- Why Free Will Is Real by Christian List
In accessible and informal prose, this book defends the view Christian List names "compatibilist libertarianism." Almost every key argument relies upon three foundational ideas. One is the naturalistic ontological attitude, which asserts that the phenomena described in our best sciences really do exist. Hence, if the best theories of physics say that there is an electron, we ought to think it exists. The other two, which are emergent levels and multiple realizability, are closely linked. Higher levels supervene on lower levels, and of particular interest here is the level of intention, which supervenes upon the microphysical level. At a higher level, certain phenomena may be found that are not found at a lower level. Furthermore, the same higher-level phenomenon may be able to be realized in a variety of ways by the lower level—for instance, the belief that Washington, D.C., is the capital of the United States could be correlated with many underlying neurological states.
In the first chapter, List describes his "fairly commonsensical" notion of free will as a threefold capacity, which allows the agent to act intentionally, with access to alternative possibilities, along with control of one's actions. In the second chapter he explains how intentional agency is threatened by reductive materialism, alternative possibilities by determinism, and control of one's actions by epiphenomenalism. These criteria and challenges for free will serve as the structure of the remaining chapters.
In chapter 3, List argues that intentional agency supervenes on the physical but cannot be reduced to the underlying physical states. For one phenomenon or term to be reducible to another, it would have to satisfy two conditions. It cannot merely be "necessarily co-occurrent," but must furthermore be able "to serve as a substitute for the higher-level property in scientific discourse." In the case of the intentional states of an agent, there are two reasons why the second condition does not obtain. First, the "aboutness" of intentional states, along with the rational, semantic, and logical, are not equivalent with physical properties. Second, intentional states seem to be multiply realizable.
The fourth chapter argues that even if we assume physical determinism, it is not logically permissible to make the jump from physical determinism to agential determinism. Physical determinism could give rise to a higher level, the level of agency, which is indeterministic. In fact, in theory a world with indeterministic physics could give rise to an emergent agency that itself unfolds deterministically. Hence, the determinism to which the physical sciences bear witness cannot be a reason for determinism at higher levels. In fact, all of our best scientific theories that have something to say about agency—such as psychology or economics—require an openness to alternative possibilities. Regardless, then, of the determinism or indeterminism at the microphysical level, we should accept that, in a modal sense, there are alternative possibilities at the level of agency.
Of course, even if the level of agents, where alternative possibilities are located, is indeterministic, there remains the question of how it is that intentional states cause the agent's actions on a lower level, which is the [End Page 374] topic of chapter 5. Together, the causal closure of the physical world—"any physically realized effect has a sufficient physical cause"—and the causal exclusion principle—"if an effect has a sufficient physical cause, then it does not have any other, distinct cause occurring at the same time"—appear to rule out mental causation. However, when an understanding of causation as difference-making is joined to the concept of the multiple realizability of higher-level states, there is every reason to reject the causal exclusion principle. For even though the microphysical state of the brain is part of the explanation of why a taxi driver takes me to St. Pancras, the difference-making cause is found at the level of intention. There can, in fact, be an explanatorily necessary higher-level causes simultaneous with the physical causes: despite the fact that mental states supervene on physical states...