A Cumulative Case for Libertarian Freedom
What follows is an argument for libertarian freedom. To start, I’ll address some key terms.
What is libertarianism? As I am using this term, it does not refer to the political theory or to any corresponding political party. Rather, libertarianism is a position in metaphysics about the nature of free will. More precisely, libertarianism is the conjunction of two propositions: (a) incompatibilism is true and (b) human beings have free will, at least sometimes.[1]
Incompatibilism is the view that causal determinism (CD) and human free will are not compatible, i.e., that both cannot be the case. CD is the position that for any event e, the conjunction of the laws of nature (L) and the complete set of events during the history of the universe prior to e (H) is jointly sufficient for e. In other words, at any moment, only one future is possible, given L and H. The future is not open to us. If L or H or both had been different, which is logically possible, then some other future would unfold; nevertheless, given the contingent facts of L and H, there is only one future path available — which means that for any choice one takes oneself to be making, L and H are sufficient to cause that choice such that no other option is possible given L and H.[2] Hence, on incompatibilism, if determinism is true, then human beings lack free will. Incompatibilists who hold that determinism is true are called hard determinists; they deny human free will and moral responsibility. Incompatibilists who hold that determinism is false and who affirm free will/moral responsibility are libertarians.
What is free will? Roughly, it is the mental ability to choose such that one has the kind of control over one’s choice that is necessary for moral responsibility regarding that decision. As noted, libertarians hold that this ability is inconsistent with CD. On the other hand, compatibilists hold that this ability is consistent with CD; i.e., it is at least possible that CD is true and that we have free will. (Soft determinists hold that free will and determinism are in fact both the case. Sometimes, ‘compatibilism’ and ‘soft determinism’ are used interchangeably, but there is this subtle distinction to keep in mind.)
Now that these key terms are covered, consider some reasons for accepting that human beings have libertarian free will (LFW). The first two reasons support incompatibilism; the remaining considerations support the claim that we have free will. Together, they form a cumulative case for libertarianism.
1. The Consequence Argument (CA)
This argument has been developed and advocated by Peter van Inwagen, among others, though its main idea is present with the ancient Greeks. CA can be articulated in different ways; van Inwagen has expressed it as follows: “If determinism is true, then our acts are the consequences of the laws of nature and events in the remote past. But it is not up to us what went on before we were born, and neither is it up to us what the laws of nature are. Therefore, the consequences of these things (including our present acts) are not up to us.”[3]
Here is another way to state the argument. Recall the working definition of CD above. Arguably, if the conjunction of L and H are sufficient to bring about e, then we humans have no control over e, since we have no control over L, H, their conjunction, or their causation of e. If this is the case, then we are wholly passive concerning e. (One might use “impotent” rather than “passive,” as Peter Unger does in Impotence and Causal Determinism.) We are passive instruments moved by nature and the events of the past, and thus our actions are not up to us.
To elaborate, note that no human being is free to change the existence or the causal efficacy of L. And no human being can control H. Moreover, no human being can do anything to prevent the conjunction of L and H. Furthermore, if CD is the case, the fact that this conjunction is sufficient to bring about e is not up to us. These points are untouchable for human beings; we cannot do anything to change them. Given these assumptions, no human being is free to control the occurrence or the non-occurrence of any event whatsoever, including those occurrences which are his own actions. We are wholly passive; we do only what we are causally determined to do; our doings are not up to us.
Now assume arguendo that CD is the case. As such, L and H are sufficient to bring about e. Thus, we are passive and not free with respect to the occurrence of any event, including our own choices and behaviors. There seems to be no room whatsoever for us to exert any freedom or influence at all, since we have no control over our actions, no control over the factors that cause them, and no ability to act as the source of our own action. Notice that the assumption of CD entails that we are not free. Hence, CD is incompatible with human freedom. Moreover, if CD is incompatible with human freedom and we are nevertheless free, then we have LFW and CD is false.
2. The Manipulation Argument (MA).
Philosophers such as Derk Pereboom and Alfred Mele have addressed this argument in detail. According to the MA, briefly, for cases in which one person forces another person to act, the sort of coercion involved is sufficient to prevent that act from being done freely. But there is no morally relevant difference between such cases and the causal influence involved in CD. On CD, one’s actions are causally determined by factors other than oneself in a way that is relevantly similar to the way in which a person’s coerced act is caused by someone else. Now, like cases should be treated alike. Thus, on this argument, since no person’s action that is coerced by another is a free action, no person’s action that is causally determined in a deterministic universe is a free action.
For example, suppose that Neuroscientist Ned knows enough about Smith’s brain to exert complete control over it via commands Ned types into his laptop computer. Ned types the command that forces Smith to kill Jones. As a result of this command, Smith kills Jones, which is something he would not have done had Ned not typed the command.
It is clear that Smith is not morally responsible for killing Jones, since he did not do it freely. He had no control over his action, which was caused by Ned. Ned acted through the passive instrumentality of Smith’s body. Ned is responsible for killing Jones, and if it is a wrongful killing which Ned performed deliberately, then Ned is guilty of murder. Smith is not guilty of murder. Actus non facit reum nisi mens sit rea. (An act does not make one guilty unless the mind is guilty; a person is guilty only if the act is done knowingly and willfully.)
Similarly, if ours is a causally determined universe, then our actions are ultimately caused by factors external to us over which we have no control. Thus, our actions are not free and we are not morally responsible for them if CD is true. Hence, incompatibilism is true.
3. Human Experience
There is a common presupposition in human experience and ordinary activity that we are free to choose, at least sometimes. Moreover, we often assume freedom as a critical aspect of understanding ourselves, the human experience, and our moral lives. Hence, the burden of proof is on the denier of free will. We are justified in believing that we are free unless and until there is a sufficient argument to the contrary. But there is no sufficient argument to the contrary. Hence, we are justified in believing that we have free will.
4. Intuition
One might claim to have a strong intuition that one is free. Upon introspection, one might claim to have the clear experience of being free when choosing, say, to go out and exercise rather than stay home and watch television. This intuition alone is insufficient to prove conclusively that we are free, but the intuition might be strong enough to warrant belief in free will, and furthermore, strong enough to block plausible but inconclusive arguments against free will.
5. Proper Basicality
This reason is similar to (4). Here, one might claim that belief in free will is epistemically properly basic, i.e., that it is a matter of direct experience that we are free and therefore one needs no independent evidence to justify the belief that one is free. This direct experience is sufficient for something like knowledge by acquaintance of one’s freedom, and such knowledge does not require an independent supporting argument.
6. We Live As If Free
We live as though we are free. Even those who deny free will and moral responsibility act as if they and others are free and responsible, holding people morally accountable and taking them to be proper recipients of praise, blame, reward, and punishment.
7. Moral Responsibility Entails Freedom
We are morally responsible, and virtually everyone assumes so. Since moral responsibility entails freedom, we are justified in believing that we are free.
8. Reason Indicates Freedom
We can reason. We can rationally accept conclusions on the basis of evidence. This suggests that we are free. (This sort of argument goes back at least to Kant.)
9. Practical Presupposition
Even if in fact we are not free, we do not know that we are not free. But practically speaking, so much of human life hangs on our being free such that in the absence of compelling proof that we are not free, one is justified in presupposing that one is free. Of course, this does not prove that we are free, but it does seem to justify the assumption that we are free.
10. Categorical Morality
If one categorically ought to do x, then one should do x regardless of any desire, preference, emotional pull, or any other sort of inclination not to do x. Arguably, we have categorical oughts. Thus, we should do what we categorically ought regardless of any inclination otherwise. But this means that we can do what we categorically ought, despite the pull of desire which might incline us against our moral duty. (Ought implies can.) And this means that we are free to do what we ought. The will is free and autonomous, in Kant’s sense.
Together, these ten reasons constitute a cumulative case argument for (a) and (b), and thus a substantive defense of libertarianism. It is nevertheless important to note that there are objections to libertarianism. I will try to address those in a separate post.
[1] The sort of free will here is a matter of disagreement between libertarians; for example, some might say that the control condition, the ability to do otherwise, the rationality condition, and/or the sourcehood condition are necessary for free will. To simplify matters, I’ll say here that libertarianism requires (a) and (b).
[2] It is important to distinguish CD from fatalism. Fatalism is the claim that whatever happens is a matter of metaphysical necessity. I.e., for any event e that has occurred, is occurring, or will occur, if e occurs, then it is not broadly logically possible that e does not occur; there is no possible world in which e does not occur.
[3] The Consequence Argument. (In Metaphysics: the big questions, Second Edition, eds. Peter van Inwagen and Dean W. Zimmerman. Oxford: Blackwell Publishing, 2008), p. 450.