In 1884 James asked some Harvard Divinity School students to consider his choice for walking home after his talk.

"What is meant by saying that my choice of which way to walk home after the lecture is ambiguous and matter of chance?...It means that both Divinity Avenue and Oxford Street are called but only one, and that one either one, shall be chosen."

James also asked the students to imagine his actions repeated in exactly the same circumstances, a condition which is regarded today as one of the great challenges to libertarian free will. In the following passage, James anticipates much of modern philosophical modal reasoning and physical theories of multiple universes.

"Imagine that I first walk through Divinity Avenue, and then imagine that the powers governing the universe annihilate ten minutes of time with all that it contained, and set me back at the door of this hall just as I was before the choice was made. Imagine then that, everything else being the same, I now make a different choice and traverse Oxford Street. You, as passive spectators, look on and see the two alternative universes,--one of them with me walking through Divinity Avenue in it, the other with the same me walking through Oxford Street. Now, if you are determinists you believe one of these universes to have been from eternity impossible: you believe it to have been impossible because of the intrinsic irrationality or accidentality somewhere involved in it. But looking outwardly at these universes, can you say which is the impossible and accidental one, and which the rational and necessary one? I doubt if the most ironclad determinist among you could have the slightest glimmer of light on this point."

James’s two-stage model effectively separates chance (the indeterministic free element) from choice (an arguably determinate decision that follows causally from one’s character, values, and especially feelings and desires at the moment of decision). In The Principles of Psychology, James said there were five types of decision. In the first, the reasonable type,

"arguments for and against a given course seem to settle themselves in the mind and to end by leaving a clear balance in favor of one alternative…. In this easy transition from doubt to assurance we seem to ourselves almost passive; the reasons which decide us appearing to flow in from the nature of things, and to owe nothing to our will. We have, however, a perfect sense of being free, in that we are devoid of any feeling of coercion…. It may be said in general that a great part of every deliberation consists in the turning over of all the possible modes of conceiving the doing or not doing of the act in point. The moment we hit upon a conception which lets us apply some principle of action which is a fixed and stable part of our Ego, our state of doubt is at an end."

"We learn all our possibilities by the way of experience. When a particular movement, having once occurred in a random, reflex, or involuntary way, has left an image of itself in the memory, then the movement can be desired again, proposed as an end, and deliberately willed.

"A supply of ideas of the various movements that are possible left in the memory by experiences of their involuntary performance is thus the first prerequisite of the voluntary life."

"In the fifth and final type of decision, the feeling that the evidence is all in, and that reason has balanced the books, may be either present or absent. But in either case we feel, in deciding, as if we ourselves by our own wilful act inclined the beam; in the former case by adding our living effort to the weight of the logical reason which, taken alone, seems powerless to make the act discharge; in the latter by a kind of creative contribution of something instead of a reason which does a reason's work."

James was the only thinker with such a model in the nineteenth century. In the twentieth and twenty-first, eight more philosophers and scientists, mostly independent of one another, and apparently unaware of James work, devised similar two-stage models that separate "free" from "will." They include the French mathematician and scientist Henri Poincaré (about 1906), the physicist Arthur Holly Compton (1931, 1955), the philosopher Karl Popper (1965, 1977), the physicist and philosopher Henry Margenau (1968, 1982), the philosophers Daniel Dennett (1978), Robert Kane, (1984), and Alfred Mele (1995), and most recently, the neurogeneticist and biologist Martin Heisenberg (2009), son of the physicist Werner Heisenberg.

Poincaré speculated on how his mind works when he is solving mathematical problems. He had the critical insight that random combinations and possibilities are generated, some in an unconscious way with chance involved, then they are selected among, perhaps initially also by an unconscious process, but then by a definite conscious process of validation.

"It is certain that the combinations which present themselves to the mind in a kind of sudden illumination after a somewhat prolonged period of unconscious work are generally useful and fruitful combinations… all the combinations are formed as a result of the automatic action of the subliminal ego, but those only which are interesting find their way into the field of consciousness… A few only are harmonious, and consequently at once useful and beautiful, and they will be capable of affecting the geometrician's special sensibility I have been speaking of; which, once aroused, will direct our attention upon them, and will thus give them the opportunity of becoming conscious… In the subliminal ego, on the contrary, there reigns what I would call liberty, if one could give this name to the mere absence of discipline and to disorder born of chance."

Years later, Compton clarified the two-stage nature of his idea in an Atlantic Monthly article in 1955.

"A set of known physical conditions is not adequate to specify precisely what a forthcoming event will be. These conditions, insofar as they can be known, define instead a range of possible events from among which some particular event will occur. When one exercises freedom, by his act of choice he is himself adding a factor not supplied by the physical conditions and is thus himself determining what will occur. That he does so is known only to the person himself. From the outside one can see in his act only the working of physical law. It is the inner knowledge that he is in fact doing what he intends to do that tells the actor himself that he is free."

"The idea that the only alternative to determinism is just sheer chance was taken over by Schlick, together with many of his views on the subject, from Hume, who asserted that

'the removal' of what he called 'physical necessity' must always result in 'the same thing with chance. As objects must either be conjoin'd or not, . . . 'tis impossible to admit of any medium betwixt chance and an absolute necessity'.

"I shall later argue against this important doctrine according to which the alternative to determinism is sheer chance. Yet I must admit that the doctrine seems to hold good for the quantum-theoretical models which have been designed to explain, or at least to illustrate, the possibility of human freedom. This seems to be the reason why these models are so very unsatisfactory.

"Compton himself designed such a model, though he did not particularly like it. It uses quantum indeterminacy, and the unpredictability of a quantum jump, as a model of a human decision of great moment. It consists of an amplifier which amplifies the effect of a single quantum jump in such a way that it may either cause an explosion or destroy the relay necessary for bringing the explosion about. In this way one single quantum jump may be equivalent to a major decision. But in my opinion the model has no similarity to any rational decision, being probabilistic and involving quantum uncertainty.

"Hume's and Schlick's ontological thesis that there cannot exist anything intermediate between chance and determinism seems to me not only highly dogmatic (not to say doctrinaire) but clearly absurd; and it is understandable only on the assumption that they believed in a complete determinism in which chance has no status except as a symptom of our ignorance."

"freedom is not just chance but, rather, the result of a subtle interplay between something almost random or haphazard, and something like a restrictive or selective control."

"New ideas have a striking similarity to genetic mutations. Now, let us look for a moment at genetic mutations. Mutations are, it seems, brought about by quantum theoretical indeterminacy (including radiation effects). Accordingly, they are also probabilistic and not in themselves originally selected or adequate, but on them there subsequently operates natural selection which eliminates inappropriate mutations. Now we could conceive of a similar process with respect to new ideas and to free-will decisions, and similar things.

"That is to say, a range of possibilities is brought about by a probabilistic and quantum mechanically characterized set of proposals, as it were - of possibilities brought forward by the brain. On these there then operates a kind of selective procedure which eliminates those proposals and those possibilities which are not acceptable to the mind."

Then in 1982, with co-author Lawrence LeShan, Margenau called his model of free will a "solution" to what had heretofore had been seen as mere "paradox and illusion." He very neatly separates "free" and "will" in a temporal sequence, as William James had done, naming them simply "chance" followed by "choice."

"Our thesis is that quantum mechanics leaves our body, our brain, at any moment in a state with numerous (because of its complexity we might say innumerable) possible futures, each with a predetermined probability. Freedom involves two components: chance (existence of a genuine set of alternatives) and choice. Quantum mechanics provides the chance, and we shall argue that only the mind can make the choice by selecting (not energetically enforcing) among the possible future courses."

Dennett named his model of decision-making "Valerian" after the poet Paul Valery, who took part in a 1936 conference in Paris with Jacques Hadamard. The conference focused on Henri Poincare’s two-stage approach to problem solving, in which the unconscious generates random combinations. In his book, The Psychology of Invention in the Mathematical Mind, Hadamard quoted Valery (as did Dennett later ), summarizing the conference opinion,

"It takes two to invent anything. The one makes up combinations; the other one chooses, recognizes what is important to him in the mass of things which the former has imparted to him."

Dennett makes his version of a two-stage model very clear. And he defends it with six excellent reasons. His arguments are more persuasive than any other philosopher or scientist, including William James himself. Ironically, Dennett remains a firm believer in determinism and calls himself a compatibilist.

"The model of decision making I am proposing has the following feature: when we are faced with an important decision, a consideration-generator whose output is to some degree undetermined produces a series of considerations, some of which may of course be immediately rejected as irrelevant by the agent (consciously or unconsciously). Those considerations that are selected by the agent as having a more than negligible bearing on the decision then figure in a reasoning process, and if the agent is in the main reasonable, those considerations ultimately serve as predictors and explicators of the agent's final decision."

1. "First...The intelligent selection, rejection, and weighing of the considerations that do occur to the subject is a matter of intelligence making the difference."

2. "Second, I think it installs indeterminism in the right place for the libertarian, if there is a right place at all."

3. "Third...from the point of view of biological engineering, it is just more efficient and in the end more rational that decision making should occur in this way."

4. "A fourth observation in favor of the model is that it permits moral education to make a difference, without making all of the difference."

5. "Fifth - and I think this is perhaps the most important thing to be said in favor of this model - it provides some account of our important intuition that we are the authors of our moral decisions."

6. "Finally, the model I propose points to the multiplicity of decisions that encircle our moral decisions and suggests that in many cases our ultimate decision as to which way to act is less important phenomenologically as a contributor to our sense of free will than the prior decisions affecting our deliberation process itself: the decision, for instance, not to consider any further, to terminate deliberation; or the decision to ignore certain lines of inquiry.

"These prior and subsidiary decisions contribute, I think, to our sense of ourselves as responsible free agents, roughly in the following way: I am faced with an important decision to make, and after a certain amount of deliberation, I say to myself: "That's enough. I've considered this matter enough and now I'm going to act," in the full knowledge that I could have considered further, in the full knowledge that the eventualities may prove that I decided in error, but with the acceptance of responsibility in any case."

Kane was actually quite bleak about the possibilities for a satisfactory libertarian model. He felt

"that any construction which escaped confusion and emptiness was likely to fall short of some libertarian aspirations - aspirations that I believe cannot ultimately be fulfilled." (p.165)

His model was a choice between "relativistic alternatives." The choice was in part rational and in part random. It could be explained by the agent giving his reasons. Even if the choice is by chance,

"the agent has agreed beforehand to accept the chance selected outcome and to endorse reasons for it in a special way. That is, the selection is going to be 'willed to be so' on a provisional basis by the agent, whichever way it goes." (p.96)

Although the two-stage model of earlier thinkers is an "essential and important part" of any adequate libertarian conception of free will, it does not go far enough because it does not fully capture the notion of ultimate responsibility (Kane's UR) during rare "self-forming actions (SFAs). It is merely a "significant piece in the overall puzzle of a libertarian freedom." (p.104)

"The reason is that the chance ("free") part is not in the control of the agent and the "will" part is fully determined by a combination of the chance part and other determining factors, so the final choice is determined by factors, none of which the agent has control over at the time of choice. If all of our choices are determined at the time of choice that would not be libertarian freedom even if some chance events in the past were responsible for forming some of the determining factors that now determine our choice because however the determining factors were formed in the past, all of our choices would be determined when they are made." (personal communication)

Perhaps more important, Kane wants free choices to be "moral choices." This we believe is an ethical fallacy. Free will is a prerequisite for responsibility in the sense of accountability, the extent to which the agent's actions are in the causal chain of actions. That is an empirical question. moral responsibility is an ethical question. We must not confuse "ought" with "is."

Kane's latest suggestion for his occasional self-forming actions argues that the tension and uncertainty in our minds stirs up "chaos" that is sensitive to micro-indeterminacies at the neuronal level.

All free acts do not have to be undetermined on the libertarian view, but only those acts by which we made ourselves into the kinds of persons we are, namely the "will-setting" or "self-forming actions" (SFAs) that are required for ultimate responsibility. (p.26)

Now I believe these undetermined self-forming actions or SFAs occur at those difficult times of life when we are torn between competing visions of what we should do or become. Perhaps we are torn between doing the moral thing or acting from ambition, or between powerful present desires and long-term goals, or we are faced with difficult tasks for which we have aversions.

note that SFAs are cases of the "liberty of indifference"

In all such cases, we are faced with competing motivations and have to make an effort to overcome temptation to do something else we also strongly want. There is tension and uncertainty in our minds about what to do at such times, I suggest, that is reflected in appropriate regions of our brains by movement away from thermodynamic equilibrium — in short, a kind of "stirring up of chaos" in the brain that makes it sensitive to micro-indeterminacies at the neuronal level. The uncertainty and inner tension we feel at such soul-searching moments of self-formation is thus reflected in the indeterminacy of our neural processes themselves. What we experience internally as uncertainty about what to do on such occasions would then correspond physically to the opening of a window of opportunity that temporarily screens off complete determination by influences of the past. (p.26)

But Kane wants to keep his rationality and control at the same time as his chance element, just as he has argued since the 1980's.

"Just as indeterminism need not undermine rationality and voluntariness of choices, so indeterminism in and of itself need not undermine control and responsibility. (p.27)

"If indeterminism is involved in a process so that its outcome is undetermined, one might argue that the outcome must merely happen and therefore cannot be somebody's choice. But there is no reason to assume such a claim is true. A choice is the formation of an intention or purpose to do something. It resolves uncertainty and indecision in the mind about what to do. Nothing in such a description implies that there could not be some indeterminism in the deliberation and neural processes of an agent preceding choice corresponding to the agent's prior uncertainty about what to do. Recall from the preceding arguments that the presence of indeterminism does not mean the outcome happened merely by chance and not by the agent's effort. Self-forming choices are undetermined, but not uncaused. They are caused by the agent's efforts. (p.33)

So does Kane see that the determining element is the agent's final choice? Since he is primarily interested in cases of "liberty of indifference," the strong indeterminism might raise the objection of loss of control, but Kane says the agent can beforehand decide to assume reponsibility whichever way she randomly chose. This seems more like rationalization than reason, but Kane defends it.

"Suppose we were to say to such persons: 'But look, you didn't have sufficient or conclusive prior reasons for choosing as you did since you also had viable reasons for choosing the other way.' They might reply. 'True enough. But I did have good reasons for choosing as I did, which I'm willing to stand by and take responsibility for. If these reasons were not sufficient or conclusive reasons, that's because, like the heroine of the novel, I was not a fully formed person before I chose (and still am not, for that matter). Like the author of the novel, I am in the process of writing an unfinished story and forming an unfinished character who, in my case, is myself.'" (p.41-2)

Here at last a significant role for the swerve leaps to the eye. For it is to answer just this question, according to Cicero, that the swerve was introduced. The evident power of the self and its volitions to intervene in the physical processes of soul and body would be inexplicable if physical laws alone were sufficient to determine the precise trajectory of every atom. Therefore physical laws are not sufficient to determine the precise trajectory of every atom. There is a minimal degree of physical indeterminism — the swerve. An unimpeded atom may at any given moment continue its present trajectory, but equally may `swerve' into one of the adjacent parallel trajectories.

As far as physics is concerned there is simply no reason for its following one rather than another of these trajectories. Normally, then, the result will be, in this minimal degree, random. But in the special case of the mind there is also a non-physical cause, volition, which can affect the atoms of which it is a property.

It does so, we may speculate, not by overriding the laws of physics, but by choosing between the alternative possibilities which the laws of physics leave open. In this way a large group of soul atoms might simultaneously be diverted into a new pattern of motion, and thus radically redirect the motion of the body. Such an event, requiring as it does the coincidence of numerous swerves, would be statistically most improbable according to the laws of physics alone. But it is still, on the swerve theory, an intrinsically possible one, which volition might therefore be held to bring about. For a very similar thesis relating free will to modern quantum indeterminism, see A. S. Eddington, The nature of the physical world (1928). (It may be objected that swerves are meant to be entirely uncaused; but...that was only an inference by Epicurus' critics, made plausible by concentrating on the swerve's cosmogonic function...for there it must indeed occur at random and without the intervention of volition.)

"it might be worth exploring the possibility of combining a compatibilist conception of the later parts of a process issuing in full blown, deliberative, intentional action with an incompatibilist conception of the earlier parts. For example, it might be possible to gain "ultimate control" while preserving a considerable measure of nonultimate agential control by treating the process from proximal decisive better judgment through overt action in a compatibilist way and finding a theoretically useful place for indeterminacy in processes leading to proximal decisive better judgments".

Mele sees that chance need not be the direct cause of action

"That a consideration is indeterministically caused to come to mind does not entail that the agent has no control over how he responds to it".

Since the indeterminacy principle was his father’s work, Heisenberg’s position that the physical universe is no longer determined and that nature is inherently unpredictable comes as no surprise. What is unusual is that Heisenberg finds evidence of free behavior in animals, including some very simple ones such as Drosophila, on which he is a world expert. Heisenberg argues for some randomness even in unicellular bacteria, followed by more lawful behaviors such as moving toward food.

"Evidence of randomly generated action — action that is distinct from reaction because it does not depend upon external stimuli — can be found in unicellular organisms. Take the way the bacterium Escherichia coli moves. It has a flagellum that can rotate around its longitudinal axis in either direction: one way drives the bacterium forward, the other causes it to tumble at random so that it ends up facing in a new direction ready for the next phase of forward motion. This 'random walk' can be modulated by sensory receptors, enabling the bacterium to find food and the right temperature."

"the activation of behavioural modules is based on the interplay between chance and lawfulness in the brain. Insufficiently equipped, insufficiently informed and short of time, animals have to find a module that is adaptive. Their brains, in a kind of random walk, continuously preactivate, discard and reconfigure their options, and evaluate their possible short-term and long-term consequences.

"The physiology of how this happens has been little investigated. But there is plenty of evidence that an animal’s behaviour cannot be reduced to responses. For example, my lab has demonstrated that fruit flies, in situations they have never encountered, can modify their expectations about the consequences of their actions. They can solve problems that no individual fly in the evolutionary history of the species has solved before. Our experiments show that they actively initiate behaviour."

The leading Libertarian model is that of Robert Kane and his followers Laura Waddell Ekstrom and Mark Balaguer. They and Kane's critic Richard Double have all reached for the impossible dream of genuine indeterminacy in the "moment of choice," while achieving agential control over actions.

Double started out trying to justify the three Kane conditions for free will - control, rationality, and dual/plural alternative possibilities that allow the agent to choose otherwise in exactly the same circumstances.

But in the end Double concluded that these three conditions could not be met by Kane's model and said so in his 1990 book The Non-Reality of Free Will. To be sure, Double may have thrown in his lot with "Impossibilists" like Derk Pereboom and Saul Smilansky because he shared their goals to deny moral responsibility and eliminate moral "desert" and retributive punishment.

The leading Compatibilists to have proposed (but not endorsed) a two-stage model are Daniel Dennett and Albert Mele.

The Cogito model is less "free" than the Libertarian models, but more responsible.

The Cogito model is less "determined" (not at all predetermined) than the Compatiblist models, but more creative.

The Cogito model is less "event-causal" and more "agent causal." The agent has creative powers in the extended "moment of choice" that are like those sought by Libertarians Roderick Chisholm, Richard Taylor, and Keith Lehrer.

Nothing in the events of the "fixed past" (and the laws of nature, as compatibilists like to say) immediately preceding the "moment of choice" predetermines the agent's decision. The Cogito model lets the agent choose otherwise in exactly the same circumstances.