PHIL 80: MIND, MATTER AND MEANING Paper 1 – Final Version Prompt 2:

A crucial thought behind Van Inwagen’s Consequence Argument is that we lack the ability either to change the past or change the laws.

If determinism is true, he argues, our present actions are a direct combination of the past and the laws. And on that basis, he concludes that if determinism is true then what we in fact do is all that we can do. David Lewis rejects this reasoning. He claims that while there is sense in which we cannot break the laws of nature, there is also a sense in which we can break the laws of nature. Moreover, he claims that once we appreciate this distinction, Van Inwagen’s argument for the incompatibility of freedom and determinism collapses. Who has the better of this dispute? Write a paper which answers that question.

There are many possible strategies you might adopt. For example, you could defend Van Inwagen against the claim that his argument cannot go through if one consistently adopts either the strong or the weak reading of “could have broken a law.”

Alternatively, you could argue on behalf of Lewis by trying to anticipate Van Inwagen’s best possible response to his argument and then showing that that best possible response still fails to salvage the consequence argument.

It is important that if you choose to write such a paper, you should not simply do a “Lewis says, Van

Inwagen says” summary. You should add some critical insight of your own to the conversation.

Response: Word Count: 1212 In the article “An Argument for Incompatibilism”, Van Inwagen employs six premises to prove that humans’ free will could not co-­‐exist with determinism. If determinism applies, all events, including the agents’ actions, are predetermined outcome of past events; the agent thus has no power to choose his actions. David Lewis disagrees with this. In the article “Are we free to break the laws?”, he introduces the distinction between breaking the laws in the weak sense, and in the strong sense. Lewis shows that no matter whether we adopt the weak or strong definition, one premise out of six premises in Inwagen’s argument must be wrong. Hence, Inwagen’s argument lacks validity and is incorrect. This paper aims to prove that Lewis’ distinction is not meaningful because weak and strong definitions are the same. Furthermore, inaccurate definitions render Lewis’ conclusion against Inwagen’s arguments invalid. Consequentially, this paper defends Inwagen’s thesis that free will is incompatible with determinism. Inwagen proposes six premises to prove that free will is not compatible with determinism. First, he lets T be the time when agent J conducts action A, and lets P be the state description at time T. Inwagen argues that if determinism is true, P must

be the consequence of H, the world’s history up to time T, and the laws of physics L. Second, because P encompasses everything in the world at time T, it is not possible for agent J to not conduct act A at time T when P is true. Third, hence, if agent J diverges from act A at time T, he must render P false. Fourth, because P is the conjunction of H and L, as agent J renders P false, he also renders the conjunction of H and L false. Fifth, because it is impossible to render the history false, agent J’s ability to render the conjunction of H and L false implies his ability to render L false. Sixth, agent J could not render the laws of physics L false in a deterministic world. Assuming determinism is true, all six premises above are true. If all six premises above are true, agent J is unable to act differently from what he is predetermined to do and, consequentially, does not have free will. In conclusion, free will could not co-­‐ exist with determinism. Lewis distinguishes between breaking the laws in the weak sense, and in the strong sense, and argues that if we consistently choose either definition, one of Inwagen’s six premises must be wrong. According to Lewis, an agent can break the laws in the weak sense when he “can do something such as, when [he] do it, a law would be broken”1; an agent can break the laws in the strong sense when he can conduct an act that is itself “a law-­‐breaking event”, or an act that “would cause a law-­‐breaking event”2. While the ability to break the laws in the strong sense implies the ability to break the laws in the weak sense, the reverse is not true. Moreover, if we consistently adopt only the weak definition, Inwagen’s sixth premise is false. The

1 Lewis, D. “Are we free to break the laws?”. Watson, G. Oxford Readings in Philosophy, 2003.“Free Will”. P.124 2

Ibid.

sixth premise says that agent J cannot break the laws. However, agent J can still break the laws in the weak sense. For example, he can change his act at time T such that if he did, there would have been a law-­‐breaking event prior to time T. In contrast, if we consistently adopt the strong definition, the fifth premise is false. According to the fifth premise, if an agent can render the conjunction of history H and laws L false, he can also render L false. However, agent J can, in the strong sense, render the conjunction of H and L false by changing his act such that there must have been a law-­‐breaking event in the past. In this case, he renders L false in the weak sense, but does not render L false in the strong sense. Overall, Lewis points out a validity problem in Inwagen’s consequence arguments: no precise definition of “ability to break the law” allows all Inwagen’s premises to be true. This paper argues that not only breaking the laws in the strong sense implies breaking the laws in the weak sense, as Lewis has pointed out, but breaking the laws in the weak sense also implies breaking the laws in the strong sense. Thus, weak and strong senses are the same; the distinction is meaningless. Specifically, this paper explores cases where agent J breaks the laws in the weak sense, and proves that he must also break the laws in the strong sense. Assume that agent J breaks the laws in the weak sense at time T. There are three possible implications: he must conduct an act that is a law-­‐breaking event, or an act that leads to a law-­‐breaking event, or an act that leads to a “divergence miracle” – a change in the course of history prior to time T that includes a law-­‐breaking event. For the first two scenarios, it is clear that agent J breaks the laws in the strong sense. For the last scenario, in order for the

“divergence miracle” to take place, agent J must change the course history prior to T. The law of physics states that the past is fixed: causal sequence advances chronologically. Hence, if agent J can create the “divergence miracle”, he also can conduct an act that is itself the law-­‐breaking event against the chronology law of physics, and, thus, can break the laws in the strong sense. As in all possible scenarios where an agent breaks the laws in the weak sense, he also breaks the laws in the strong sense, and as we know breaking the laws in the strong sense implies breaking the laws in the weak sense, we conclude that the weak and strong definitions are similar. If we agree that weak and strong definitions are the same, Lewis’ argument against the validity of Inwagen’s consequence argument is problematic. To prove that Inwagen’s fifth premise is false in the strong sense, Lewis hints at the possible scenarios where the agent renders the conjunction of history and laws false in the strong sense, but breaks the laws in the weak sense. Because we have proved that breaking the laws in the weak sense implies breaking the law in the strong sense, such scenarios are impossible. Similarly, to prove that Inwagen’s sixth premise is false under the weak definition, Lewis refers to cases where, although the agent cannot break the laws in the strong sense, he can break the laws in the weak sense. As we have proved that breaking the laws in the weak sense leads to breaking the laws in the strong sense, such cases could not exist. Thus, all of Inwagen’s premises remain accurate.

Overall, this paper challenges Lewis’ distinction between the weak and the strong definitions of “ability to break the laws” by arguing that it is impossible to break the laws in the weak sense without breaking the laws in the strong sense. Consequentially, Lewis’ reasoning against Inwagen’s Consequence Argument, which relies heavily on the weak-­‐strong senses distinction, is problematic. This paper, thus, concludes that Inwagen’s proof for the incompatibility between free will and determinism remains valid.

Note: the terms “ability to break the law” and “divergence miracle” are used throughout the writings of Inwagen and Lewis. The author of this paper thus decide to not put footnotes beside these terms.