Peter van Inwagen defines free will as an ability to make decisions between two options when at least sometimes I could possibly choose the other option. In other words, to have free will requires that I can actively choose a number of different actions. van Inwagen thinks that someone lacks free will if he or she never has the ability to choose alternative actions. Sam is free to perform an action if and only if Sam could have done something else other than this action. For example, I am free to take notes in lecture if and only if I could have done something else other than take notes in lecture. Because I could have stayed home in bed, I did freely choose to come to lecture and take notes. van Inwagen is what we call an incompatibalist, which means that he thinks that determinism is true and that the truth of determinism entails the impossibility of free will.
Causal determinism is the view that a state of affairs in the world determines, or directly causes, the following state of affairs. In other words, what happens in the world is a direct result of what has happened previously. Laws about the physical world such as the laws of physics and chemistry control what happens in the world. The idea is that if we were able to perfectly understand the physical state of the world and we applied physical laws to the current state then we would be able to perfectly predict what the future will be like.
The Determinist Argument against Free Will:
1. If your action is determined by prior causes, then you couldn't have done otherwise (the act is not free).
2. If your action is not determined by prior causes, then it is a chance event (the act is not free).
3. Either your action is determined by prior causes or not.
4. Therefore, you don't act freely.
A.J Ayer on Premise 2: Either my actions are accidents or not. It is either a matter of chance or not how I act. If my action is only done by chance, then clearly I cannot be held responsible for my action. But if my action is not by chance but because I chose to do so, then there seems to be a causal explanation for my choice, in which case we also end up with an action that is the result of a deterministic world.
There are four basic positions in the free will debate.
Compatibalism is the view that determinism is compatible with free will.
Incompatibalism is the view that determinism is incompatible with free will. If determinism is true, then we cannot be held responsible for our actions.
Hard Determinism is the view that free will is incompatible with free will and that determinism is true, so we lack free will and we lack responsibility.
Libertarianism is the view that determinism is incompatible with free will and that we have free will, so determinism is false.
Causal Determinism vs. Fatalism. Fatalism is the view that whatever happens happens because it has to. Whatever will be has to be. Fatalism results in the necessary view that free will is impossible since every action is done because it is necessary (not because it is chosen). In other words, fatalists think that human action has no influence on events in the world and that freedom is merely an illusion. Determinism is not necessarily committed to the view that free will is impossible. Some determinists think that free will is possible but no fatalists think that free will is possible.
Aristotle's Sea Battle Argument for Fatalism. Aristotle makes use of the law of the excluded middle (LEM), which states that for any statement, it must either be true or false (it cannot be both true and false).
1. It is necessary that it is either true or false that the sea battle will happen tomorrow.
2. If it is true that the battle will happen tomorrow, then it is necessarily true that there will be a sea battle tomorrow.
3. If it is false that the battle will happen tomorrow, then it is necessarily false that there will be a sea battle tomorrow.
4. If is now either necessary that the battle will happen or it is necessary that the battle will not happen.
Aristotle wants to reject fatalism, so he denies the first premise. In short, he denies that LEM applies to statements about what may or may not happen in the future.
Another Argument for Fatalism:
1. Either you will be killed by a bomb or you will not be killed by a bomb.
2. If you are going to be killed by a bomb, then any precautions you take are useless.
3. If you are not going to be killed by a bomb, then any precautions are useless.
4. It is pointless to take precautions.
Premise 3 is unrealistic. It seems that someone might avoid being killed by a bomb exactly because he or she took precautions! For premise 3 to be true, the following must be true: "If you had not taken precautions then you would still not have been killed". But this does not follow from the truth of "you are not going to be killed". Just because someone is not killed does not mean that he or she would not have been killed even if he or she had taken no precautions.
Ayer thinks that he has a thought experiment that makes the view of fatalism appealing. Imagine you found a book that perfectly describes every detail about your life. In fact, it describes not only your past life but also your future life. Ayer wonders if such an occasion would be a good reason to accept fatalism. Sven thinks that this is a bad argument for fatalism. Just because someone knows what you will do does not entail that you lack control over what you will do.
Peter van Inwagen is a perfect example of an incompatibalist. He thinks that we cannot control the laws of nature or past events. Because of this, the consequences of past events and the laws of nature are not in our control.
van Inwagen's Argument for Incompatibalism:
1. If determinism is true, then past events make my current action of raising my hand necessary.
2. If I could have avoided raising my hand now then it would not be true that I now raise my hand.
3. If I could make it false that I raise my hand now, then because past events entail me presently raising my hand, then I also make all past events false.
4. There is no way to make all past events false.
5. If I could make all past events false, then I could make all laws of nature false.
6. There is no way to make all laws of nature false.
7. Therefore, if determinism is true, then there was no choice but to raise your hand in the present.