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Suppose Mother Teresa discovers a hand-grenade in an orphanage in Calcutta. As you might expect, she picks up the handgrenade in order to dispose of it safely. But now an utterly uncaused event occurs: to her horror, her hand suddenly pulls out the pin and throws the grenade into the heart of the orphanage. The grenade explodes, resulting in mayhem and destruction. When I say ‘uncaused’, I really mean that there is no cause, none whatsoever. As I am imagining the example, the action of pulling the pin and throwing the grenade was not caused by any decision on Mother Teresa’s part; nor did it have an external physical cause. No dormant dark side of Mother Teresa’s personality has Wnally come to light. She has no nervous tic. Her hand simply Xew up from absolutely no cause whatsoever. This clearly is not a free action. We could not blame Mother Teresa;
she is the victim of a cruel accident.
Free Will and Determinism 119 The alarming thing for libertarians is that Mother Teresa seems unfree precisely because her action was uncaused. Freedom now appears to require causation. This obviously threatens the fundamental libertarian claim that the key to the problem of freedom is indeterminism of human action. Libertarians must somehow distinguish between free undetermined action and randomness.
Some libertarians address this problem by postulating a special kind of causation that only humans wield, called agent causation. Ordinary mechanistic causation, the kind studied in physics and the other hard sciences, obeys laws. Mechanistic causes are repeatable and predictable: if you repeat the same cause again and again, the very same eVect is guaranteed to occur each time.
Agent causation, on the other hand, does not obey laws. There is no saying which way a free human being will exercise her agent causation. The very same person in exactly similar circumstances might agent-cause diVerent things. According to the theory of agent causation, you act freely when (i) your action is not caused in the ordinary, mechanistic way, but (ii) your action is caused by you—by agent causation. If you freely decide to eat Wheaties one morning rather than your usual helping of Apple Jacks, it would have been impossible to predict beforehand which cereal you would choose. Nevertheless, your choice was not a random occurrence, for you yourself caused it. You caused it by agent causation.
It is unclear whether agent causation really solves the problem of randomness. Consider what an agent-causation theorist would say about your freely making a diYcult decision. There are two important factors in decision-making: what you desire, and what you believe is the best means to achieve that desire. If you are undecided whether to vote Democratic or Republican, for instance, this is because some of your beliefs and desires favor a Democratic vote, and others favor a Republican vote. Suppose that, in the end, the set favoring a Democratic vote wins out.
Free Will and Determinism A libertarian would say that mechanistic causes that occurred in the past did not determine this outcome. It was you yourself, via agent causation, that selected the Democratic vote. Your selection was subject to no laws; it was unpredictable. This activity of agent causation was not caused by your beliefs and desires. But now—and here is the problem—since the selection was not causally based in your beliefs and desires, it seems entirely detached from you. The selection did not emerge from what you know about the candidates and what sort of leader you want for your country. Your vote didn’t arise from who you are. It just appeared in the world, as if by magic. Given this, it would be odd to praise or blame you for it. And this suggests that it was unfree.
Whether or not libertarianism relies on agent causation, its most worrisome feature is its clash with science. First, libertarians must reject the possibility of an all-encompassing psychology. Human behavior would be governed by the laws of such a science, and libertarians deny that human behavior is controlled by any laws. But the clash does not end there. Libertarians must also reject the possibility of an all-encompassing physics.
The realms of psychology and physics cannot be neatly separated, for human bodies are physical objects, made up of subatomic particles. An all-encompassing physics could predict the future motions of all particles—even those in human bodies— based on the earlier states of particles. Since libertarians say that human behavior cannot be scientiWcally predicted, they must deny the possibility of such a physics. According to libertarians, if physicists turned their measuring instruments on the subatomic particles composing a free person, formerly observed patterns would break down.
This attitude toward science seems rash. Here in the twentyWrst century, we have the beneWt of hindsight on various disagreements between science, on the one hand, and religion and philosophy, on the other. Remember the Catholic Church’s Free Will and Determinism 121 decision to censor Copernicus and Galileo for saying that the Earth moves around the Sun. No one wants to repeat that mistake. And remember the dramatic successes of science, both theoretical and technological. Of course, science is not infallible. But a philosopher had better have very good reasons to declare that an existing science is just plain wrong, or that a certain kind of scientiWc progress will never happen. One’s philosophy should avoid colliding with or limiting science.
Our choices look grim. On the one hand, there is the dismal philosophy of hard determinism, which robs life of all that is distinctly human and worthwhile. On the other hand, there is the radically anti-scientiWc philosophy of libertarianism— which, given the problem of randomness, may not even succeed in salvaging free will.
Interlude: Quantum Mechanics
Before moving on, we should investigate a side issue—whether quantum mechanics bears on the problem of freedom. Quantum mechanics is a theory about the behavior of tiny particles.
This theory was developed in the early part of the twentieth century and continues to be accepted by physicists today. Quantum mechanics (or at least, a certain version of it) is a radically indeterministic theory. It does not predict with certainty what will occur; it only gives probabilities of outcomes. No matter how much information you have about a particle, you cannot predict with certainty where it will be later. All you can say is how likely it is that the particle will be found in various locations. And this is not a mere limitation on human knowledge. The particle’s future position is simply not determined by the past, regardless of how much we know about it. Only the probabilities are determined.
In the previous sections I was ignoring quantum mechanics.
For instance, I assumed that if a cause occurs, its eVect must Free Will and Determinism occur, even though quantum mechanics says that causes merely make their eVects probable. Why did I ignore quantum mechanics? Because randomness is not freedom. Let us try a little thought experiment. First pretend that quantum mechanics is incorrect and physics is truly deterministic. The threat to human freedom that this presents is what we have been talking about so far in this chapter. Next, in each person’s brain, add a little lottery, which every so often randomly causes the person to swerve one way rather than another. This is like what quantum mechanics says really happens: there is an element of randomness to what events occur. Does the threat to freedom go away? Clearly not. If the original, wholly determined person had no free will, then the new, randomized person has no free will either; the lottery injects only randomness, not freedom or responsibility. And as we learned from the case of Mother Teresa, randomness does not mean freedom. If anything, randomness undermines freedom.
A libertarian might concede that quantum randomness is not suYcient for freedom, but nevertheless claim that quantum randomness makes room for freedom, because it makes room for agent causation. Imagine that it is 1939, and Hitler has not yet decided to invade Poland. He is trying to decide what to do
among the following three options:
Invade Poland Invade France Stop being such an evil guy and become a ballet dancer Quantum mechanics assigns probabilities to each of these possible decisions; it does not say which one Hitler will choose.
Suppose, for the sake of argument, that the probabilities are as
95.0% Invade Poland 4.9% Invade France 0.1% Become a ballet dancer Free Will and Determinism 123 After assigning these probabilities, the work of quantum mechanics is complete. According to some libertarians, agent causation now steps in. After quantum mechanics sets the probabilities, Hitler himself chooses, by agent causation, which decision he will in fact make. Physics sets probabilities, but people, by agent causation, ultimately decide what occurs.
If this picture were correct, then my criticism of libertarianism as being anti-scientiWc would be rebutted: agent causation could peacefully coexist with quantum mechanics. In fact, though, the coexistence picture makes agent causation a slave to quantummechanical probabilities.
Imagine running the following interesting (if wildly unethical) experiment. First produce one million exact clones of Hitler as he was in 1939. Then, in one million separate laboratories, reproduce the exact conditions that Hitler faced before he decided to invade Poland. Put each clone in his own laboratory and deceive him into thinking that it is really 1939 and that he is in charge of Germany. Then sit back and watch. Record how many clones attempt to invade Poland, how many attempt to invade France, and how many attempt to become ballet dancers. The coexistence picture says that you will observe a distribution of behaviors that roughly matches the probabilities listed above, for the coexistence picture says that quantum mechanics correctly gives the probabilities of outcomes. Thus, you will observe around 950,000 clones trying to invade Poland, around 49,000 trying to invade France, and around 1,000 practicing ballet. If you repeat the procedure again and again, you will continue to observe outcomes in approximately the same ratios. (The more times you repeat the experiment, the closer the total ratios will match the probabilities, just as the more times one Xips a coin, the closer the ratio of heads to Xips approaches one-half.) If you change the laboratory conditions faced by the clones, so that quantum mechanics predicts diVerent probabilities, you will observe a new distribution of behaviors that Wts the new Free Will and Determinism probabilities. The distribution keeps following what quantum mechanics says.
What good then is agent causation? It seems to mindlessly follow the probabilities, having no eVect of its own on the distribution of outcomes. This sort of agent causation is empty;
it adds nothing to freedom or responsibility. Agent causation, if it is to be worth anything, must be capable of disrupting the probabilities given by quantum mechanics. There can be no peaceful coexistence: agent causation theorists must clash with science. Quantum mechanics does not help the agent-causation theorist. So I will go back to ignoring quantum mechanics.
We are back to the grim dilemma. Apparently, we must reject science or reject freedom. Yet neither option seems at all appealing.
Many philosophers believe that there is a way out of this dilemma. Others think that this way out is a big mistake. You must decide for yourself.
The way out is called soft determinism. According to soft determinists, our discussion took a wrong turn all the way back when we said that the available options were rejecting freedom or rejecting determinism. Soft determinists say that this overlooks a third option. We can have our cake and eat it too: we can retain both freedom and determinism. That way we can preserve both our science and our humanity. The argument in the Wrst section, which concluded that freedom and determinism are opposed to each other, was a mistake. The alleged conXict is an illusion, based on a misunderstanding of the concept of free will. Our actions (or at least their probabilities) are indeed caused by events before our births. But they are often free despite this.
Free Will and Determinism 125 To explain what soft determinists are up to, let’s Wrst consider some examples. Imagine a very young boy with a serious misunderstanding of the concept of a man. This boy thinks it is part of the deWnition of the word ‘man’ that men never cry. As far as he knows, the men in his family never cry, the men on television never cry, and so on. He believes that his father is a man, of course, but one day he sees his father crying. The boy becomes very confused. Two of his beliefs now conXict: his belief that his father is a man and his belief that his father is crying. Which should he give up? Should he decide that his father is not a man after all? Or should he decide that his father was not really crying—that he was only cutting up onions, say? Obviously, he should do neither. Instead, he should clear up his conceptual confusion about the nature of manhood. Then he will see that his beliefs about his father’s manhood and about his father’s crying are compatible after all.
Here is a second example. How would you deWne the word ‘contact’, as in ‘Barry Bonds’s bat made contact with the baseball’? If you are like most people, your Wrst answer is probably something like this: things are in ‘contact’ when there is no empty space between them. But now remember your high-school science.