Reasons, causes, and chance-incompatibilism Markus E. Schlosser, University College Dublin, markus.schlosser@ucd.ie Forthcoming in Philosophia This is the author's copy (which may differ from the final print version in minor details) Abstract Libertarianism appears to be incoherent, because free will appears to be incompatible with indeterminism. In support of this claim, van Inwagen offered an argument that is now known as the "rollback argument". In a recent reply, Lara Buchak has argued that the underlying thought experiment fails to support the first of two key premises. On her view, this points to an unexplored alternative in the free will debate, which she calls "chance-incompatibilism". I will argue that the rollback thought experiment does support the second key premise of the argument, and, more importantly, that libertarianism is committed to the first premise for independent reasons concerning the relationship between the normative and causal strength of the agent's reasons. The upshot will be that chance-incompatibilism is not a promising new alternative in the free will debate, and we will see that the debate around those issues can benefit from more attention to the role of the agent's reasons for action. 1. Introduction It has often been observed that libertarianism about free will appears to be incoherent, because free will appears to be incompatible with indeterminism: how could an agent have control over choices and actions that are undetermined and a matter of mere chance? One widely discussed version of this challenge is an argument by van Inwagen (2000), which is now known as the "rollback argument". In a recent reply, Lara Buchak (2013) has argued that the underlying thought experiment fails to support the conclusion of the argument, because it fails to support the claim that an undetermined action has a definite objective probability. On her view, the thought experiments leaves open an unexplored alternative for libertarians, which she calls "chance-incompatibilism" (more on this below). I will propose here a different version of the challenge that bypasses Buchak's response. First, I will point out that the rollback thought experiment does support one of the key premises of the rollback argument-the premise that an action cannot be performed with free will, if it has an objective probability. Then I will argue that libertarianism is committed to the 2 claim that undetermined actions have objective probabilities, because it is committed to the claim that the causal strength of an agent's reasons tends to reflect their normative strength. This argument does not rule out chance-incompatibilism, but we will see that it casts serious doubt on the suggestion that this view is a promising new alternative in the free will debate. Further, it will become clear that the debate around the rollback argument and about libertarianism, more generally, can benefit from more attention to the role of the agent's reasons and the relationship between their normative and causal strength. 2. Libertarianism and the rollback argument According to libertarianism, we have free will and having free will is incompatible with determinism. According to the most common versions of the view, free will requires that some of our choices are not causally determined by antecedent states and events, and it is commonly assumed that making a choice is itself an action. Throughout, I will assume that this is the correct construal of libertarianism. Libertarians argue that free will is incompatible with determinism, and they face the challenge that free will appears to be incompatible with indeterminism. One widely discussed version of this challenge is van Inwagen's (2000) rollback argument, which is based on the following thought experiment. Alice decided to tell the truth on a certain matter after considering both telling the truth and telling a lie. We assume that libertarianism is true and that Alice's choice was free and therefore undetermined. Suppose that after Alice made her choice, the entire universe was "rolled back", by God perhaps, to the moment before Alice decided to tell the truth, and then left to unfold again. Suppose that this happens a thousand times, and that after 726 reruns we observe that the ratio of the cases in which Alice tells the truth and the ones in which she lies converges on some definite number. Suppose, for instance, that the ratio converges on 0.5/0.5 (with Alice telling the truth in half of the cases and telling a lie in the others). Given this, we face the "inescapable impression", as van Inwagen says, that what happens in the 727th rerun will be a "matter of chance" in the "strictest sense imaginable" (van Inwagen 2000, p. 15). Van Inwagen goes on to ask: If she was faced with telling the truth and lying, and it was a mere matter of chance which of these things she did, how can we say that-and this is essential to the act's being free-she was able to tell the truth and able to lie? How could anyone be able to determine the outcome of a process when it is a matter of objective, ground-floor chance? (pp. 15–16) 3 Those questions are rhetorical, because the thought experiment is supposed to support the conclusion that Alice does not choose with free will. We obtain, according to van Inwagen, an "informal" and "intuitive" argument for the claim that free will is incompatible with indeterminism (p. 11).1 In her reply, Buchak (2013) has argued that the rollback argument fails to support a crucial premise. Following her discussion (p. 22), let us reconstruct the argument as follows: (1R) In the Alice scenario, which assumes indeterminism, the ratio of truth-telling to lying converges on some definite real number. (2R) The best explanation for this convergence is that truth-telling and lying have definite objective probabilities, at a time before Alice makes the choice. (3R) If a choice has a definite objective probability before it is made, then it cannot be made with free will. Therefore, Alice does not choose with free will. Buchak accepts premise 2R and she is happy to grant 3R. But she argues that the scenario itself provides no support whatsoever for the assumption that the ratio of truth-telling to lying will converge on some definite real number. Van Inwagen simply assumed this in his description of the case: As the number of "replays" increases, we observers shall-almost certainly-observe the ratio of the outcome "truth" to the outcome "lie" settling down to, converging on, some value. (2000, p. 14) Despite the qualification ("almost certainly"), van Inwagen thinks that it is safe to assume that the ratio converges on some real number. Buchak argues that nothing guarantees this-it is perfectly possible that the ratio never converges. The argument begs therefore the question against, what she calls, "chance-incompatibilism": the view that "an act cannot have been free at a time if its occurrence had a definite chance at that time" (p. 25). In particular, it remains 1 According to van Inwagen, the rollback argument shows, in particular, that agent-causal theories of agency cannot account for free will, and he concluded that "free will remains a mystery" (apparently under the assumption that rival event-causal and non-causal accounts are untenable as well). But it is now commonly recognized that the rollback argument raises a general challenge for libertarianism (Franklin 2011, Buchak 2013 Shabo 2014, for instance), and the argument is sometimes presented as a version of the so called "luck argument" against libertarianism (Franklin 2011, for instance). We will first consider the general challenge to libertarianism. In section 5, we will turn to the particular challenge to agent-causal libertarianism. 4 "open to chance-incompatibilists to deny that a free act has a definite objective chance of occurring before the agent exercises her free will" (p. 25). As far as I can see, Buchak is right about this.2 I will, in any case, assume here that she is right about this, because I want to shift the focus on two different points. The first concerns the role of the rollback scenario. Buchak's concern is whether or not the rollback scenario supports premise 1R, and she argues that it does not. But the scenario is also supposed to provide support for premise 3R. Consider the following passage from van Inwagen: If we knew beforehand that the objective, "ground-floor" probabilities of Alice's telling the truth and Alice's lying were both 0.5, then [...] we could only regard ourselves as fortunate when, in the event, she told the truth. But then how can we say that Alice's telling the truth was a free act? (2000, p. 15) Again, the question is rhetorical. Van Inwagen clearly thinks that the scenario supports the conclusion that her choice is not made with free will, and the claim that both truth-telling and lying have objective probabilities before she makes the choice serves as a premise here: if we knew the objective probabilities beforehand, it would seem to us that Alice is merely fortunate in case she decides to tell the truth. It would seem, in particular, that Alice does not have the kind of control that seems to be required for choosing with free will. Understood in this way, the rollback scenario is supposed to provide support for premise 3R: if a choice has a definite objective probability, then it cannot be made with free will. Of course, given Buchak's reply, we lack now an argument for premise 1R. This brings us to the second point. There is, as I will argue in the following two sections, good and independent reason to assume that open and undetermined alternatives have objective probabilities before the agent makes the choice. 3. Objective probabilities To begin with, let me distinguish between objective probabilities and definite objective probabilities. Objective probabilities are to be contrasted with subjective probabilities (or 2 According to Buchak, van Inwagen's reason for thinking that the convergence will occur is "clearly the law of large numbers, which says roughly that if we repeat an event with two possible outcomes many times over, the ratio of each outcome to the number of trials will, with increasing likelihood, tend to the (objective) probability of each outcome" (p. 23). Given this, the problem is that the law of large numbers just states what is in need of justification here. Now, van Inwagen does not explicitly mention the law of large numbers. But I am happy to accept Buchak's diagnosis, as I am happy, for present purposes, to reject the first premise with her. 5 degrees of belief). They can be characterized as mind-independent, metaphysically real, or grounded in facts of metaphysical chance (propensities or tendencies). Events that have an objective probability have a degree or magnitude: they are more or less likely to occur. Definite objective probabilities can be assigned a definite real number. This has both a metaphysical and an epistemological component. They have a definite degree or magnitude, which corresponds to a definite real number, and which we may or may not know. It seems possible that there are objective probabilities that are not definite in both the metaphysical and the epistemological sense. It is clearly possible that we cannot know the definite degree of a particular objective probability, and it seems also possible that there are objective probabilities that do not have a definite degree or magnitude. If probabilities are grounded in frequencies, for instance, then the non-definiteness of an objective probability may be grounded in the fact that the relevant sequence does not converge on a definite real number. Or, if there is such a thing as ontological vagueness, the non-definiteness of an objective probability may be a brute metaphysical fact (concerning tendencies or propensities with vague magnitudes, for instance). Non-definite objective probabilities have some degree or magnitude. Otherwise, they would not be probabilities (chances, tendencies, or propensities).3 This can be expressed in approximate numerical terms or in relative terms. For instance, the definite objective probability of Alice's truth-telling may be 0.5, 0.8, and so on. The nondefinite objective probability of Alice's truth-telling may be about 0.5 or 0.8; it may be about the same as the probability as Alice's lying; it may be significantly higher than the probability of Alice's lying; it may be somewhat lower; and so on. Given this, we can also distinguish between definite and non-definite probability raising. Of particular interest here is the influence of the reasons that an agent considers in deliberation. In an instance of definite probability raising, Alice's consideration of reasons may raise the probability of her truth-telling to 0.8. In instances of non-definite probability raising, we cannot assign a definite real number. In absolute terms, it may be that her reasons raise the probability of her truth-telling to about 0.8, for instance. Or, in relative terms, it may 3 Some may balk at the suggestion that there can be non-definite probabilities on the ground that probabilities are defined as real numbers (that satisfy the axioms of the probability calculus). But this definition is not mandatory, even if it is the standard in some areas of research. In the free will debate it is commonly assumed that probability can be interpreted metaphysically or objectively, and I share this assumption. Further, I assume that we need not reserve the term 'probability' for the assigned numbers, distinguished from the metaphysical tendencies or propensities, as the context makes it clear enough what is meant. If one thinks that there is still a problem, one may substitute 'chance', 'tendency', or 'propensity' for 'probability'. 6 be that her reasons raise the probability of her truth-telling significantly more than that of her telling a lie, and so on. All this may seem very controversial and it raises further questions, as far as the philosophy of probability is concerned. However, the point that I would like to make here is merely that the challenge to libertarianism does not depend on the assumption that the relevant objective probabilities are definite. Suppose that the objective probability of Alice's telling the truth is about 0.5, or suppose that it is about the same as the probability of her telling a lie. The fact that those probabilities are not definite does not undermine or weaken the force of the challenge in any way. Given that those probabilities are objective, absolutely nothing depends on the further question of whether or not they are definite. Further, nothing depends on the assumption that the probabilities are about 0.5 or about even. As both van Inwagen and Buchak pointed out, the argument works just as well if we assume that the relevant probabilities are 0.7 and 0.3, for instance, and it is plain that the argument works also just as well if we assume that the probabilities are about 0.7 and 0.3. Similarly, the argument has the same force if we assume merely that the objective probability of Alice's telling the truth is higher than that of her telling a lie, for instance.4 Given this, we do not have to find an argument in support of premise 1R in order to defend the challenge to libertarianism. Premise 1R claims that the ratio of truth-telling to lying converges on some definite real number. We do not need to establish this. All we need is good and independent reason to think that the alternatives have some objective probability before Alice makes the choice. Given this, we can modify the first and the third premise to obtain the following version of the argument, which I will call the chance argument (and for which we do not need the second premise): (1C) In the Alice scenario, which assumes indeterminism, both truth-telling and lying have an objective probability before Alice makes the choice. (3C) If a choice has an objective probability before it is made, then it cannot be made with free will. 4 It would seem very plausible to assume that such non-definite probabilities should remain within a certain range, partly because it seems that the agent's reasons should narrow the probabilities to a certain range. Note that this raises an apparent problem for chance-incompatibilism. The view denies that undetermined alternatives have an objective probability before the choice is made. This seems to be incompatible with the intuition that the agent's reasons should narrow the likelihoods with which certain alternatives may or may not be chosen. Unfortunately, Buchak (2013) does not address this. 7 Therefore, Alice does not choose with free will. This argument could easily be turned into a generalized chance argument for the claim that an agent does not choose with free will, if the choice has an objective probability before it is made. We will turn to the question of whether or not libertarianism is committed to 3C below in section 6. For now, note that if the rollback scenario supports 3R, it clearly supports 3C as well. As I have just argued, concerning the antecedents in 3R and 3C, it does not matter at all whether or not we assume that the probabilities in the Alice scenario are definite. All that matters is that they are objective and that we can make some assumptions about their absolute or relative magnitude. The most pressing question is, then, whether or not there is good reason to hold premise 1C. Why think that undetermined alternatives have an objective probability before the agent makes the choice? One might try and argue that the rollback scenario does support this weakened version of the first premise. But I will pursue a different line of argument here that sidesteps the issues and questions concerning frequency interpretations of objective probability. Discussions of the rollback argument have generally neglected the role of Alice's reasons. That is where good and independent support for the first premise can be found. 4. Reasons and causes According to all standard versions of libertarianism, an agent can have genuine free will only if the agent has the capacity for rational agency. In fact, this assumption is very widely shared in the free will debate at large. The reason for this is, very roughly, that it is widely assumed that only intentional actions can be genuinely free and that the nature of intentional action is to be explained in terms of what it is to act for reasons. On the most common version of this view, an agent acts for reasons if the action is based on mental states and events that rationalize the action (such as desires, beliefs, and intentions).5 Given this framework, and given that free choices are undetermined, it would not only be very plausible for libertarians to assume that the perceived normative strength of reasons should, generally and roughly, be reflected in the strength of their causal influence. It seems, rather, that libertarianism is committed to this view. If free agency presupposes the capacity 5 If one objects to the claim that reasons are mental attitudes, one may modify this to accommodate the view that reasons are the contents of the relevant mental attitudes (or what those content are about). Nothing of substance hangs on this issue for our purposes here. 8 for rational agency, then there should be some systematic and reliable connection between the normative and the causal strength of the agent's reasons. This connection need not be perfect. On many occasions, it may even be far from perfect. Given, however, the agent must have the capacity for rational agency, there must be some connection: it must be the case that the causal strength of the agent's reasons tends to reflect their perceived normative strength- perceived, that is, from the agent's point of view.6 What should the agent's reasons tend to influence? Generally and roughly, the agent's reasons should tend to influence the agent's practical deliberations, choices, and actions in a way that tends to reflect their perceived normative strength. Consider the following variation of the Alice scenario. Suppose that Alice judges that the reasons for truth-telling greatly outweigh the normative strength of the reasons for telling a lie, and suppose that she judges, therefore, that she should tell the truth. If Alice is rational, on this occasion, then the causal influence of her reasons mirrors their normative strength, such that the causal influence of her reasons for truth-telling is significantly stronger than the causal influence of her reasons for lying. Given that her choice is causally undetermined, her reasons for truth-telling do not determine her choice. Rather, they raise the objective probability of her choosing to tell the truth to a significantly higher degree than her reasons for lying raise the objective probability of her choosing to tell a lie. Given, further, that Alice's reasons influence her deliberation, they will exert their influence before she makes the choice. Nothing depends here on the assumption that Alice is rational on this particular occasion. To see this, consider a variation in which Alice decides contrary to her better judgment. Suppose now that Alice judges that she should tell a lie, perhaps for consequentialist reasons. Despite this, she is strongly inclined to tell the truth, perhaps due to her character and upbringing. Suppose that, after deliberation, she decides to tell the truth. We assume that the agent's reasons are mental states and events that provide the relevant rationalizing explanations from the agent's point of view. Reasons, so construed, may easily come into conflict with each other. In particular, an agent's evaluative judgment on what is best may not be in line with the agent's strongest desire or inclination. In the present case, Alice acts against what she judges to be her best normative reasons, but her action is nevertheless based on a motivating reason (her inclination to tell the truth). One may disagree 6 We do not need to concern ourselves here with the further question of whether the perceived normative strength of the agent's reasons reflects their actual or objective normative strength. 9 with this particular description of the case. But nothing of substance hangs on this. Everyone, I take it, can agree that the evaluative judgment and the desire have some influence on Alice's deliberation and choice. So, even if Alice acts irrationally, against her better judgment, we would assume that her reasons exert some influence before she makes the choice, during deliberation. This does not necessarily require the ascription of objective probabilities to the alternatives before the choice is made. But it is very difficult to see how one could construe the underlying metaphysics without the ascription of such probabilities. This is difficult to see, because it is difficult to see how else reasons could have an objectively or metaphysically real influence on undetermined choices and action. It seems, at least, that if the agent's reasons are to have a bearing on an undetermined alternative, they must have (or confer) the power to make it more or less likely that this alternative is being chosen. And that, it seems, is just to say that the agent's reasons must have the power to raise or lower the objective probabilities of alternatives, which means, in turn, that undetermined alternatives must have objective probabilities before they are chosen. I simply cannot think of any other way of how to construe the underlying metaphysics here (allowing, of course, for terminological variations). How else could one construe the influence of reasons over undetermined choices and actions in a way that can reflect the varying degrees in their normative strength? Now, some libertarians reject the view that reasons are causes. One might set this aside as a minority position, but we need not resort to this. No one, I take it, would deny that an agent's reasons should exert some kind of influence over the agent's deliberations, choices, and actions. For our purposes, nothing depends here on whether or not we construe this influence as causal (or event-causal). All that matters is that this influence is objective, or metaphysically real, and that it must come in degrees with absolute or relative strengths in order to have the tendency to reflect the perceived normative strengths of what the agent takes as reasons for action. As far as I know, all libertarians would agree with this: they would agree that reasons usually incline an agent to choose one action rather than another, that this influence comes in degrees, and that it usually influences the agent's deliberations before the choice is made.7 Again, this does not entail or require the ascription of objective probabilities. But it is, again, very difficult to see how one could construe the metaphysics of the influence of reasons over underdetermined alternatives without the ascription of objective probabilities. 7 O'Connor (2000), for instance, denies that reasons are causes, but he nevertheless maintains that "recognizing a reason to act induces or elevates an objective propensity of the agent to initiate the behavior" (p. 97). 10 It seems that reasons must have (or confer) the power to influence how likely it is for certain alternatives to be chosen. This seems to require the ascription of a power to raise or lower objective probabilities, which requires the ascription of objective probabilities, tout court. And if reasons have the power to influence choices by raising or lowering probabilities, it is clear that they should have (or confer) this power before the choice is made. This provides us, then, with a very good reason to assume that an agent's open and undetermined alternatives have objective probabilities before the agent makes the choice in question-it provides us with a good reason to endorse premise 1C. This reason is based on considerations concerning the connection between free and rational agency. It is entirely independent from the question of whether or not the relevant objective probabilities in sequential reruns of a particular case would converge on some definite real number, and it is entirely independent from the question of whether of not free will is compatible with determinism. A corollary of this is that it is not open to incompatibilists to deny that a free act has an objective chance of occurring before the agent exercises her free will. It may remain open to incompatibilists to deny that a free act has a definite objective chance of occurring before the agent exercises her free will, as Buchak has argued. But we can see now that this is an empty victory. Even chance-incompatibilism is subject to the chance argument, which has the same conclusion as the rollback argument. Let me stress that this argument for premise 1C does not depend on the assumption that the relevant objective probabilities are not definite. Indeed, the argument is perfectly compatible with the claim that non-definite objective probabilities (tendencies or propensities) are impossible.8 I assumed the possibility of non-definite probabilities in order to show that the challenge to libertarianism does not depend on the assumption that the relevant probabilities are definite. If one could show either that probabilities can be objective only if they are definite or that non-definite probabilities are impossible, then the offered argument for premise 1C would show that libertarianism is committed to definite objective probabilities. But this would not strengthen the challenge to libertarianism. As far as the challenge to libertarianism is concerned, it simply does not matter whether the objective 8 Note, once more, that one may substitute 'objective tendency' or 'objective propensity' for 'objective probability', if one objects to the suggestion that probabilities may be non-definite. See note 3. 11 probability of Alice's truth-telling is 0.6, about 0.6, or somewhat higher than that of lying, for instance. 5. Objection and reply Libertarians might object as follows. To ascribe an objective probability to the choice before it is made is, in effect, to assimilate the choice to something like the result of a coin toss- something over which the agent has no control. But according to libertarianism, free choices are not like coin tosses, and so the argument appears to beg the question.9 There are several points to be made in response to this. First of all, nothing in the presented argument implies, or should be taken to suggest, that the agent has no control over the choice. If the choice is caused or influenced by the agent's reasons, and if agency consists, at least partly, in causation or influence by reasons, then the agent has at least some control over the choice. For instance, if Alice's reasons first raise the probability of lying to 0.7 during deliberation, and then cause her choice to lie, then Alice does exercise a kind of control in making the choice-the kind of control that consists in causation or influence by reasons. Nevertheless, Alice does not appear to choose with free will, because she seems to lack control over whether to choose one course of action rather than another. In other words, the problem and the claim implicit in the third premise (3R and 3C) is not that the agent altogether lacks control, but that the agent lacks the kind of control required for free will-the control to select which of the open alternatives to pursue (more on this in section 6). Second, the presented argument does certainly not beg the question against all libertarians. Not all libertarians reject the ascription of objective probabilities to choices before they are made. In fact, most contemporary libertarians seem to accept it (Kane 1996, van Inwagen 2000, O'Connor 2000, for instance). Third, the presented argument does not beg the question in the sense that it does not simply presuppose what libertarians deny. In particular, it does not simply ascribe objective probabilities. It gives, rather, an argument for why libertarians are committed to the ascription of objective probabilities. Now, some libertarians may go on and reject this argument as begging the question. But this move incurs a considerable cost, which the presented argument reveals. I have argued that libertarianism is committed to the ascription of objective probabilities, because any plausible account of free agency has to give an account of how the 9 This objection is due to an anonymous referee. 12 influence of reasons can reflect their normative strength, and because it seems that this requires the ascription of objective probabilities to undetermined choices and actions. Libertarians can deny this. But if they do, they owe us an alternative account of the influence of reasons on undetermined choices and action that captures the truism that this influence must come in degrees, or with varying strengths, so that their influence can reflect varying degrees in normative strength. I am not aware of any (causal or non-causal) account of reason explanation that shows how this might work, and I have argued that it is rather difficult to see how this could be shown (see section 4). To sum up, if the presented argument begs the question at all, it does so only against a minority of libertarian views, and it does not simply presuppose what they deny. It does not simply ascribe objective probabilities, but it offers an argument on the basis of general and independently plausible considerations concerning the normative strength and the influence of the agent's reasons. Moreover, it reveals the cost of denying the first premise of the chance argument (1C) for libertarians. If libertarians deny this premise, they face the burden of having to show how the influence of reasons on undetermined choices and actions can be explained without the ascription of objective probabilities and, thereby, without the assumption that an agent's reasons have the power to raise or lower the probabilities of choices and action. As far as know, no one has shown how this might work, and it is difficult to see how this could be shown. Given this, we can conclude here that the presented argument does advance the overall dialectic even if some libertarians will complain that it begs the question, because it is an argument for a premise that they reject. 6. Agent-causation to the rescue? Buchak's response to the rollback argument offers a dialectical advantage. It rejects the first premise and it thereby sidesteps the debate about the third premise (under the assumption that the second premise is uncontroversial). I have just argued, however, that libertarianism is committed to a modified (and weakened) version of the first premise that leads to the same conclusion as the rollback argument. Given this, libertarians need to engage with the third premise after all, and Buchak's dialectical advantage is lost. 13 When we turn to the third premise (3R, or the weakened 3C) we can see that the challenge is most effective against all versions of event-causal libertarianism.10 According to such views, some events are actions in virtue of their causal history: an event is an action if it is caused by the right mental states in the right way. The right way of causation is non-deviant causation. The right mental states are states that rationalize the action (such as desires, beliefs, and intentions). On this view, an agent's exercise of control consists in non-deviant causation by such reason-states. More precisely, an agent's exercise of control consists only in nondeviant causation by reason-states.11 This is why the third premise appears to be inescapable for event-causal libertarianism. If an agent's control consists only in the influence of her reason-states, and if those reasons merely bias certain choices to some degree, then it seems that the agent lacks the relevant kind of control to select one alternative rather than another. And so it seems that the choice is not made with free will (for more on this see Schlosser 2014). Buchak claimed, on the basis of her reply, that agent-causal libertarians may postulate that "agent-caused events lack objective probabilities" (2013: 25). By this she means definite probabilities, and we have seen that a lack of definite objective probabilities is irrelevant-it avoids 1R but not 1C. Does agent-causal libertarianism help to avoid the third premise? According to agent-causal views, an agent's power in the exercise of agency cannot be reduced to the influence of the agent's reason-states. Rather, the agent, construed as a persisting substance, has an irreducible agent-causal power to choose and act. Proponents of this view will stress that the objective probabilities of the relevant alternatives are conditional on antecedent mental states and events. Those antecedent states and events influence the agent's deliberations and actions. But the agent, qua substance, has the additional and unconditional power to determine (or influence) what to choose on the basis and under the 10 Event-causal libertarianism provides an account of free will in terms of an event-causal account of agency. Kane 1996 offers the most elaborate version of this view. 11 This includes the various kinds of control that an agent may exercise in mental agency (when making a decision, exercising mental effort, endorsing a desire, and so on). According to event-causal views, mental agency consists also in non-deviant causation by reason-states (desires, beliefs, and intentions). In other words, the claim that an agent's exercise of control consists only in non-deviant causation by reason-states covers even the most sophisticated event-causal accounts, such as the one proposed by Kane 1996. One may think that Kane's view raises a complication, because Kane claims that "the agent will make one set of reasons of motives prevail over the others then and there by deciding" (p. 133). But the claim that the agent can make one set of reasons prevail by deciding must either be given an event-causal analysis (in terms of non-deviant causation by desires, intentions, mental efforts, or the like), or it must be rejected as a covert appeal to an unanalyzed notion of agent-causation (given Kane's explicit commitment to an event-causal account of agency). 14 influence of those antecedent states and events. Consider again Alice, and suppose that her reasons for telling the truth strongly outweigh her reasons for lying. Her reasons, that is, raise the objective probability of her telling the truth to a much higher degree than the objective probability of her telling a lie. Given that she has an irreducible agent-causal power, she can nevertheless be said to have the power to determine (or influence) whether to tell the truth rather than a lie. In particular, if she tells the truth, it would be incorrect to say that she is fortunate or lucky. Likewise, it would be incorrect to say that she is unfortunate or unlucky if she tells a lie, despite the fact that her reasons strongly favor telling the truth. This, I think, is a credible response to the chance argument. But it comes at a high price. Agent-causal libertarianism assumes what appears to be in need of explanation. How can an agent exercise control over undetermined choices? Event-causal libertarianism proposes an explanation of the agent's control in terms of non-deviant causation by reason-states. This is an explanation of what control consist in, because we can see why non-deviant causation by reason-states is constitutive of intentional agency. Agent-causal libertarianism, in contrast, merely stipulates that an exercise of the agent-causal power is an exercise of control. This is a very substantial stipulation, because not every instance of causation is an instance of control. We can see why non-deviant causation by reason-states is an exercise of control. But there is no explanation or indication of why an instance of agent-causation is supposed to be an exercise of control-merely calling it agent-causation does not tell us why this kind of causation is a kind of control (for more on this see Schlosser 2008). In a recent discussion of the agent-causal response to the rollback argument, Shabo (2014) offers similar considerations. But he draws a stronger conclusion: "In sum, we don't transform a random outcome into an exercise of free will simply by positing a causal relationship" (170). In my view, this is an uncharitable assessment of the agent-causal position. We agree that the view cannot explain why the agent-causal relation is supposed to constitute the right kind of control (or any kind of control, for that matter). But the problem, as I see it, is not that the view fails to identify a difference between random events and agentcaused events. The problem, rather, is that it stipulates a causal power that makes this difference by definition-without, that is, explaining it. We must grant the assumption of some primitives, and we should, I submit, grant the assumption that the agent-causal power makes the right difference. And this is where we hit bedrock, as it were. All that one can do, once that is granted, is to point to the cost of introducing an agent-causal power as a primitive and to its explanatory vacuity in comparison with event-causal accounts of agency. 15 7. Conclusion Event-causal libertarianism faces the chance argument, which can be construed as a modified version of the rollback argument. It seems that agent-causal libertarianism can avoid this challenge, but only at the cost of stipulating a power that appears to be in need of explanation. One might object that this not an argument against agent-causal libertarianism, but merely a complaint. However, complaints of this sort have persuaded even most incompatibilists and libertarians that event-causal libertarianism is the only credible version of libertarianism. Given this, libertarians are caught between a rock and a hard place, and it is difficult to see how they could avoid this dilemma by embracing chance-incompatibilism.12 According to chance-incompatibilism, free choices lack definite objective probabilities. Taking this view, libertarians could avoid the first premise of the rollback argument. But we have seen that this is an empty victory. There is good and independent reason to think that libertarianism is committed to the claim that undetermined choices have some objective probability (with some degree or magnitude). And this supports the first premise of the chance argument, which has the same conclusion as the rollback argument. Does chance-incompatibilism offer any other potential benefits? As mentioned, Buchak claimed that the view opens the possibility for agent-causal libertarians to postulate that agent-caused events lack definite objective probabilities. This would, once again, allow agentcausal libertarians to avoid the first premise of the rollback argument, which would, once again, be an empty victory. As far as I can see, chance-incompatibilism does not offer any other potential advantages. To see this, consider again the role of the agent's reasons. Even if the relevant events lacked definite objective probabilities, they should still be subject to the influence of the agent's reasons (see section 4). And if the influence of the agent's reasons leaves the choice of action undetermined, as libertarianism requires, then we face again the initial question of why the agent's choice of action is not a matter of chance (probability, 12 There is another alternative. Non-causal libertarians reject both event-causal and agent-causal accounts of agency (Ginet 1990, for instance). This is very much a minority view. But it is worth noting that it does not fare any better with respect to the issues discussed here. Non-causal views do not provide an explanation of what an agent's control consist in, and they do not offer a credible way to avoid the chance argument, precisely because they do not stipulate that rational and free agents have a metaphysically irreducible power to choose what to do. Moreover, even if one denies that reasons are causes, one cannot plausibly deny that an agent's reasons should have some kind of influence on the agent's deliberations, choices, and actions. And, as I have argued, it is difficult to make sense of this without the ascription of the power to raise or lower objective probabilities (see section 4). 16 luck, fortune, or what have you). Of course, agent-causal libertarians will insist that agentcaused events are not a matter of chance because they are agent-caused. But this leads us only back to the familiar dispute concerning the stipulation of agent-causal powers-it does not identify a potential and novel advantage of chance-incompatibilism. All in all, we can conclude that chance-incompatibilism does not appear to be a promising new alternative in the free will debate, and we have seen that the debate around those issues can benefit from more attention to the role of the agent's reasons in free agency. References Buchak, L. (2013). Free acts and chance: Why the rollback argument fails. Philosophical Quarterly, 63, 20–28. Franklin, C.E. (2011). Farewell to the luck (and Mind) argument. Philosophical Studies, 156, 199–230. Ginet, C. (1990). On Action. Cambridge: Cambridge University Press. Kane, R. (1996). The Significance of Free Will. Oxford: Oxford University Press. O'Connor, T. (2000). Persons and Causes: The Metaphysics of Free Will. Oxford: Oxford University Press. Schlosser, M.E. (2008). Agent-causation and agential control. Philosophical Explorations, 11, 3–21. - (2014). The luck argument against event-causal libertarianism: It is here to stay. Philosophical Studies, 167, 375–385. Shabo, S. (2014). Assimilation and rollbacks: Two arguments against libertarianism defended. Philosophia, 42, 151–172. Van Inwagen, P. (2000). Free Will remains a mystery. Philosophical Perspectives, 14, 1–19.