Many discussions about human free will often find themselves mired in confusion. Much of the difficulty stems from the fact that the phrase “free will” itself can mean different things in different contexts. In particular, philosophical and theological debates over free will tend to take place on related but nonetheless very different semantic territories.
Here are some different basic descriptions of free will we will discuss:
Causal free will: more commonly known as “libertarian free will,” the ability to make a decision whose outcome is in some sense independent of the causal history of the universe, i.e. to have one’s deliberations be uncaused by any factor outside one’s own will.
Theological free will: the ability to make a decision whose outcome is not predetermined or preordained by a theistic deity, i.e. God.
Logical free will: the ability to make a decision whose outcome is not restrained by the truth value of given propositions concerning the future.
A large, but not all-inclusive, part of debates about free will is determining which, if any, of these or other formulations of free will must be descriptive of the situation in order for “true free will”--what I will refer to as free will simpliciter--to be present. If a given formulation doesn’t hold in a situation, we say that the situation is deterministic in regards to that formulation. Thus we can have causal determinism, theological determinism (predeterminism), logical determinism, and so forth.
To hold that a given formulation of free will need not be descriptive of a situation in order for free will simpliciter to be present is to hold a position called compatibilism. For example, some Calvinists are compatibilists in that they believe that humans can have free will despite their actions being in some sense preordained by God, while I, as well as most professional philosophers, are compatibilists in that we believe that human free will does not require human decisions to be physically uncaused by natural antecedents.
Contrariwise, to hold that a given formulation of free will must be descriptive of a situation in order for free will simpliciter to be present is to hold to incompatibilism. To be incompatibilist in regard to causality, for example, means that one believes that either causal determinism is false (allowing libertarian free will to exist) or else human beings do not have free will. Theologically, some Calvinists are incompatiblist in that they deny the existence of human free will, while Arminians and Catholics are similarly incompatibilists in that they reject the doctrine of predestination.
One might, quite reasonably, conclude that these debates are largely about semantics. Unless free will simpliciter exists somewhere as a form in a Platonic heaven, then this is only really a debate about how we, as language-users, ought to define the morpheme pair “free will.” To a large degree, this is correct. That is not to say, however, that all definitions are created equal. It is certainly not to say that all definitions match equally well with our intuitive understanding or ordinary use of a given phrase.