Libertarianism (metaphysics)
Libertarianism is one of the main philosophical positions related to the problems of free will and determinism which are part of the larger domain of metaphysics.[1] In particular, libertarianism is an incompatibilist position[2][3] which argues that free will is logically incompatible with a deterministic universe. Libertarianism states that since agents have free will, determinism must be false and vice versa.[4]
For other uses, see Libertarianism (disambiguation).
One of the first clear formulations of libertarianism is found in John Duns Scotus. In a theological context, metaphysical libertarianism was notably defended by Jesuit authors like Luis de Molina and Francisco Suárez against the rather compatibilist Thomist Bañecianism. Other important metaphysical libertarians in the early modern period were René Descartes, George Berkeley, Immanuel Kant and Thomas Reid.[5]
Roderick Chisholm was a prominent defender of libertarianism in the 20th century[6] and contemporary libertarians include Robert Kane, Geert Keil, Peter van Inwagen and Robert Nozick.
Agent-causal theories[edit]
In non-physical theories of free will, agents are assumed to have power to intervene in the physical world, a view known as agent causation.[14][15][16][17][18][19][20][21] Proponents of agent causation include George Berkeley,[22] Thomas Reid,[23] and Roderick Chisholm.[24]
Most events can be explained as the effects of prior events. When a tree falls, it does so because of the force of the wind, its own structural weakness, and so on. However, when a person performs a free act, agent causation theorists say that the action was not caused by any other events or states of affairs, but rather was caused by the agent. Agent causation is ontologically separate from event causation. The action was not uncaused, because the agent caused it. But the agent's causing it was not determined by the agent's character, desires, or past, since that would just be event causation.[25] As Chisholm explains it, humans have "a prerogative which some would attribute only to God: each of us, when we act, is a prime mover unmoved. In doing what we do, we cause certain events to happen, and nothing—or no one—causes us to cause those events to happen."[26]
This theory involves a difficulty which has long been associated with the idea of an unmoved mover. If a free action was not caused by any event, such as a change in the agent or an act of the will, then what is the difference between saying that an agent caused the event and simply saying that the event happened on its own? As William James put it, "If a 'free' act be a sheer novelty, that comes not from me, the previous me, but ex nihilo, and simply tacks itself on to me, how can I, the previous I, be responsible? How can I have any permanent character that will stand still long enough for praise or blame to be awarded?"[27]
Agent causation advocates respond that agent causation is actually more intuitive than event causation. They point to David Hume's argument that when we see two events happen in succession, our belief that one event caused the other cannot be justified rationally (known as the problem of induction). If that is so, where does our belief in causality come from? According to Thomas Reid, "the conception of an efficient cause may very probably be derived from the experience we have had ... of our own power to produce certain effects."[28] Our everyday experiences of agent causation provide the basis for the idea of event causation.[29]