kitchens by the strong desire to eat the extra slice of cake. In this case, the battle between the “Eat” and the “Don’t” modules can be swayed over time by the combination of the illness we feel after indulging, and the ability of our minds, over time, to harness feelings of disgust and fortify our will power. However, the fact is that there are pathological conditions that can disrupt our self control. 

Typically, addictions can disrupt the neurophysiology of the “reward system” in the brainstem, with its associated neurotransmitters of dopamine, noradrenaline and serotonin, in a way that interferes with or even perverts the normal feedback process whereby the character-module attempts to suppress unwanted urges. Free will of the addict exists, but is compromised by the disease, just as our ability to throw a ball is compromised by a broken arm. Free will is also sensitive to hunger and tiredness (being “hangry”), and the resultant “ego-depletion” described by Daniel Kahneman and Amos Tversky29. To maintain consistency of character, one should reconsider, where possible, decisions made in anger, and even adopt the old trick of counting up to ten before blurting out a regrettable remark.

Interestingly, Sir Karl Popper noted that determinism was objectionable also because it destroyed the idea of creativity, reducing to a complete illusion the idea that in preparing his lecture, he had used his brain to create something new. My belief is that the mechanism of oscillating modules representing ideas, competing for attention, that gives us plastic control of our will, is the same as that which can generate a sudden “flash of inspiration”. This occurs when a subconscious problem-solving module suddenly links to a module representing a solution that one never would have consciously expected. It is also a vital part of a sense of humor, and the art of witty extemporization. No plausible mental model has been proposed whereby these surprising insights could be predetermined, yet physician Edward de Bono, author of “Lateral Thinking: Creativity Step by Step”30 has demonstrated how we can train our minds to facilitate the experience. It would be difficult to argue, based on our ignorance of the subconscious, that we could have “flashes of inspiration”, but not possess Free Will. 

To conclude, I believe I have shown that we are adequately but incompletely determined. At the same time Free Will, resulting from the plastic control predicted by Popper and based on subconscious modular mechanisms which are subject to conscious feedback, is genuinely able to both maintain consistency of character and to, on occasion, extemporize. We are Free because the mechanism allows us to choose, and Responsible because the mechanism governing our choice, being weighted by our previous choices, allows us to feel that the choice was ours. The extent of the role of chance, or generative uncertainty in the decision making, is hidden by the mechanism, but is sufficient to preclude determinism. In effect, the Modular-with-Feedback Theory of Free Will claims for us Freedom through a plastic control the uncertainty of which we don’t fully understand, but for which we feel an emotional need. Through this mechanism for the plastic control of our will, we are neither Clouds nor Clocks, but in between them, Free.

References

  1. Sir Karl Popper. Of Clouds and Clocks. An Approach to the Problem of Rationality and the Freedom of Man; in: Objective Knowledge: An Evolutionary Approach; Oxford University Press, Revised, 1972
  2. Arthur Holly Compton. The Freedom of Man; Yale University Press, 1935
  3. Jonathan Oppenheim, Stephanie Wohler. The Uncertainty Principle determines the nonlocality of quantum mechanics; Science, Vol 330, No 6007, pp 1072-1074, 19 Nov, 2010.
  4. Peter Ulric Tse. The Neural Basis of Free Will, MIT Press, 2013
  5. Richard A. Muller. Now: The Physics of Time; W.W. Norton & Co., 2016
  6. Stephen H. Kellert. In the Wake of Chaos: Unpredictable Order in Dynamic Systems; Chicago University Press, 1993
  7. Ilya Prigogine. The End of Certainty. Time, Chaos and the New Laws of Nature; Free Press, 1997
  8. David Layzer. The Arrow of Time; Scientific American, December 1975, pp 56-69
  9. Ruth E. Kastner. The Transactional Interpretation of Quantum Mechanics. Cambridge University Press, 2013
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  15. Antonio Damasio. The Feeling of What Happens; Harcourt Brace, 1999
  16. Benjamin Libet. Does the Brain Have a Will of its Own?; The Sciences, Mar/ April 1989, pp32-35
  17. Andrea Lavazza. Free Will and Neuroscience: From Explaining Freedom Away to New Ways of Operationalizing and Measuring It; Front. Hum. Neurosci. 1 Jun, 2016
  18. William R. Klemm. Atoms of Mind: “The Ghost in the Machine” Materializes; Springer, 2011
  19. Alessandra Buccella, Tomas Dominik. Free Will Is Only an Illusion if You Are, Too. Scientific American.com January 16, 2023
  20. Michael Gazzaniga. Who’s in Charge? Free Will and the Science of the Brain; Harper Collins, 2011
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  22. J. Minxha et al. Flexible recruitment of memory based choice representations in the human medial frontal cortex; Science368 eaba 3313(2020)
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  24. Daniel Dennett. Consciousness Explained; Little, Brown & Co., 1991
  25. Ian Stewart, Jack Cohen. Figments of Reality; Cambridge, 1997
  26. Alan E. Johnson. Free Will and Human Life; Philosophia Publications, 2021
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  28.  Robert O. (Bob) Doyle. Free Will: The Scandal in Philosophy; Cambridge, MA: I-Phi Press, 2011
  29. Daniel Kahneman. Thinking Fast and Slow; Farrar, Straus and Giroux, 2011
  30. Edward de Bono. Lateral Thinking: Creativity Step by Step; Harper & Row, 1970