It will be useful to begin our discussion of the reconcilability of the concept of "action of one's own free will" with scientific determinism by a discussion of the so-called Hume—Mill solution. In this tradition, it will be remembered, the problem appears as one concerning the compatibility of personal responsibility with the principle that every event has a cause. The fundamental move is to distinguish between causation and compulsion, and to argue that, while action of one's own free will is, of course, incompatible with compulsion, it is thought by Libertarians to be incompatible with causation because they have taken causation to be a form of or to involve compulsion. Action of one's own free will is no more to be equated with uncaused action than causation is with compulsion. As the Hume—Mill tradition sees it, two pairs of opposites, "free"—"compelled," "uncaused"—"caused" are collapsed by the Libertarian into one.

Now there is certainly something of value in this way of approaching the problem, but it simply won't do as it stands. A series of comments, most of which are recognized, either explicitly or implicitly, by the tradition, will set the stage for a discussion of the problem as it exists today.

The first thing to be noted is that the term "cause," as it appears in this argument, has a technical meaning, which by no means corresponds to that which it has in everyday life. The point is a familiar one, but it should at least be mentioned because it is a paradigm example of the role of ambiguity in the free-will issue.

As Collingwood and others have pointed out, causation in the ordinary sense is the idea of the intervention of an agent in a system, thereby bringing about changes which would not otherwise have occurred. The root metaphor, to use Pepper's invaluable expression, is that of a person bringing it about that another person or a group of persons does something which the first person wishes to have done. It is worth noting, therefore, that this root metaphor is essentially that of compulsion. That this root metaphor is by no means completely "frozen" undoubtedly accounts, at least in part, for the fact that many philosophers find it simply "absurd" that an action which was caused could be done of the agent's own free will. It might also be added that, in this sense of causation, it is simply not the case that every episode has a cause. The king who causes a prisoner to be brought before him is not himself caused to make this move.

The practical sense of causation in its application to nature was gradually "depersonalized" into the analogical concept of a non-person — a merely material thing — intervening in a system of non-persons - other merely material things — bringing about changes which would not otherwise have occurred. Familiar examples arc to be found in the areas of mechanics and electrodynamics: the cue ball in a break; a thermostat in a heating system. Notice, however, as Collingwood has emphasized, that persons hover in the background of even this ostensibly depersonalized sense of the term. The cause may not be a person, but it is conceived of as manipulable by a person, at least in principle, and the objects involved are cut up, from this point of view, into that which intervenes and the remainder which constitute the system under intervention. This fact, as I see it, is essential to understanding what is ordinarily meant by a causal explanation. Not even in this extended sense is it true that every event has a cause. Furthermore, an event which is not in this sense caused need not therefore be a brute matter of fact, an unintelligible happenstance. Common sense and science alike make constant use of the concept of a system which changes in intelligible ways in the absence of external intervention.

We shall have more to say at a later stage in the argument about the intelligibility of episodes which do not have intervening causes. Our next move must be to give a more adequate formulation of the Hume–Mill approach against the background of the above distinctions. In this reformulation, the intelligibility of episodes becomes their predictability, and determinism, although still couched in terms of "cause," becomes the thesis that all episodes are in principle predictable.

It is often thought that universal predictability is an incoherent notion. The problem arises at two levels: (a) the level defined by the common sense framework of persons; (b) the level defined by the framework of micro-physical theory. I shall be concerned with the place of predictability in the framework of persons shortly. As for (b), and abstracting from scientific issues pertaining to quantum mechanics, conceptual difficulties do arise about universal predictability if we fail to distinguish between what I shall call epistemic predictability and logical predictability. By epistemic predictability, I mean predictability by a predictor in the system. The concept of universal epistemic predictability does seem to he bound up with difficulties of the type explored by Gödel. By logical predictability, on the other hand, is meant that property of the process laws governing a physical system which involves the derivability of a description of the state of the system at a later time from a description of its state at an earlier time, without stipulating that the latter description be obtained by operations within the system. It can be argued, I believe, with considerable force, that the latter is a misuse of the term "predictability," but it does seem to me that this is what philosophers concerned with the free will and determinism issue have had in mind, and it simply muddies up the waters to harass these philosophers with Gödel problems about epistemic predictability.

Returning now to the Hume–Mill gambit, we see that the point is well taken that, if causality is construed in terms of predictability rather than intervention, then the fact that an action is caused does not imply that it is compelled. On the other hand, the overtones of the ordinary use of the word "cause," pointed out above, make it unlikely that the Libertarian will be persuaded by one who puts the matter in this way.

There is, as we have seen, a tension between the idea of "acting out of one's own free will" and "being caused to do something." It is therefore important to note that there may be a sense of "cause" which is stronger than that of mere predictability, and in which it is true to say that actions are caused, but not that persons are caused to do them. I shall be arguing shortly that there is such a sense, and that in this new sense volitions are, at least on occasion, the causes of actions. That causation in this further sense does not imply compulsion is indicated by its departure in grammar from the form "thing (or person) impinging on things (or persons) bringing about a change, etc."

But the Hume–Mill substitution of predictability for causation raises problems of its own, problems which in one way or another will be with us throughout the remainder of this paper. The crucial issue concerns the conceptual framework in which (or, as it used to be put, the level of explanation at which) the predictability is supposed to obtain. I have distinguished in a number of papers between what I call the "manifest image" and the "scientific image" of man-in-the-world.¹

Roughly, the manifest image corresponds to the world as conceived by P. F. Strawson — roughly it is the world as we know it to be in ordinary experience, supplemented by such inductive procedures as remain within the framework. The manifest image is, in particular, a framework in which the distinctive features of persons are conceptually irreducible to features of nonpersons, e.g. animals and merely material things. The scientific image, on the other hand, is man-in-the-world as we anticipate he would be conceived by a unified scientific account, which makes use of the familiar techniques of theory construction. The scientific image, although methodologically rooted in the manifest image, freely transcends the conceptual framework of the latter, introducing new concepts, as it is said, by "postulation," rather than by explicit definition, however widely construed. To articulate the philosophical tensions aroused by "scientific determinism," let us suppose that the scientific image contains a picture of man as part and parcel of a deterministic order. To make our thought-experiment as forceful as possible, let us suppose that, sooner or later, quantum phenomena will be found to have a deterministic substructure. Only by pressing this assumption can the irrelevance of quantum indeterminacy to the problem of free will be made manifest.

An indefinite amount of time could be spent in giving these two images of man-in-the-world a higher polish. I think however, that the above remarks suffice to mobilize a useful conception of the contrast I have in mind. The question I want to raise concerns the force of the term "predictable" in these two radically different conceptual frameworks. Thus we have supposed it to be a framework principle of the scientific image that every episode, including the scientific counterparts of human thoughts and actions, is predictable. Is it, correspondingly, a framework principle of the manifest image that all human actions be predictable? Could it perhaps be a framework principle of the manifest image that not all actions are predictable, although the very same actions that are "manifestly" unpredictable are, as projected in the scientific image, in principle predictable? And, if so, would we have to say that one or the other image, no matter which, gives a false account of what there really is?

If we now turn our attention to the manifest image, and examine the use of the term "predictable" in connection with persons and what they do, a number of points stand out quite clearly — provided, that is, that we are careful to avoid mixing in elements from the scientific image. To say of a person that his actions are predictable is not always a compliment. Even a person who can be counted on to do what is right is marked down a little when it is said that one can predict exactly what he will do. For to say this implies that he meets situations in routine ways, never thinking things through afresh or gaining new insight.

To be predictable, in this image, means that a person's actions are habitual, inferable by inductive reasoning based on observation of his past behavior. For an action to be predictable is for it to be an expression of character. It is therefore essential to note that, however predictable a person may become, not all of his actions can be expressions of character. Actions form character as well as express it, and the idea that actions which, in one respect, form character must, in another respect, be expressions of character can be traced to a confusion of the concept of the nature of a person (which concept belongs to the scientific image) with the concept of character. Even within the manifest image, of course, things have natures. The natures of material things are their abilities and predictabilities. The "realm of nature" consists traditionally of those things the observable behavior of which is either predictable, even if only "for the most part," or unintelligible because random. Their intelligibility is a matter of dispositions and propensities working themselves out and being called into play.²

In the post-renaissance period, there began that blurring of the distinction between the manifest and the incipient scientific image that has been, ever since, a source of philosophical confusion. The combination of the failure to draw a clear distinction between inductive generalization and theory construction with an increasing appreciation of the power of scientific thought, led to an exaggerated conception of the place of predictability within the manifest framework of perceptible things. And since, whatever else persons may be, they are perceptible things, the modern form of the problem of free will began to take shape.

It is therefore important to realize that, even with respect to merely material things, the manifest image is not able, out of its own resources, to generate a deterministic picture. A deterministic picture arises at best indirectly, by the correlation of perceptible things with systems of imperceptible scientific objects, which are metaphorically said to be "in" them.

To explain what an observable thing does by reference to theoretical processes that are taking place 'within' it is a radically different sort of thing from explaining the same behavior in terms of observable antecedent states.

A parallel, I believe, can be drawn between the above two modes of explanation and two modes of explaining the observable behavior of persons: (a) in terms of other observable behavior; (b) in terms of inner mental states. From this point of view, the explanation of behavior in terms of character would be analogous to explaining the observable behavior of material things by means of inductive generalizations. And when what a person does is not in this sense predictable — i.e. not an expression of "second nature" or character — it would nevertheless not be an "unintelligible" episode, as would be true if it were the behavior of a merely material thing, which could not have been predicted without appealing to theoretical considerations. The role of inner episodes in the manifest image can be compared to that of theoretical entities in the scientific image. They are, however, elements of an autonomous framework — not a speculative extension of microphysics — which carries the imprint of the specifically human observable behavior they are designed to explain.³

Thus, whereas the inductively unexplainable behavior of a merely material thing would be said to be unintelligible, a matter of chance, an inductively unexplainable action of a person — i.e. one which could not be explained in terms of character — can be intelligible in terms of being capable of explanation with reference to the practical reasoning and, ultimately, the volition of which it is the expression.⁴ Needless to say, character defined in terms of dispositions and propensities pertaining to overt behavior will have its counterpart in the framework of mental episodes, just as causal properties operationally defined in the observation framework have their counterparts in the theoretical framework which explains them. Suppose it is granted that, in the manifest image, actions which are not intelligible in terms of character can nevertheless be intelligible in terms of the practical reasoning which is its cause.⁵ But what, it may be asked, of this reasoning itself? Must not the occurrence of those inner episodes that explain the behavior of a rational being have a kind of intelligibility? And must not this intelligibility be a matter of predictability? The answer to the first question is, of course, yes. But to the second it is no! The intelligibility of thoughts is no more a matter of predictability than is the intelligibility of moves in games of chess — and for essentially the same reason.

I have been arguing that, in the manifest image, not everything that even a routine person does is predictable in the sense of being an expression of character, and that its intelligibility does not require predictability in this sense. I want now to make the stronger point that when, in ordinary discourse, we speak of predicting what a person will do, we have in mind what I referred to above as epistemic predictability. I want therefore to point out that, given that this is the sense of predictability involved, it is indeed a framework principle of the manifest image that the behavior of rational beings cannot be supposed to be universally predictable. This point transcends the more elementary one that acquiring a character presupposes actions which are not themselves expressions of character. For to be a rational being is to be a being who is capable of action that is not in character, and hence cannot be predicted within the framework of the manifest image.

But might not all human action be predictable if no holds are barred — if, that is, we take into account its projection in the scientific image? And if so, would this predictability be compatible with any genuine sense of individual responsibility? (That the predictability in question would have to be logical rather than epistemic is clear.) But, before we take up these questions, it will be helpful to introduce some concepts pertaining to voluntary action and put them to use in defining additional dimensions of the problem of free will.

1.