The Two-Stage Solution to the Problem of Free Will How Behavioral Freedom in Lower Animals Has Evolved to Become Free Will in Humans and Higher Animals

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The Two-Stage Solution to the Problem of Free Will

How Behavioral Freedom in Lower Animals Has Evolved to Become Free Will in Humans and Higher Animals

Dr. Robert O. (“Bob”) Doyle

Astronomy Department, Harvard University

Abstract. Random noise in the neurobiology of animals allows for the generation of alternative possibilities for action. In lower animals, this shows up as behavioral freedom. Animals are not causally pre-determined by prior events going back in a causal chain to the origin of the universe. In higher animals, randomness can be consciously invoked to generate surprising new behaviors. In humans, creative new ideas can be critically evaluated and deliberated. On reflection, options can be rejected and sent back for “second thoughts” before a final responsible decision and action.

We present new cosmological and microphysical reasons for doubting the deterministic picture of the world that was popular before quantum mechanics, one which still dominates philosophical discussions of free will. David Hume’s compatibilism reconciled free actions with that classical determinism. We attempt to reconcile free will with quantum indeterminism.

When the indeterminism is limited to the early stage of a mental decision, the decision itself can be described as adequately determined. This is called a two-stage model, first “free”generation of ideas, then an adequately determined “will.” We propose our Cogito model as the most plausible current explanation for human free will. We compare this model to past suggestions and situate it in the taxonomy of current free will positions.

A credible free will model may restore some balance to a disturbing social trend that considers moral responsibility impossible on the basis of philosophical reasoning, psychological studies, and advances in neuroscience.


In the 14 May 2009 issue of Nature Magazine,1 Martin Heisenberg challenged the idea, popular in the recent psychology and philosophy literature, that human free will is an illusion.2 Heisenberg suggested that a lot could be learned by looking at animals, to see how they initiate behavior. The behaviorist idea that actions are only initiated in response to external stimuli has been discredited. For decades, Watson-Skinner behaviorism ignored the existence of internal states in the mind to focus on stimulus and response, but today such internal mental states are accepted as the causes of actions, in animals and humans.

In my own correspondence with Nature in their 25 June issue,3 I connected Heisenberg’s thinking with William James’s 1884 two-stage model of free will,4 first chance generation of alternative possibilities, followed by a willed decision.

Long before twentieth-century behaviorism and logical empiricism had limited the study of the mind to externally observable phenomena, James had argued in The Dilemma of Determinism, that random chance played a role in generating alternative possibilities.

"The stronghold of the determinist argument is the antipathy to the idea of chance...This notion of alternative possibility, this admission that any one of several things may come to pass is, after all, only a roundabout name for chance."5

And James explicitly connected spontaneous variations in the Darwinian gene pool with random images and thoughts in the human brain.

“[In mental evolution], if anywhere, it would seem at first sight as if that school must be right which makes the mind passively plastic, and the environment actively productive of the form and order of its conceptions; which, in a word, thinks that all mental progress must result from a series of adaptive changes, in the sense already defined of that word...It might, accordingly, seem as if there were no room for any agency other than this; as if the distinction we have found so useful between "spontaneous variation," as the producer of changed forms, and the environment, as their preserver and destroyer, did not hold in the case of mental progress; as if, in a word, the parallel with Darwinism might no longer obtain… And I can easily show...that as a matter of fact the new conceptions, emotions, and active tendencies which evolve are originally produced in the shape of random images, fancies, accidental out-births of spontaneous variation in the functional activity of the excessively instable human brain.”6

Martin Heisenberg thus became the latest in a long list of philosophers and scientists7 who sought a “two-stage” model, a temporal sequence of first randomness, then law-like selection, as the basis for human freedom. Before Heisenberg, the question always was how to free the human brain from deterministic worries. Now that Heisenberg has extended the concept of randomly generated alternative possibilities for action throughout the animal kingdom, he has liberated all life from the complete pre-determinism implied by the Newtonian and Laplacian world view of William James’s time.

Antipathy to chance.

What William James called the “antipathy to chance” goes back 2300 years to the Stoic and Academic philosophers’ attack on Epicurus’ notion of an atomic “swerve.” Epicurus said such a random swerve was needed to break the bonds of his materialist colleague Democritus, whose strict causal physical determinism denied human freedom.8 Stoics and Academics attacked Epicurus for suggesting that human freedom was directly caused by chance. That would deny human responsibility and make our actions random, they said.9 For the Stoics, Nature was identical to God and Reason.10 To suggest that chance was real invited the atheistic thought that God was either irrational or ignorant of future events.

The standard argument against free will is the logical claim that either determinism or indeterminism is true. If the first, we are not free, if the latter, we are not responsible.11

The conceptualization of two stages in a temporal sequence is motivated by the need to answer the two objections to free will in the standard argument against it. The “adequate determinism” of the second stage defeats the problem of pre-determinism from the BIg Bang that threatens our freedom. The limiting indeterminism of the first stage is prevented from making our decisions random, which would threaten our responsibility.

We can see why so many philosophers accept the idea that determinism is “compatible” with free will. It is because given the forced choice between the determinism and indeterminism in the standard argument, determinism at least makes our actions responsive to reasons. They can be caused by our motives, feelings, and desires. They result from a non-random deliberation that evaluates our options.

What Heisenberg and many other thinkers have established is that randomness at some level or stage (the generation of alternative possibilities) need not jeopardize adequate lawlike behavior at another level or stage (the adequately determined evaluation of those possibilities).

As long ago as 1690, John Locke insisted on the separation of "free" and "will." He hoped

"to put an end to that long agitated, and, I think, unreasonable, because unintelligible, question, viz. Whether man's will be free or no? For if I mistake not, it follows from what I have said, that the question itself is altogether improper….This way of talking, nevertheless, has prevailed, and, as I guess, produced great confusion….I think the question is not proper, whether the will be free, but whether a man be free."12 [Locke's emphasis.]

A century later, David Hume “reconciled” man's freedom with determinism in the notion we now call “compatibilism.” He properly insisted that our will is determined by our motives and inclinations.

to proceed in this reconciling project with regard to the question of liberty and necessity; the most contentious question of metaphysics, the most contentious science; it will not require many words to prove, that all mankind have ever agreed in the doctrine of liberty as well as in that of necessity, and that the whole dispute, in this respect also, has been hitherto merely verbal.

"By liberty, then, we can only mean a power of acting or not acting, according to the determinations of the will; this is, if we choose to remain at rest, we may; if we choose to move, we also may. Now this hypothetical liberty is universally allowed to belong to every one who is not a prisoner and in chains. Here, then, is no subject of dispute." 13

But Hume denied that liberty depended in any way on chance. For Hume and the great mathematicians who developed the calculus of probabilities - Abraham de Moivre before Hume and Pierre-Simon Laplace after him, chance was merely human ignorance.

"liberty, when opposed to necessity, not to constraint, is the same thing with chance; which is universally allowed to have no existence."14

"Though there be no such thing as Chance in the world; our ignorance of the real cause of any event has the same influence on the understanding, and begets a like species of belief or opinion."15

Nevertheless, Hume recognized a serious objection to his theory, that everything might be pre-determined. Most compatibilists and determinists since Hobbes and Hume never mention the fact that a causal chain of events going back before our birth would not provide the kind of liberty they are looking for. But Hume frankly admits that such a causal chain would be a serious objection to his theory.

I pretend not to have obviated or removed all objections to this theory, with regard to necessity and liberty. I can foresee other objections, derived from topics which have not here been treated of. It may be said, for instance, that, if voluntary actions be subjected to the same laws of necessity with the operations of matter, there is a continued chain of necessary causes, pre-ordained and pre-determined, reaching from the original cause of all to every single volition, of every human creature. No contingency anywhere in the universe; no indifference; no liberty. While we act, we are, at the same time, acted upon. 16

Today we can finally reconcile free will with chance, randomness, and indeterminism, which alone can break this “continued chain of necessary causes.”

Randomness in cosmology and biology.

Randomness has been present in cosmology since the origin of the universe, a state of total chaos (minimal information) nearly 14 billion years ago. But mathematicians and physicists sought deterministic explanations that avoid randomness. The most famous was Pierre-Simon Laplace, who in 1815 postulated a super-intelligence that could know the positions, velocities, and forces on all the particles in the universe at one time, and thus know the universe for all times. This implies that information is a constant of nature. Some mathematicians think that information is a conserved quantity.

But midway through the 19th century, Lord Kelvin (William Thomson) realized that the newly discovered second law of thermodynamics required that information could not be constant, but would be destroyed as the entropy (disorder) increased. Hermann Helmholtz described this as the heat death of the universe.

Kelvin’s claim would be correct if the universe were a closed system. But in our open and expanding universe, David Layzer showed that the maximum possible entropy is increasing faster than the actual entropy.17 The difference between maximum possible entropy and the current entropy is called negative entropy, opening the possibility for complex and stable information structures.

Despite the second law of thermodynamics, stable and lawlike information structures evolved out of the chaos, first, in the form of microscopic particulate matter – quarks, baryons, nuclei, and electrons, then later, under the influence of gravitation – macroscopic galaxies, stars, and planets. Every new information structure reduces the entropy locally, so the second law requires an equal (or generally much greater) amount of entropy to be carried away. Without the expansion of the universe, this would be impossible.

Whether the newly formed stable structure is a baryon or a planet, the new "bits" of information can be regarded as physical "measurements" that involve the collapse of quantum mechanical wave functions. Gunter Ludwig18 and Rolf Landauer19 showed that any such measurement that increases the number of information bits must involve a compensating increase in the entropy or randomness elsewhere. For Ludwig, it was in the measurement apparatus. For Landauer, it was the energy dissipated by a computer's power supplies.

Because of the “law of large numbers” in statistics, and the correspondence principle of quantum mechanics (which says that quantum physics approaches classical physics for large quantum numbers), the Newtonian laws of classical mechanics, discovered in the stable and regular motions of the planetary orbits, are “adequately determined.” This is despite the residue of real originary chaos in many parts of the universe, especially in the quantum-mechanical microcosmos. The effects of quantum indeterminacy can thus normally be ignored in the macroscopic world.

Randomness in biology, on the other hand, plays a central role, in the evolution of species and in the life strategies of many organisms, not only animals. (Darwin was circumspect and cautious about "mere chance," because in his time chance still evoked strong atheistic sentiments.)

For example, plants distribute their seeds to remote locations taking advantage of random winds. Immobile fruit trees drop their fruit where it can be eaten by mobile animals, which carry the indigestible seeds to new locations and deposit them along with nourishing manure as fertilizer.

In animals, Heisenberg cites the bacterium Escherichia coli.20 These tiny organisms are equipped with sensors and motion capability that let them make two-stage decisions about which way to go. They can move in the direction of nutrients and away from toxic chemicals. They do this with tiny flagella in their tails that rotate in two directions. Flagella rotating clockwise cause the bacterium to tumble and face random new directions. When the flagella rotate counter-clockwise, the bacterium moves forward and sensory receptors on the bacterium surface detect gradients of chemicals and temperatures. If the gradient indicates “food ahead,” or perhaps “danger behind,” the bacterium continues straight ahead. The lawlike decision to go forward is an adequately determined evaluation of sensors along the bacterium’s body. If the sensed gradients are unsuitable, the flagella reverse and the bacterium again tumbles.

Inside animals, immune systems recruit randomness to discover antibodies for invading antigens. The white blood cells have evolved a powerful strategy to discover unique information in the antigen. What they have done is evolve a "re-sequencing" capability. Using the same gene splicing techniques that biologists have now developed to insert characteristics from one organism into another, the white blood cells have a very-high-speed process that shuffles genes around at random.21 They cut genes out of one location and splice them at random in other locations. This combinatorial diversity provides a variation in the gene pool like the Darwinian mutations that drive species evolution. The immune system gets even more random. It has a lower-level diversity generator that randomly scrambles the individual nucleotides at the junctions between genes. The splicing of genes is randomly done with errors that add or subtract nucleotides, creating what is called junctional diversity. Once antibodies are found bind to the antigen successfully, the immune system then generates large numbers of them in an adequately determined production process.

We see that even the lowest forms of animal can recruit randomness to serve their teleonomic purposes. Now Ernst Mayr has shown that evolution is conservative, reusing existing mechanisms rather than inventing new ones. So what Mayr calls the “two-step” process 22 of Darwinian evolution itself may have become a feature of living organisms up to higher animals and humans.

The mind’s “two-stage” ability to be creative and free is likely evolved indirectly from Mayr's "two-step" process and then directly from the combination of random and lawlike behavior in the lower animals. Free will is therefore not an ad hoc development in humans, as many philosophers (especially theologians) have thought. It is a normal biological property, not a gift of God or inexplicable mystery.

Evolving Levels of Selection

Getting from behavioral freedom in the lower animals to free will in humans has primarily involved significant changes in the complexity of the second stage – the selection process.

Although randomness may at all levels have the same source in chaotic thermal and quantal noise, we can note that the selection process itself has significantly evolved. So we can suggest different levels of selection (but note that at each level organisms use all the earlier levels as well).

Natural selection - for biological evolution, selection is reproductive success for a population.

Instinctive selection - by animals with little or no learning capability. Selection criteria are transmitted genetically.
Learned selection - for animals whose past experiences guide current choices. Selection criteria are acquired environmentally, including instruction by parents and peers.
Predictive selection - using imagination and foresight to evaluate the future consequences of choices.
Reflective and normative selection – in which conscious deliberation about cultural values influences the choice of behaviors.

We can see evolution adding more and more selection features over time that eventually become the many factors at work in the fully conscious human will.

Randomness in psychology and philosophy.

Although real chance was welcomed by at least one philosopher and psychologist of the nineteenth century (William James), since the twentieth-century discovery of real chance in the form of quantum indeterminacy by Werner Heisenberg (Martin’s father), randomness has not fared well in psychology or philosophy.

In his Gifford Lecture of 1927, Arthur Stanley Eddington had described himself as unable "to form a satisfactory conception of any kind of law or causal sequence which shall be other than deterministic."23 Yet just a year later, in response to Heisenberg's indeterminacy principle, Eddington revised his lectures for publication as The Nature of the Physical World. There he dramatically announced "It is a consequence of the advent of the quantum theory that physics is no longer pledged to a scheme of deterministic law," 24 He went even farther and enthusiastically identified indeterminism with freedom of the will.

But the critical reaction of philosophers was swift.25 A “free electron” has nothing to do with “free will,” they complained. A quantum event in the brain, amplified to affect our reasoning, can only make our decisions random. Quantum events simply happen to us. They are not “up to us.”26 We are not responsible for them.

A number of prominent philosophers and scientists struggled to include quantum indeterminacy in a model of free will, including Arthur Holly Compton,27 Karl Popper,28 and Henry Margenau.29 But their efforts were not convincing to the philosophical community and are rarely referenced in the free will debates.

The one living philosopher who has spent his adult career trying to explain free will as involving quantum events is Robert Kane. Kane has had some significant success showing that we can be responsible for an event even if it happens indeterministically. He considers the case of a businesswoman on the way to an important meeting when she observes an assault in an alley.30 She has excellent (moral and humanitarian) reasons to help the victim. She has equally important (practical and self-interested) reasons to continue on and advance her career.

Kane argues that whichever way the businesswoman decides, and even if the “torn decision,” as he calls it, is undetermined as a result of neural noise, she has excellent reasons to take responsibility either way. But Kane himself has not found two-stage free will models satisfying,31 and other prominent libertarians like Peter van Inwagen have said that “free will remains a mystery.”32

Some philosophers have been critical of Kane and argue that the agent cannot claim responsibility if the decision was at all random and thus a matter of “luck.” The idea of “moral luck” is the source of many moral paradoxes and dilemmas.33, 34

In 1995, Alfred Mele considered a two-stage model of free will in which indeterminism (he called it incompatibilism) is confined to the early stage.35 The latter stage he describes as “compatibilist” (effectively and adequately determined). Mele’s model is similar to one proposed in 1978 by Daniel Dennett.36 Dennett’s work incorporated the earlier ideas of David Wiggins,37 Karl Popper, and Arthur Holly Compton.

Dennett could not endorse his own two-stage decision model because he could not imagine a plausible location for quantum events in the brain, one exquisitely timed to be of help in the decision process. How could a randomly timed event be of any help? He settled instead for computer-generated random number sequences as all that is needed in his decision-making model.

In a recent book, Mele considered the problem of free will and luck,38 comparing the indeterministic early stage of his model to a neural roulette wheel in the head, with a tiny neural ball whose probabilities may be high for deciding to A, but it is still luck that it did not land in the wheel segment for B. In the end Mele, like Dennett, could not endorse the two-stage model. Note that both Kane and Mele describe a choice between two given options and then look to randomness (quantum noise or a roulette wheel ball) to help with the decision.

The basic requirements for human freedom

Freedom requires the randomness of absolute chance to break the causal chain of determinism (actually pre-determinism), yet it must provide the conscious knowledge that we are adequately determined to be responsible for our choices, that our decisions and actions are "up to us."

Freedom requires some events that are not causally determined by immediately preceding events, events that are unpredictable by any agency, events involving quantum indeterminacy.

These random events can generate alternative possibilities for action. They are the source of the creativity that adds new information to the universe. Randomness is the "free" in free will.

Freedom also requires an adequately determined will that chooses or selects from those alternative possibilities. There is effectively nothing uncertain about this choice. Adequate determinism is the determination, the "will" in free will.
Adequate determinism means that randomness in our thoughts about alternative possibilities does not directly cause our actions.

Random thoughts can therefore lead to intentions, evaluations, and decisions that are adequately determined to produce actions, for which we can take moral responsibility.

Thoughts come to us freely. Actions go from us willfully.

We must admit indeterminism, but not permit it to produce random actions as Determinists mistakenly fear.

We must also limit determinism, but not eliminate it as Libertarians mistakenly think necessary.

Evaluation and careful deliberation of all the available possibilities, both ingrained habits and creative new ideas, must help us to "determine" and thus "cause" our actions.

But event acausality somewhere is a prerequisite for any kind of agent causality that is not pre-determined.

We thus define "free will" as a two-stage creative process in which a human or higher animal freely generates alternative possibilities, some caused by prior events, some uncaused, following which the possibilities are evaluated and one is "willed," i.e., selected or chosen for adequately determined reasons, motives, or desires.

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