It sometimes happens that some metaphysical commitment, though logically consistent in a strict sense with competing, broad world views is, nevertheless, more plausible and at home in one rival compared with the other. Belief in life after death is a case in point. One could be a theist and consistently deny life after death, and one could follow C. J. Ducasse and accept both atheism and life after death. Still, the reality of life after death is not equally at home in a theistic vs. atheistic world view as most philosophers and theologians have recognized. I think the same sort of situation obtains regarding acceptance of libertarian agency against the backdrop of the rival world views of scientific naturalism and theism. In what follows, I shall not offer a general defense of this claim. Rather, I wish to focus on one aspect of it and show that libertarian freedom and agency are not plausible or at home given a prior commitment to scientific naturalism as it has come to be widely understood.

Most philosophers are agreed that libertarian freedom and a theory of agency it entails are incompatible with a generally accepted depiction of naturalism. Thus, Roderick Chisholm claims that “…in one very strict sense of the terms, there can be no science of man” (Chisholm 1989, 14). Along similar lines, John Searle says that “our conception of physical reality simply does not allow for radical [libertarian] freedom” (Searle 1984, 98). And if moral (and intellectual) responsibility has such freedom as a necessary condition, then reconciling the natural and ethical perspectives is problematic. In what may be the best naturalist attempt to accomplish such a reconciliation, John Bishop frankly admits that “the idea of a responsible agent, with the ‘originative’ ability to initiate events in the natural world, does not sit easily with the idea of [an agent as] a natural organism …. Our scientific understanding of human behavior seems to be in tension with a presupposition of the ethical stance we adopt toward it” (Bishop 1989, 1).

While most philosophers agree that libertarian agency and naturalism are incompatible, few attempts have been offered to spell out in some detail just why this is the case. My purpose in this article is to fill this gap in the literature by expanding on and clarifying the connection between naturalism as it is widely understood today and the rejection of libertarian agency. Due to space limitations, my sketch of naturalism will be a survey of naturalism as a whole viewpoint rather than a detailed analysis of a small set of features of the position. I think such a survey is needed in this context for the following reason: In the absence of an overall picture of the main components of the naturalist perspective, as well as the connections among those components, it is difficult to sense the force of a cumulative case against the viability of libertarian agency for the naturalist. If we keep before us just what naturalism is as a whole system of thought, it will be easier to appreciate why one cannot simply adjust libertarian agency to make it compatible with naturalism or vice versa. As an illustration of this last point, I will close with a brief analysis of a recent attempt by Randolph Clarke to work out aversion of libertarian agency that is acceptable to those philosophers who have taken the naturalistic turn (Clarke 1993). My purpose in considering Clarke is illustrative only, and I shall not attempt a detailed critique of his position in the short space given to my analysis of his approach to agency and naturalism. But by briefly considering a specific example of an attempt at spelling out a naturalist version of libertarian agency, I hope to show how the considerations developed in this article constitute the crucial desiderata a philosopher must address before she can claim to have worked out an adequate naturalist approach to libertarian agency.

A Sketch of Libertarian Agency

Let us use the term “libertarian agency” to stand for the type of agency that constitutes a necessary condition for libertarian freedom. I cannot attempt a detailed analysis of libertarian agency here. Fortunately, for my purposes it will be adequate to state the basic ideas contained in a theory of libertarian agency. Person P exercises libertarian agency and freely does some intentional act e just in case

1. P is a substance that has the active power to bring about e;
2. P exerted power as a first mover (an “originator”) to bring about e;
3. P had the categorical ability to refrain from exerting power to bring about e;
4. P acted for the sake of reasons which serve as the final cause or teleological goal for which P acted.

Taken alone, 1-3 state necessary and sufficient conditions for a pure voluntary act. Propositions 1-4 state necessary and sufficient conditions for an intentional act, i.e., a voluntary act done for a reason.

By “substance” I mean a member of a natural kind, an essentially characterized particular that sustains absolute sameness through (accidental) change and that possesses a primitive unity of parts, properties, and capacities/powers at a time. This strong view of substance may not be a necessary condition for libertarian agency, but it seems to be the most reasonable metaphysical analysis of libertarian agents, especially when compared to the main naturalist rivals, since the former depicts human beings in such a way as to affirm three features crucial to what it is to be a libertarian agent (cf. Moreland and Wallace, 1995; Moreland, 1995): 1) libertarian agency is possible only if there is a real distinction between the capacity to act or refrain from acting and the agent that possesses those capacities, and this is precisely what the classic doctrine of substance implies; 2) the type of unity present among the various capacities possessed by an agent is the type of unity (i.e., a diversity of capacities within an ontologically prior whole) that is entailed by the classic Aristotelian notion of substance; 3) typical free acts take time and include sub-acts as parts, and an enduring agent is what gives unity to such acts by being the same self who is present at the beginning of the action as intentional agent who originates motion, during the act as teleological guider of means to ends, and at the end as responsible actor.

The main naturalist rivals to the classic substance view of organic wholes like human beings are three: the Lockean bare substratum view, some form of bundle theory, and the property-thing position. The bare substratum view pictures agents as simple, bare I’s to which various properties are externally related. This view does allow for a distinction between the agent and its various properties, the former being a bare particular. But since bare substrata are simples with no internal capacities or powers, it is hard to see how bare agents can have the capacity to act or refrain from acting. As I am using the term, the bundle theory eschews mereology and an ontology of separable parts taken as concrete particulars in favor of an analysis of substances as a combination of properties and the bundling relation (Cf. Keith Campbell 1990). Moreover, when it comes to change, such bundles become series of events, especially on a property exemplification account of events, in which the bundles contain different combinations at different moments. It is widely recognized that bundle theories do not allow for absolute sameness through change. Further, a human being construed as a bundle just is a combination of properties, and not an ontologically prior whole that predicatively has properties. Thus, a bundle of properties does not have the metaphysical grounding necessary to exercise or refrain from exercising a capacity. Finally, by far the most popular naturalist view of living things is the property-thing position. A property-thing is a system of parts standing in external relations and possessing supervenient properties. Micro-parts are ontologically prior to the whole they constitute. In such a view, macro-properties like those mental features necessary for agency, are either epiphenomenal or else they (or more accurately, the events that contain them) can exhibit top-down, event causal feedback to subvenient states. Either way, libertarian agency is denied. Further, property-things do not sustain absolute sameness through change.

“Active power” is a conceptually primitive notion which has a sense that is ultimately understood ostensively in acts of first person introspective awareness of one’s own initiation of change. A characteristic mark of active power is the ability to initiate motion, to produce an act, e.g., when one endeavors or purposes to bring it about that one’s arm goes up, or to refrain from producing an act. Moreover, active power is a dual ability. So understood, it is impossible for an exercise of active power to be causally necessitated by prior events. A “first mover” is a substance which has active power. The notion of “categorical ability” in 3) has two important aspects to it. First, it expresses the type of ability possessed by a first mover that can exercise active power and, as such, it contrasts with the conditional ability employed by compatibilists. Second, categorical ability is a dual ability: if one has the ability to exert his power to do (or will to do) A, then one also has the ability to refrain from exerting his power to do (or to will to do) A. Finally, 4) expresses a view of reasons as irreducible, teleological goals for the sake of which a person acts. In general, we may characterize this by saying that person S F’d (e.g., went to the kitchen) in order to Y (e.g., get coffee or satisfy S’s desire for coffee). This characterization of action, according to 4), cannot be reduced to a causal theory of action that utilizes belief/desire event causation.

Two things should be mentioned about this definition of libertarian agency. First, there are two basic schools of thought regarding libertarian agency. Advocates of the first school hold to agent causation and, thus, believe that the first mover in 2 causes actions. Advocates of the second school accept a non-causal view of agency in which the actions of unmoved movers are uncaused events done for reasons as final causes. Either way, an unmoved mover is an agent that can act without sufficient causal conditions necessitating that the agent act-the agent is the absolute source of action. Second, libertarian agency theorists are divided about the role of reasons in an overall theory of agency. Non-causal theories of agency are clear in seeing reasons as final causes-teleological goals for the sake of which someone acts. Advocates of agent causation either accept this view of reasons or else they hold reasons to be necessary (efficient) causal conditions that, together with the agent’s own active exercise of power (and, perhaps, other conditions), cause the action. Therefore, some agent causationists would adjust 4) accordingly. It may be worth pointing out that I agree with those libertarians who see animals as self movers who exercise what is called originative spontaneity, in contrast to humans, who exercise liberty of will, the latter differing from the former by having reasons as causes (final or efficient necessary causal conditions).

Contemporary Naturalism

Just exactly what is contemporary naturalism (hereafter, simply naturalism)? As with any widely accepted ideology, there will be different nuances given to naturalism by different thinkers. But it is possible to give an accurate general characterization of naturalism as it is currently depicted by most of its friends and foes. Among other things, naturalism includes the ontological commitment: The spatiotemporal universe of physical entities that constitute the objects of natural scientific investigation is all there is. All particulars, properties, relations, and other entities should bear a relevant similarity to the paradigm case entities that characterize an ideal, completed physics. Naturalism involves three essential ingredients: an epistemic attitude, an etiological account of how all entities whatsoever came to be or why they change, and an ontological commitment.

The ordering of these three ingredients is important. There is a distinct tendency among naturalists for their epistemic attitude to serve as justification for the naturalist etiology which, in turn, helps to justify the naturalist’s ontological commitment. As John Post notes, “According to a number of influential philosophers, the sciences cumulatively tell us, in effect that everything can be accounted for in purely natural terms [the naturalist epistemic attitude]. The ability of the sciences to explain matters within their scope is already very great, and it is increasing all the time [an etiological account]. The world view this entails, according to many, is naturalism: Everything is a collection of entities of the sort the sciences are about, and all truth is determined ultimately by the truths about these basic scientific entities [an ontological commitment]” (Post 1991, 11). The above characterization of the naturalist ontology is adequate for my purposes, so in what follows, I shall focus on the other two components of contemporary scientific naturalism.

1. The Naturalist Epistemic Attitude

As is the case with much of modern philosophy, naturalism first and foremost is an expression of an epistemic posture, specifically, a posture called scientism. In the early 1960s, Wilfred Sellars expressed this posture when he said that “in the dimension of describing and explaining the world, science is the measure of all things, of what is that it is, and of what is not that it is not” (Sellars 1963, 173). Steven Wagner and Richard Warner claim that naturalism is “the view that only natural science deserves full and unqualified credence” (Wagner and Warner 1993, 1). Contemporary naturalists embrace either weak or strong scientism. According to the former, nonscientific fields are not worthless nor do they offer no intellectual results, but they are vastly inferior to science in their epistemic standing and do not merit full credence. According to the latter, unqualified cognitive value resides in science and in nothing else. Either way, naturalists are extremely skeptical of any claims about reality that are not justified by scientific methodology, explanation, and the like.

Naturalists believe that they are justified in this posture because of the success of science vis-à-vis other fields of inquiry. Many naturalists are also guided by belief in the unity of science. Roy Bhaskar asserts that “naturalism may be defined as the thesis that there is (or can be) an essential unity of method between the natural and the social sciences” (Bhaskar 1979, 3). And as John Searle notes (though this is not his view), since for most naturalists science exhausts what we can know, then belief in the unity of science turns out to be a belief in the unity of all knowledge because it is scientific knowledge:

Every fact in the universe is in principle knowable and understandable by human investigators. Because reality is physical, and because science concerns the investigation of physical reality, and because there are no limits on what we can know of physical reality, it follows that all facts are knowable and understandable by us (Searle 1992, 11).

For the naturalist, the preeminence and exhaustive nature of scientific knowledge entail that the only explanations that count are scientific explanations. Whatever exists or takes place in the world is either a brute fact or else it is susceptible to explanation by natural scientific methods and there is nothing which lies in principle beyond the scope of scientific explanation.

We have seen that scientism is the core epistemic posture of the contemporary naturalist. From this core commitment, at least four philosophical theses follow that in one way or another elaborate the epistemic and methodological constraints for philosophy that are part of taking the naturalistic turn. First, there is no such thing as first philosophy. According to David Papineau, there is a continuity between philosophy and natural science:

… the task of the philosophers is to bring coherence and order to the total set of assumptions we use to explain the natural world. The question at issue is whether all philosophical theorizing is of this kind. Naturalists will say that it is. Those with a more traditional attitude to philosophy will disagree. These traditionalists will allow, of course, that some philosophical problems, problems in applied philosophy, as it were, will fit the above account. But they will insist that when we turn to ‘first philosophy’, to the investigation of such fundamental categories as thought and knowledge, then philosophy must proceed independently of science. Naturalists will respond that there is no reason to place first philosophy outside of science (Papineau 1993, 3

Among other things, this means that naturalized and evolutionary epistemology will be what naturalists accept since issues in epistemology (e.g., the nature of knowledge, justification, warrant) will be framed and analyzed in terms of our best empirical scientific theories about perception, belief formation, and so forth.

A second, and closely related thesis results from the fact that “the philosopher who wants to regard human beings and mental phenomena as part of the natural order [must] explain intentional relations in naturalistic terms” (Stalnaker 1984, 6). The naturalist will hold to an externalist theory of knowledge or justification (or warrant). This is true for two main reasons, one positive and one negative. The positive reason is that “A scientific or naturalistic account of [human beings and their mental states] must be a causal account” (Post 1991, 121). And while Alvin Plantinga has developed a distinctively theistic externalist theory (Plantinga 1993a, 1993b), most versions of externalism are naturalistic. Naturalistic externalist theories in epistemology either implicitly (e.g., reliabilist theories) or explicitly (e.g., causal accounts) center on the notion of causality. The negative reason is this: the central notion of “internal” for the internalist is an irreducibly mental one whose analysis requires reference to such things as being a self-presenting property, being a mode of conscious, being directly present to the cognizer’s awareness, cognitive accessibility, being internal to one’s point of view, first person introspection, etc. Note that all these notions are mental. Moreover, they are irreducible if the perspective is to remain an internalist one because if these are reduced to (or replaced by) physicalist (causal) notions, then what is distinctive to internalism will fall out and the view will collapse into externalism. Why? Because neither the properties just mentioned nor the way that they are internal to knowing and believing subjects (e.g., by being self-presenting, being available to private, first person access) are parts of the ontology of physics. Internalist properties and intentional relations, as these actually function in internalist epistemological theories, are just not natural, physical, causal entities.

Third, naturalists must either eliminate the first person point of view or else reduce it to the third person perspective. Speaking of the physicalist conception of objective reality, Thomas Nagel observes that if “one starts from the objective side, the problem is how to accommodate, in a world that simply exists and has no perspectival center, any of the following things: (a) oneself; (b) one’s point of view; (c) the point of view of other selves, similar and dissimilar; and (d) the objects of various types of judgments that seem to emanate from these perspectives” (Nagel 1986, 27). Howard Robinson put his finger on the problem of the first person perspective for the naturalist when he noted that

The idea that science captures everything, except the centre of everyone’s universe, his own consciousness, makes a laughingstock of its claim to present a plausible world view. If science cannot encompass the subjective then subjectivity becomes a door through which mystical, irrational and religious notions can enter and reassert themselves against the modern metaphysic of scientific realism (Robinson 1982, 2; cf. Searle 1992, 10).

Because reality is objective, says the naturalist, the best way to study the mind is to adopt a third person perspective. Science is objective (in this third person sense) because, for the naturalist, reality itself is objective. Moreover, a complete, physical description of the world will only need to utilize third person descriptions. This is because physical facts are able to be captured entirely from a third person point of view without reference to any first person perspective.

Finally, the naturalist will be extremely skeptical of introspection, of beliefs that receive their justification from common sense (especially if they are not beliefs that can also be justified from science), or of philosophically justified entities that are not “at home” in the naturalist world view. In this vein, D. M. Armstrong wrote that “I suppose that if the principles involved [in analyzing the single all-embracing spatio-temporal system which is reality] were completely different from the current principles of physics, in particular if they involved appeal to mental entities, such as purposes, we might then count the analysis as a falsification of Naturalism” (Armstrong 1978a, 262).

We have looked at several philosophical expressions of different aspects of the epistemic attitude that constitutes naturalism. Let us now turn to an overview of the naturalist’s view of how things came to be.

2. The Naturalist Grand Story

The naturalist has an account of how all things whatever came to be. We can call this account the Grand Story. The details of the Grand Story need not concern us here. Suffice it to say that some version of the big bang (e.g. standard or inflationary models) is the most reasonable view currently available. On this view, all of reality-space, time, and matter-came from the original “creation” event and the various galaxies, stars, and other heavenly bodies eventually developed as the expanding universe went through various stages. On at least one of those heavenly bodies-earth-some sort of pre-biotic soup scenario explains how living things came into being from non-living chemicals. And the processes of evolution, understood in either neo-Darwinian or punctuated equilibrium terms, gave rise to all the life forms we see including human beings. Thus, all organism and their parts exist and are what they are because they contributed to (or at least did not hinder) the struggle for reproductive advantage. More specifically, because they contributed to the tasks of feeding, fighting, fleeing, and reproducing.

 There are several important things to note about the Grand Story. First, it is an expression of a naturalist version of philosophical monism according to which everything that exists or happens in the world is susceptible to explanations by natural scientific methods. This means that whatever exists or happens in the world is natural in this sense. Prima facie, the most consistent way to understand naturalism in this regard is to see it as entailing some version of strict physicalism: everything that exists is fundamentally matter, most likely, elementary particles (whether taken as points of potentiality, centers of mass/energy, or units of spatially extended stuff/waves), organized in various ways according to the laws of nature. By keeping track of these particles and their physical traits we are keeping track of everything that exists. No non-physical entities exist, including emergent ones (and, for some, including abstract objects). This constitutes a strict sense of physicalism.

Howard Robinson points out that, historically, materialism was the view that the only substances that exist are material ones but that a duality of properties and abstract objects were allowed (Robinson 1993, 1-3). Today, says Robinson, physicalists agree that whatever exists is physical, but they disagree about what “physical” designates: 1) whatever is exhaustively described in the language of physics and chemistry; 2) extend sense 1 to include sciences like biology; 3) extend these to include common sense (e.g. secondary qualities). In my view, two things are at issue here: adopting a sense of “physical” most consistent with the naturalist epistemic attitude (e.g., the unity of science) and accounting for both the existence and emergence of the properties in senses 2 and 3 within the constraints of the naturalist etiology. It is not enough simply to point to or describe a hierarchy of part/whole systems and their so-called emergent properties because without a naturalist explanation of their existence and origin, it is question-begging to announce that such emergent entities (and the various relations they sustain to lower level “systems”) are natural. Moreover, I have argued elsewhere that supervenient physicalism should not be taken as an option for a contemporary naturalist (Moreland 1998). Thus, strict physicalism is the most consistent option for a naturalist, especially in light of the naturalist Grand Story. Further, the naturalist notion of matter is passive. Matter is inert, it cannot exert its own causal powers or choose to do something, but rather, it does what it has to do given the laws of nature (either deterministic or probabilistic) and prior causal conditions. This is true irrespective of what we decide about the “ultimate” nature of matter, e.g. as a corpuscle of stuff, as a point field of force, or whatever. It is also true regardless of whether we take a chunk of matter to “act” on another chuck of matter merely by means of mechanical pushes and pulls or whether we attribute various forces to a chunk of matter. One’s decisions about these scientific issues are irrelevant to the question about whether or not matter is passive in a naturalist construal due to what it means to say that matter is passive. As we saw earlier, something is active only if it has power it can exert as a self mover (Cf. Rowel 991, chs. 2,4). Among other things, this means that active agents exercise spontaneous agency, e.g., agent causation. For the naturalist, matter is not like that. A unit of matter only “acts” because it has been acted upon. As Papineau says

I take it that physics, unlike the other special sciences, is complete, in the sense that all physical events are determined, or have their chances determined, by prior physical events according to physical laws. In other words, we never need to look beyond the realm of the physical in order to identify a set of antecedents which fixes the chances of subsequent physical occurrence. A purely physical specification, plus physical laws, will always suffice to tell us what is physically going to happen, insofar as that can be foretold at all (Papineau 1993, 16).

Thus, event causation is the view of causality for the naturalist: all events, whether they be alterations or cases of coming-to-be, are a result of prior events combined with either deterministic or probabilistic law. In general, event x is a cause of event y only if there is some law of nature under which x and y can be subsumed. Further, the most consistent naturalist view is to hold that the physical is causally closed and that there are no “gaps” in the causal fabric to be filled by causes at so-called higher, emergent levels of description. In this regard Jaegwon Kim says “a physicalist must, it seems, accept some form of the principle that the physical domain is causally closed-that if a physical phenomenon is causally explainable, it must have an explanation within the physical domain” (Kim 1993, 21; Cf. Kim 1995, 22633). But to the degree that a naturalist allows for such higher level causality, it will be viewed along the lines of feedback mechanisms and such cases will still conform to event causation. It would seem, then, that the most reasonable view for naturalists to take is to commit themselves to at least what is called causal reduction: the existence and causal powers of “reduced” macro entities are entirely explainable in terms of the causal powers of the “reducing” micro entities (e.g. the resistance to penetration for solid objects is entirely explainable in terms of the structure and movements of molecules or atoms).

Second, a machine metaphor is used by naturalists to explain living organisms. This follows from the two key elements of the Grand Story: the atomic theory of matter (and the rejection of any form of vitalism) and evolutionary biology (where macro-features-phenotypes-are explained by causal mechanisms at the micro-level-genotypes-and in terms of so-called functional explanations given in light of the constraints of reproductive advantage). This implies two things about living creatures. To begin with, they are not genuine substances understood, in the classic sense, as essentially characterized particulars 1) whose parts stand in internal relations with each other; 2) which sustain absolute sameness through change; and 3) which have a nature possessed by all members of their natural kinds. Darwin’s theory of evolution has made belief in, e.g. human substances with human natures, though logically possible, nevertheless, quite implausible. As E. Mayr has said: 

The concepts of unchanging essences and of complete discontinuities between every eidos (type) and all others make genuine evolutionary thinking impossible. I agree with those who claim that the essentialist philosophies of Aristotle and Plato are incompatible with evolutionary thinking (Mayr 1970, 4).

This belief has, in turn, led thinkers like David Hull to make the following observation:

The implications of moving species from the metaphysical category that can appropriately be characterized in terms of “natures” to a category for which such characterizations are inappropriate are extensive and fundamental. If species evolve in anything like the way that Darwin thought they did, then they cannot possibly have the sort of natures that traditional philosophers claimed they did. If species in general lack natures, then so does Homo sapiens as a biological species. If Homo sapiens lacks a nature, then no reference to biology can be made to support one’s claims about “human nature.” Perhaps all people are “persons,” share the same “personhood,” etc., but such claims must be explicated and defended with no reference to biology. Because so many moral, ethical, and political theories depend on some notion or other of human nature, Darwin’s theory brought into question all these theories. The implications are not entailments. One can always dissociate “Homo sapiens” from “human being,” but the result is a much less plausible position (Hull 1989, 74-75).

Thus, living organisms are not genuine substances for the naturalist. Rather, they are property-things. I mean by a property-thing an ordered aggregate, a set of parts put into external relations by some ordering principle (e.g., a law of nature) to form a whole. John Searle claims that “systems are collections of particles where the spatiotemporal boundaries of the system are set by causal relations… Babies, elephants, and mountain ranges are examples of systems” (Searle 1992, 86-87). I mean by a property-thing what Searle calls a system. The machine metaphor implies a second feature of living organisms: the functional explanations mentioned above are such that teleology is abandoned in a literal sense and efficient and material causes are used to explain different aspects of living creatures (as well as all other entities). For the naturalist, functional language is capable of a reduction so as to remove expressions of teleology. (Cf. Nissen 1993; Papineau 1993, 44-51). Consider the following two propositions.

(1) The function of X is Z.
(2) X does A in order to Z.

Naturalists will offer some version of an aetiological account of teleological notions like design, purpose, and function and will reduce (1) or (2) to either (3) or (3′):

(3) X was a cause of Z in the past and its having been a cause of Z in the past causes X to be there now.
(3′) X has the function of doing Z if and only if item X is now present as a result of causing Z.

A third and final point about the naturalist Grand Story is this. ‘While some naturalists eschew questions about the nature of existence itself (in which case they usually assert that to exist is merely to be a spatio-temporal physical particular that is part of the Grand Story), other naturalists have formulated a definition of existence based on naturalism and consistent with the Grand Story. Thus, Bruce Anne defines a exists as “a belongs to the space-time-causal system that is our world. Our world is, again, that system of (roughly) causally related objects ….” (Aune 1985, 35). Along similar lines, D. M. Armstrong says that for any entities, the following question settles the issue of whether or not those entities can be said to exist: “Are these entities, or are they not, capable of action upon the spatio-temporal system? Do these entities, or do they not, act in nature?” (Armstrong 1978a, 263; cf. 1978b, 126-35). Daniel Dennett claims that when we are trying to find out whether or not some entity like the self exists, what we must do is locate the entity within the causal fabric (Dennett 1984, 76). Keith Campbell applies the same reasoning to the question of the existence of emergent entities like social characteristics by claiming that the test of their existence turns on their ability to exhibit independent causality because “power has been recognized as the mark of being” (Campbell 1990, 172). Finally, Jaegwon Kim says “Causal powers and reality go hand in hand. To render mental events causally impotent is as good as banishing them from our ontology” (Kim 1993, 23). Again, the notion of action used in these statements is event causation.

Before we consider reasons why libertarian agency is not an option for a contemporary naturalist, I want to draw out one implication from what we have learned about contemporary naturalism. For someone to be a consistent naturalist, one is entitled to claim that some entity x is “at home” in a naturalist world view, as John Bishop puts it, just in case x 1) fits solely within a naturalist ontology (i.e. it bears a relevant resemblance to other-especially paradigm case natural entities in its parts, properties, relations, and behavior); 2) can, at least in principle, be given a naturalist etiological explanation in keeping with the naturalist epistemic attitude.

Why Libertarian Agency is Not an Option for the Naturalism

In light of what we have seen about libertarian agency and naturalism, we are in a position to see why the two do not “sit easily” with each other, as John Bishop has put it. In my view, there are at least six reasons why libertarian agency is not compatible with naturalism. The force of these six reasons depends on the holistic characterization of naturalism above. In one way or another, each reason shows that there is some aspect of libertarian agency that is inconsistent with naturalism. One through five support the conclusion that libertarian agency entails something that is incompatible with naturalism. Point six focuses, not on the reality of libertarian agency itself, but on the fact that we at least have a concept of it and that many people have the conviction that we do, in fact, exercise it.

First, for those naturalists who are determinists about the world of macro objects, then libertarian agency is not possible because determinism is sufficient, but not necessary to disallow such agency. This is due to the categorical ability, the type of dual control, and the self moving active power that are components of libertarian agent theory. The issue of quantum indeterminacy is irrelevant here for three reasons. First, I am addressing this problem to those naturalists that are determinists and, in any case, quantum indeterminacy may be merely epistemological and not ontological if some sort of hidden variable theory is correct. Second, even if quantum indeterminacy is ontological at the micro level, determinism could still rule at the macro level. Moreover, there would be no guarantee that the statistical indeterminacy of micro events could be directed down a specific macro pathway by a mental act, e.g., of willing to raise one’s arm to vote. Such an act may well require causing a chain of events outside the bounds of causal potential set by micro level indeterminacy. Finally, indeterminacy is neither necessary nor sufficient for the type of control thought necessary by libertarians to ground freedom (see point 3 below).

Second, the notion of a substance acting as an unmoved mover by exerting active power, by endeavoring to bring it about that such and such happens is simply not something a naturalist can countenance. For the naturalist, physical causes are the only causes there are and they are events (or, perhaps, facts) that cause other events (or at least fix their chances) according to the laws of nature. If event x is the cause of event y, then there is a law of nature that subsumes x and y. However, it is precisely as originative exercises of active power that the actions of a first mover are not susceptible to such causal explanations, scientific or otherwise, and the initiative exercises of power by a substantial agent transcend the laws of nature because those laws (combined with prior events) are not sufficient to produce the act. Something “more” — and in this sense, transcendent — is needed. This is why Bishop was correct when he identified a self mover’s originative exercise of active power as a central problem for a naturalist theory of agency: “[t]he idea of a responsible agent, with the ‘originative’ ability to initiate events in the natural world, does not sit easily with the idea of [an agent as] a natural organism …. Our scientific understanding of human behavior seems to be in tension with a presupposition of the ethical stance we adopt toward it” (Bishop 1989, 1). According to Bishop, this problem is so severe for the naturalist that one cannot have it both ways. One must either abandon naturalism or libertarian agency.

Third, as I have already argued, a traditional substance view of the self is the best account of a human person if libertarian agency (for human persons) is to be possible. The traditional doctrine of substance includes the notions of absolute identity through change (the same self exists as the initiator of an action and as the teleological guide of the various stages of complex acts until the end is reached, each temporal part of a complex act extending through time stands to the other parts in internal relations), active causal capacities, and organisms as self movers. But we have already seen that naturalism denies the substance view of human beings. As naturalist William Provine admits, “Free will as it is traditionally conceived …. simply does not exist …. There is no way that the evolutionary process as it is currently conceived can produce a being that is truly free to make choices” (Johnson 1993, 127; cf. Dennett 1984, 74-100).

In this regard, John Bishop says that “…the problem of natural agency is an ontological problem — a problem about whether the existence of actions can be admitted within a natural scientific perspective …. [A]gent causal-relations do not belong to the ontology of the natural perspective. Naturalism does not essentially employ the concept of a causal relation whose first member is in the category of person or agent (or even, for that matter, in the broader category of continuant or ‘substance’). All natural causal relations have first members in the category of event or state of affairs” (Bishop 1989,40).

Bishop’s point reminds us that the real problem of agency for the naturalist is not the problem of determinism. Determinism is sufficient but not necessary to generate a problem of agency. The real problem is that naturalism cannot allow for the existence of libertarian agency irrespective of the determinism question. Among other things, this means that the existence of so-called top-down feedback causation is irrelevant to the problem of agency. In this regard, Dennis Senchuk has argued that strict physicalism is deterministic for ordinary macro objects, but he claims that emergent event dualism is not (Senchuk 1991). He argues that consciousness is a genuine emergent property of certain wholes and that it can cause things to happen in the world, e.g. my conscious experience of pain can cause me to say “ouch!” (more precisely, in my view, it can cause a saying-of-“ouch!” to happen in me). Moreover, he claims that a specific state of consciousness does not uniquely determine a specific behavior and this allows for a certain indeterminate flexibility between a given conscious state (e.g. a feeling of pain) and a behavioral outcome as the “goal” of that conscious state (e.g. shouting “Ouch!” or “That hurts!”).

Unfortunately, Senchuk’s proposal will not do the job of giving the freedom necessary for responsible agency if such freedom requires libertarian agency. At best, Senchuk’s views only offer the (weak) naturalist a compatibilist view of freedom and a causal theory of action because his claims depict behavior as being caused by mental event causation or as being indeterminate and uncaused altogether. But in any case, Senchuk does not really address the fundamental and prior problem of the substantial nature of the agent, a problem that Bishop acknowledges is a basic difficulty for the naturalist.

Fourth, the view of reasons in libertarian agency is incompatible with naturalism. For one thing, most libertarians accept the view that a reason is an intrinsic and irreducible mental content, i.e. a reason has propositional content which, in turn, has a number of features problematic for the naturalist: it is not located in space or time nor is the way it is “in” the mind a spatio-temporal, physical sense of “in,” it is not an entity with causal powers, it is not identical to anything (e.g., a sentence) that can be sensuously perceived, it need not be grasped by the mind of any person at all to exist, it is intrinsically intentional, and it can stand to other propositions in various logical and epistemic relations (Cf. Willard 1984, 180-81). John Bishop says that the naturalist theory of agency requires as a necessary condition a physicalist theory of mind and it is easy to see why thoughts or reasons would have to be part of that physicalist theory. Further, though I cannot develop the case here, it is arguable that there is such a thing as intellectual duty and responsibility which, in turn, requires a weak form of indirect doxastic voluntarism as a necessary condition. And many libertarians claim that deliberation itself makes sense only if we assume libertarian agency. Finally, while there is some debate about this, nevertheless, I think most naturalists agree that irreducible teleology/final causality are hard to square with naturalism and that a causal theory of action in terms of, say, a belief/desire psychology is the best way for a naturalist to go regarding the role of “reasons” in human action. The point here is not to argue that such naturalist accounts of teleology fail, though I believe that to be the case; rather, my point is that those accounts entail either hard determinism or compatibilism and, either way, libertarian agency is denied.

Fifth, libertarian agency and action violates the principle of the conservation of energy because such actions imply that, if we set aside the possibility of causal over-determination, there is a gap between the state of the brain (or body) prior to or at the time of the action and the brain (or body) state after the action is done (Cf. Larmer 1986). This is because on the libertarian view, no physical description (or mental description for that matter) of the person at time t1 just prior to the person freely raising his arm to vote is sufficient for the arm raising. The state of affairs obtaining at t2 (the arm’s being raised) is not smoothly continuous with the state of affairs at t1 (there is a causal gap between them) because the agent’s own spontaneous exercise of active power is one of the necessary causal conditions for the arm’s being raised. This violation of the principle of conservation is not a cheerful prospect for the naturalist and he or she must abandon libertarian agency to avoid this situation. The libertarian has another way out. He or she can distinguish a strong and weak form of the principle. The former states that energy can neither be created nor destroyed; the latter says that energy can neither be created nor destroyed in a closed system. The libertarian can go on to assert that in free acts, the “system” is open to the “intervention” or causal contribution of an agent that transcends the system, but obviously, such a move is not open to the naturalist.

Finally, I think the naturalist has difficulty explaining how, given the truth of naturalism, the concept of libertarian agency and the belief or introspective awareness that we have it arose in the first place. John Searle is one naturalist who raises this question (Searle 1984, 94-99). He queries that since libertarian freedom is an illusion, how is it that we seem unable to abandon the belief that such freedom is true? Moreover, he asks, if life consists merely in the passive reception of causal inputs that run their course all the way to outputs, why would we come up with the inclination to believe we are free? The point here is not just the problem of error, viz., of explaining how we could be so convinced of our agency from introspective awareness of our own acts, given that such agency is a chimera. This is, indeed, an important issue. But more fundamentally, where would the concept of libertarian agency come from in the first place? It is arguably the case that we have to be acquainted with certain states of affairs before we can imagine them or conceive of what they are like. This is even true of conceiving of a unicorn, which is impossible unless we have experienced the elements (being a horn, being a horse) that compose unicorns. As Papineau admits, “we can’t imagine experiences of a radically unfamiliar kind, like seeing colours at all, or echolocating, until we have actually had those experiences” (Papineau 1993, 108). The importance of experiencing sound before one can conceive what it is like to hear is behind the famous knowledge argument for dualism. Now if something like this is part of the correct account of what is necessary before we can imagine or conceive of something, then how did it come about that people widely conceive of libertarian agency and the fact that they exhibit it, if they have never experienced such agency?

Relatedly, consider the problem of where the notion of means and ends would come from on a naturalist view. According to the naturalist, reality is just one spatio-temporal causal network where causal chains unfold via deterministic or probabilistic laws and event causation. In such a picture, all you have is temporal (and spatial) succession. One event follows the other. But the concepts of means and ends are embedded in the broader conceptualization of teleology, intentional action, final causality. If these do not exist, then where did people get the very concept of means and ends and from whence comes the conviction that they are true? All Searle can say to this problem is that, somehow and mysteriously, evolution just gave us a form of consciousness with the (illusory) experience that we are free.

Dennett takes a different strategy (Dennett 1984, 131-52). He agrees that in the metaphysical sense of “possible,” determinism implies actualism — only the actual is possible, the only thing that can happen is what does happen. But, says Dennett, metaphysical notions of possibility (different possibilities are real, genuinely different potential states of affairs) should be abandoned by the naturalist in favor of the notion of epistemic possibility: given the limitations of what we know about such and such, for all we know either A or B could happen in that neither is inconsistent with what we know. Now Dennett claims that when we deliberate about different “possibilities” regarding our own future actions or when we anticipate different “possibilities” regarding the actions of others, epistemic possibility is the relevant sense of possibility involved.

I do not wish to examine Dennett’s position further. I do think that his view of possibility is the most reasonable one for the naturalist to adopt because the naturalist has only two options regarding the occurrence of an event: either is was determined to happen, in which case it was the only metaphysically possible outcome given the laws of nature and the prior state of the universe or else it was uncaused, indeterministic, and fortuitous, in which case it is not clear in what sense the occurrence of the event is natural. For present purposes I merely want to point out that it is not obvious to me that the epistemic conception of possibility is the one we utilize in deliberation or in anticipating the actions of others and, in any case, if Dennett is right about this it is far from easy to see how the more robust notion of metaphysical possibility along with the conviction that it is the one relevant to deliberation and anticipation arose in the first place.

Clarke’s Attempt to Reconcile Libertarian Agency and Naturalism

These, then, are the main reasons that libertarian agency has been eschewed by naturalists. However, in a recent article Randolf Clarke claims to offer an agent-causal account of free will that is compatible with naturalism (Clarke 1993). According to Clarke, his account takes the mystery out of agent causation and allows there to be, in Chisholm’s sense above, a complete science of man by locating human agents entirely within the natural, causal order and by showing how human acts can be subsumed under event causal laws of nature. For Clarke, the two main features of agent causation are 1) there is a genuine variety of things an agent can do and 2) the agent brings it about that she does one of these things. The first feature requires a rejection of determinism and the second can be secured by what Clarke calls the condition of causal production (CP):

When an agent acts with free will, her action is causally brought about by something that (a) is not itself causally brought about by anything over which she has no control, and that (b) is related to her in such a way that, in virtue of its causing her action, she determines which actions she performs.

Clarke goes on to claim that traditional agent causal theories fail for two reasons: First, they do not make clear how reasons enter into their account and what is required here is a view of reasons as states of agents acting as efficient event causes of actions. In light of what I have presented earlier, Clarke’s assertion here is clearly false for two reasons.

For one thing, some agent causation libertarians depict reasons as necessary, efficient causal conditions that, together with the agent’s own exercise of power, cause the action. Second, a libertarian view of agency does not require a view of reasons as efficient event causes. Noncausal views and some agent causationists take reasons to be teleological ends and Clark is simply mistaken in claiming that reasons are required to be efficient, event causes.

Second, Clarke says that traditional agent-causal theories fail to clarify what causation by an agent is supposed to be. Unfortunately, this claim is also false. To show this, let us assume a volitional theory of action, simply for the purposes of illustration, and consider the raising of one’s arm to vote. The raising of one’s arm is an event with a beginning and it is caused by another event-a volition. But the volition is an event with a beginning and it has a cause as well, namely, the agent. Now, what does the agent do to cause his volition? If the agent does something, is what he does itself an event and if so, does it need a cause? Let us side with the majority of philosophers and grant that this solution to the difficulty is inadequate: the agent causes an infinite hierarchy of events in causing his volition. ‘What other solutions are available? There are three which have been most widely recognized (cf. Rowe 1991, 30-40, 145-61):

AC I: The agent does not do anything to cause his volition. The volition is a basic act produced directly by the agent without exercising any power to produce it. The agent is simply the first relatum that stands in a primitive causal relation to the second relatum, the volitional event.

AC II: The agent does do something to cause his volition, namely, he exercises a power and an exercise of power is not an event at least in the sense that it is not a change within an agent. An exercise of power is simply the exertion of a self moving power or principle of self determination that is not itself a change undergone by the agent. In libertarian acts, agents are unmoved or first movers. They do not first undergo a change (an exercise of power) before they can cause a change (a volition). Rather, agents qua substances directly cause their volitions by virtue of possessing and exercising their power to do so.

AC III: It is broadly logically impossible for someone to be caused to agent-cause something else, e.g., a volition. So if we grant that an exercise of power is an event (i.e., a change within the agent), when we recognize that such an exercise just is the event of an agent directly agent-causing his volition (the exercise of power isn’t an event caused by the agent which, in turn, event causes the volition   loll), it becomes clear that it does not have an efficient cause because it cannot (though it may have a reason which serves as the final cause of the exercise of power).

My purpose here is not to defend any of these views, but to present them in order to rebut Clarke’s charge that libertarians have not clarified what causation by an agent is supposed to be. More could be said about AC I-III, but each of them currently enjoys acceptance by participants in the dialog about libertarian agency and each has been clarified sufficiently to render Clarke’s charge otiose.

Clarke’s own account allegedly solves both these problems (specifying the role of reasons and the nature of causation by an agent) that he claims are not adequately addressed by other libertarians. He begins by assuming that determinism is false and that probabilistic causality for a single event is true. For example, suppose a given event E has an objective probability of.6 that it occur now and .4 that E not occur. Now whichever act a person performs freely can still be one that is probabilistically caused by earlier events, especially the event of coming to have a reason for performing that act. The agent causes, say, E to occur instead of some other alternative; more specifically, the agent causes her performing E because of a certain ordering of reasons. Clarke is ambiguous and appears to equivocate about what it means for a state of having-a-reason-for-performing-E to cause the action. Prima facie, in some places he appears to say that the reason itself causes the action and, since he also says the agent causes the performing of the action, Clarke would appear to believe in causal overdetermination. However, in other places he says that the reason is a necessary causal condition and the agent cause is also a necessary causal condition. In a sense, the agent acts by ratifying one set of reasons and not another within the probabilistic set of alternatives open to the agent and without causing any detectable change in the probability of a set of similar acts other than what could be entirely predicted by probabilistic event causation without the agent cause. Finally, Clarke claims that the agent causal relation is identical to the event causal relation (agent causation differs from event causation by having an agent/person as the first relatum), it is an irreducible feature of the universe, and it is grounded in laws of nature which consist of second-order relations among universals.

Has Clarke reconciled agent causation with the natural order? No for the following reasons. First, he assumes but does not argue for the claim that the best way for reasons to figure into a libertarian theory of agency is to see them as efficient causes or causal conditions. But as we have seen, advocates of the non-causal theory of agency, along with some proponents of agent causation, would not accept this view of reasons as either philosophically adequate or as a proper description of libertarian agency. In fact, Clarke himself seems to equivocate between reasons as final and efficient causes. In one place he seems to equate the idea of acting on certain reasons and acting for certain reasons. The former is efficient causality and it is clearly the one he seems to be after. However, later in his article he appears to use the notion of acting for reasons in an irreducibly final causal way. He does this, for example, when he says that agents cause the complex event of acting for a particular ordering of reasons. Now such an ordering (e.g., of going to a lecture primarily in order to learn about the subject and secondarily in order to express friendship with the speaker) seems to imply a final end in terms of which actions and reasons are ordered as means or goals. As I have argued earlier, this type of teleology is not at home in a naturalist world view. In this vein, D. M. Armstrong wrote that “I suppose that if the principles involved [in analyzing the single all-embracing spatio-temporal system which is reality] were completely different from the current principles of physics, in particular if they involved appeal to mental entities, such as purposes, we might then count the analysis as a falsification of Naturalism” (Armstrong 1978a, 262). If I am correct about this, then Clarke needs to analyze acting for a reason in terms of efficient causality if his account is to remain within the strictures set by taking the naturalistic turn. However, in this case, Clarke’s account will be judged inadequate by libertarians who employ an irreducibly teleological account of the role of reasons in libertarian action. At the very least, Clarke begs an important question here and this inveighs against his claim to present an adequate naturalistic theory of libertarian agency.

Further, Clarke simply asserts, without any argument whatever, that a law of nature might exist to the effect that any individual who acts with the capacity of reflective practical reasoning acts freely. There are at least two problems with this claim. First, such a law fails to bear a relevant similarity to other laws or relations that constitute a consistent naturalist ontology. Most naturalists reject the idea of a causal relation as that relation is understood in Cartesian interactionism, because, among other things, such a relation is just not physical. It is not relevantly similar to other causal relations that are found in the hard sciences and, for this reason, it cannot be construed as a “natural” relation that fits easily into a naturalist ontology. Elsewhere, I have made the same claim for a supervenience relation between mental and physical entities. (Moreland 1998) Under Clarke’s description of them, how could such a law be considered a law of nature to a naturalist? How can reasons or the precise sort of ordering they exemplify in Clarke’s view of actions be considered natural entities in any serious sense of naturalism?

Second, how would such a law of nature come to be exemplified in the naturalist Grand Story? To appreciate this problem, consider Paul Churchland’s claim that a naturalist ought to reject the existence of both mental substances and properties:

The important point about the standard evolutionary story is that the human species and all of Its features are the wholly physical outcome of a purely physical process … If this is the correct account of our origins, I lien there seems neither need, nor room, to fit any nonphysical substances or properties into our theoretical account of ourselves. We are creatures of matter. And we should learn to live with that fact (Churchland 1984, 21).

Churchland puts his finger on two reasons the naturalist should opt for strong physicalism, there is neither need nor room for anything else. Regarding need, I take it he means that everything we need in order to explain the origin and workings of human beings can be supplied by physicalist causal explanations. Regarding room, entities do not come into existence ex nihilo nor do radically different kinds of entities emerge from purely physical components placed in some sort of complex arrangement. What comes from the physical by means of physical processes will also be physical. Now the same sort of problem arises in connection with Clarke’s assertion that a law of nature might exist to the effect that any individual who acts with the capacity of reflective practical reasoning acts freely. By parity of reason with Churchland’s argument, there seems to be neither need nor room for such a law to be exemplified in the naturalist Grand Story, at least if that story is to remain a strictly naturalist one. Most naturalists agree with Churchland and recognize that the naturalist Grand Story commits one to a view of the types of entities a naturalist can allow. At the very least, Clarke ought to offer some argument as to how his view of such laws can be harmonized with the naturalist Grand Story. Given this problem, he cannot just announce that these laws are “natural” and leave it at that.