Ekstrom's Chapter 4 is titled "Varieties of Libertarianism." This is not, of course, libertarianism in the political sense, but in the philosophical sense. Ekstrom identifies three types of libertarian free will. She dismisses the first two, so I will not say much about them.
Type 1 theories - Free actions are uncaused.
The main problem with this approach is that, if my action is not caused by anything, then it is not caused by me, in particular. That seems to mean that it is out of my control.
Type 2 (agent-causal) theories - Free actions are not caused by any sequence of physical events, but by the agent who is acting. Here an agent is taken to be something that is not reducible to a physical description (in terms of systems of neurons, etc), but is a substance or entity in its own right. Chisholm says an agent is a "prime mover unmoved."
All this (it seems to me) has an uncomfortably religious ring to it. The agent is a sort of immaterial spirit that, in some unspecified way, is able to act on the material body to bring about actions. I gather from Ekstrom that these theories have, in fact, come in for some "heckling" from other philosophers. She points out three difficulties for agent-causal approaches:
- How can there be two different types of causation - agent causation and ordinary physical causation - interacting in a single human being?
- If an agent has no physical structure, then how can we understand the changes in the agent that bring about a free choice at a particular time?
- What evidence is there of a separate, non-physical, sort of causation?
Type 3 theories - A free action is indeterministically (or probabilistically) caused by a previous event involving an agent.
I will tackle Type 3 theories in the next post.