Free Will and Determinism

Free Will and Determinism


This is a quick look at issues concerning the nature of free agency. There are three important questions about free will and determinism, but only one of them is really a philosophical question. Ayer mentions all three questions in his opening paragraph (Bailey, p. 558): "It is commonly assumed that men are capable of acting freely, in the sense that is required to make them morally responsible, and that human behavior is entirely governed by causal laws: and it is the apparent conflict between these two assumptions that gives rise to the problem of the freedom of the will." Ayer is pointing out that the following three assumptions are jointly incompatible:

1. people are capable of acting freely
2. determinism is true ("human behavior is entirely governed by causal laws")
3. acting freely and being causally determined are incompatible

1. Is Determinism True or False?

Here are three more or less equivalent ways of defining determinism:

1. Everything has a sufficient cause.  (A "sufficient cause" is a cause which suffices to insure that the event in question will take place.)

2. The facts about the state of the universe at a given time, together with the laws of nature, imply the state of the universe at any later time.

3. If one knew enough about the state of the universe at a given time, and the laws of nature, and had sufficient computational power, one could predict the state of the universe at any later time.

It should be noted that quantum physics is generally believed to show that determinism is false. Nevertheless, it remains an interesting issue whether freedom is compatible with determinism, because (1) it is not clear that quantum indeterminacies have an effect on human action, and (2) if they do, it is hard to see how this could be the sort of effect which helps make it intelligible how we could be free.

It was once thought that whether determinism is true or false was a philosophical issue that could be settled a priori. However, it seems better to regard it as an empirical issue which will be settled by physics, not philosophy.

2. Do we have free will?

This also is a question we can't answer a priori; it requires evidence. (It seems to be more a question for psychology than for philosophy.)

You might think it could be answered simply by examining our own choices. I am conscious of making decisions; I then perform the corresponding actions. Doesn't that prove that I have free will?

Answer: no, it doesn't. It is entirely possible that I could have the experience of choosing freely even though in fact I never do.

To illustrate this point, consider the following examples from Daniel Wegner, The Illusion of Conscious Will (MIT Press, 2002).

First, a quotation from an article by Jose Delgado: "In one of our patients, electrical stimulation of the rostral part of the internal capsule produced head turning and slow displacement of the body to either side with a well-oriented and apparently normal sequence, as if the patient were looking for something. This stimulation was repeated six times on two different days with comparable results. The interesting fact was that the patient considered the evoked activity spontaneous and always offered a reasonable explanation for it. When asked, 'what are you doing?' the answers were, 'I am looking for my slippers', 'I heard a noise', 'I am restless', and 'I was looking under the bed'." (Wegner, p. 46.)

Second, an experiment with magnets which influence brain function. "In this experiment, a stimulation magnet was poised above the participant's head and aimed in random alternation at the motor area on either side of the brain. Then the participant was asked to move a finger whenever a click was heard (the click of the electrical switch setting off the magnet). Participants were asked to choose freely whether to move their right or left index finger on each trial. Then the magnet was moved around while they responded. Although the stimulation led the participants to have a marked preference to move the finger contralateral to the site stimulated, particularly at short response times, they continued to perceive that they were voluntarily choosing which finger to move." (Wegner, pp. 47-48.)

The point I want to make with these examples is not that we don't have free will. Rather, the point is that we can't prove that we have free will by pointing out that it seems as though we do. The examples show that it is quite possible to have the experience of free will even when we don't actually have free will itself.

3. Is free will compatible with determinism?

This is the key philosophical question. Does determinism rule out the possibility of free will, or could we be genuinely free even if the universe is a deterministic place?

It seems that the best way to answer this question is in two stages. First, we need a plausible analysis of what it means to act freely (or choose freely). Second, we need to see whether this definition is compatible with the truth of determinism.

Classification of Views about Free Will

  determinism is true determinism is false
free will is compatible with determinism (i.e. compatibilism is true) soft determinism [no name]
free will is not compatible with determinism (i.e. incompatibilism is true) hard determinism libertarianism

Note:  the view that there are causal constraints on action, but that our actions are not entirely determined by these constraints, is not soft determinism. Rather, it is a version of libertarianism. Determinism is the view that every event is completely determined by prior causal factors, so any view that denies this cannot be a version of determinism.

Attempts to Define Freedom

It is interesting to attempt to specify necessary and sufficient conditions for an action to be free.  Incompatibilists (hard determinists and libertarians) hold that one necessary condition of an action's being free is that it is not (completely) caused. This clearly does not provide a sufficient condition, since various subatomic events (e.g. the decay of a radioactive atom on a particular date) are not completely caused, but are also not therefore free.

Compatibilists think that in fact not being caused is not only not a sufficient condition for freedom, but not even a necessary condition.  The basic trouble with the idea that free actions must be uncaused, in their view, is that, to the extent that an action is uncaused, it seems to be random:  we happen to perform one action, but there is no explanation of why we performed this action instead of some other.   This seems to reduce the realm of free action to utterly trivial decisions:   if I am completely indifferent as between chocolate and strawberry, then my decision between the two flavors might be random or arbitrary in the relevant sense.   But the cases in which we are most interested in freedom of action are cases in which we do have reasons that favor one action over another. It seems that in such cases there is an explanation of why we perform the action in question instead of some other action, and the fact that there is an explanation of the action seems to imply that it is caused.  The view of compatibilists, then, is that free actions are not uncaused actions, but rather actions that are caused in a particular way.

A first attempt at a compatibilist definition might be this:

1. An action is free if and only if its cause is internal to the agent rather than external to the agent.

However, this clearly is not a successful definition, since an action can have internal causes and yet not be free (for example, sneezing has internal causes but is not a free action).  A second attempt might be:

2. An action is free if and only if it is caused by the agent's beliefs and desires.

This seems much more plausible.  However, there still appear to be counterexamples -- that is, cases in which an action is caused by an agent's beliefs and desires and yet is not a free action.  Apparent counterexamples include:

A compatibilist might argue that the first two counterexamples rest on mistakes about brainwashing and addiction, and that in the second two cases we actually are free in the relevant sense.  Or the compatibilist might agree that these are counterexamples to the proposed definition, and try to construct a more sophisticated definition. Ayer's suggestion is that an action is free if it is unconstrained; he elaborates this into a definition as follows (Bailey, p. 562):

3. An action is free iff:
        (1) I would have acted differently if I had so chosen;
        (2) My action was voluntary (rules out inner constraint, as in kleptomania);
        (3) No one compelled me (rules out outer constraint)

Last update: April 16, 2012.
Curtis Brown | Introduction to Philosophy | Philosophy Department | Trinity University