Incompatibalists say that in order for us to be free, we must be able to have done otherwise than we actually did. We call this the Principle of Alternative Possibilities (PAP): an action is free if and only if the person could have acted otherwise. Because incompatiablists believe that everything is causally determined, they also believe that all of our actions lack alternative possibilities. A result of this is that incompatibalists think that we lack freedom.
Compatibalists will respond that we should interpret PAP in a hypothetical way: an action is free if and only if one would have done otherwise if one had been able to do so. Compatibalists think that the actually ability to do otherwise is not necessary for free will.
Ayer, for example, says that we should not contrast freedom with causal determinism. Rather, we should contrast it with physical force or constraint. Ayer thinks that being free is entirely compatible with the causal laws of nature. He thinks that freedom is incompatible with someone forcing you to do something or constraining your actions physically. For example, I can be free in spite of gravity but I cannot be free if someone locks me in a cage.
Ayer says there are three conditions that must be satisfied in order for an action to be the result of free will. First, if I had chosen to act differently then I should have acted otherwise. Second, the action is done without constraint or compulsion. Third, no one compelled me to do as I did. Ayer thinks that although we may live in a causally ordered world, there is still room for freedom so long as we would have done otherwise if it were possible to do so.
Chisholm objects to Ayer's view of free will. Chisholm thinks that it is not enough if a person would have done otherwise if he or she had chosen to do otherwise. Let's take the example of John Wilkes Booth's choice to shoot President Lincoln. Ayer says that this action is free if and only if Booth would have done otherwise if he had chosen to do so. Chisholm says that this is not enough. Chisholm says that the action is free if and only if Booth both (1) would have done otherwise if he had chosen to do so and (2) he could have chosen to do otherwise. Chisholm thinks that if it is not possible for Booth to have chosen to do otherwise, then his action is not free.
There are some problems with Chisholm's view. First, some think that it is silly to think that we can control what we want or what we choose to do. e.g. When I choose to run a red light, I am unable to choose to not run the red light because I can't help this overwhelming desire I have to drive fast and violate traffic laws. Second, some think that it is by the exercise of our freedom that we force ourselves into situations where we cannot act otherwise. e.g. If I am able to resist running the red light, it is only because I have trained myself and taught myself not to do so. In other words, I have created a situation for myself where I cannot choose but to obey traffic laws.
Agent causation vs. Event causation. Chisholm thinks there is another problem with determinism. He says that determinists talk only about causation where events cause other events. Chisholm thinks that there is another kind of causation: agent causation. In such cases, it is not prior events but a person who causes events to happen. Because determinism is only concerned with event causation, it does not rule out the possibility of agent causation.
Objections to Agent-Causation:
(1) Nietzsche denies that there is any such thing as agent causation. To say that an agent causes things is to say that the cause comes from nowhere, since the agent brings this new causal power into existence. Since nothing comes from nothing, this agent causation must come from something other than the agent's choice.
(2) Psychological objection. Agent causation is ultimately caused by some brain event. Hence there is no such thing as agent causation, since so-called agent causation is caused by an event in the brain. Chisholm responds: ah, but this brain event is caused by the agent! The person is still the ultimate cause of agent causation. But someone might ask further: how can both event causation and agent causation work together in a single person?
Libet's Experiments on Freedom. Libet constructed an experiment where people were told to choose to move their fingers and then also told to report when they were choosing to move their fingers. The findings showed that there was a slight delay between when a person actually began to move his or her fingers and when he or she claimed to choose to do so. In short, people were moving their fingers before they chose to do so. A simple interpretation of this experiment is to conclude that there is no such thing as free will; it is just an illusion. However, someone might note that there will be a gap of time between when someone makes a choice and when someone is able to report on that choice being made. Either way, there is nothing in Libet's work that indicates that our actions tomorrow do not depend on the choices we make today.
Harry Frankfurt comes in with further refinement of a compatiablist position. First, he distinguishes between first-order desires and volitions and second-order desires and volitions. First order desires are just desires to do something, such as my desire to drink peppermint tea. A second-order desire is a desire to have a desire, such as a desire to have the desire to drink coffee instead of tea. A first-order volition, or will, is just a successful first-order desire. For example, if my first-order desire to drink tea is successful and I do drink tea, then this is a first-order volition. A second-order volition is a successful second-order desire. For example, if my desire to desire coffee rather than tea is successful and I therefore drink coffee instead of tea, this is a second-order volition.
Frankfurt thinks that people who lack second-order desires and second-order volitions are wanton. A wanton does not care about his or her will but only follows his or her desires as they arise. Animals, for example, are wantons. Frankfurt thinks that what separates us from animals is our ability to reflect on and think about our desires.
Frankfurt thinks that a person is free if he or she is able to want what he or she wants to want. In other words, a person is free if he or she is able to have the will that he or she wants to have. A wanton drug addict, for example, who only has first-order desires and volitions is not free according to Frankfurt. Likewise, an unwilling addict who may have second-order desires not to do drugs but is unsuccessful in realizing these desires is also not free. Similarly, even the willing addict is not free because although the willing addict has second-order volitions, this is not because of a choice the willing addict has made. The desire a drug addict has to desire drugs will be realized whether or not there actually is a desire to desire drugs. Hence no drug addicts are free.
Strengths of Frankfurt's View: (1) It explains why we are better than animals, (2) It explains the will in terms of desire, which is simple to understand and (3) It explains why we want freedom of will (because we want to satisfy desires).
Regress Objection to Frankfurt's View: (1) If the goal is to have second-order desires and volitions, why not third-order or fourth-order, too? We can go on and on and have more reflective desires. This is the problem of infinite regress. Frankfurt responds: But there are desires that we identify with, we see ourselves as being made up of the second-order desires. Also, perhaps the second-order desires are determined, or caused by external events. On objection to Frankfurt here is that if our second-order desires are determined, then we lose free will.
Moral Responsibility vs. Free Will. Frankfurt says that the addict may not be free, but he is morally responsible. Frankfurt gives two conditions for moral responsibility: (1) a person must be able to predict the consequences of his or her action and (2) a person must have been able to have done otherwise. Freedom requires that we can control our second-order desires and volitions whereas moral responsibility merely corresponds, or goes along with, our second-order desires and responsibilities. Frankfurt thus reformulates the PAP: A person is not moral responsible if he or she acted only because he or she was unable to act otherwise.