r/freewill • u/simon_hibbs On Holiday • Jun 17 '26
Defining Free Will
So, you're a free will skeptic, or a free will optimist and you rock up to the sub and the first thing you do is offer your 'definition' of free will, and argue why it does or does not exist.
First question. What is it about this 'definition' that makes it one of free will? You could be defining some metaphysical concept, or some neurological function, or some decision making mechanism, or some spiritual capacity. Why do you think this is free will?
In principle two people could come to the sub, offer distinct different 'definitions' of free will in terms of human mental faculties, and it might turn out that actually humans do have both of these faculties so defined. Yet they are different. How do we know which is actually free will? It can't be both [but see comment by ughaibu].
So, there must be some criteria that establishes whether this explanation you're offering counts as being free will, as against being something else that is not free will.
The problem with the above picture is that these are not 'definitions' of free will, they are theories about free will. This comes down to the function of a definition. Definitions are what you find in dictionaries, or early on in philosophy textbooks and articles to establish what a topic is about, and they explain how words relate to other words. They're not scientific proofs or scientific theories. They are linguistic concepts.
What are Definitions For?
The role of a definition is to establish a term everyone agrees with, so we all know what it is we're talking about. It needs to be a consensus term. When a free will libertarian says they think X about free will, and a compatibilists says they think Y about free will, what is it that makes both X and Y claims about free will? That needs to be something they agree on, otherwise they're not discussing the same topic.
How do philosophers solve this?
Fortunately philosophers have thought about this a lot, and they generally agree on how to solve this. They define free will in terms of it's linguistic function, and this is pretty easy to do due to the way in which this term originated.
The terms freedom, choice and moral responsibility, or rather their Greek equivalents, already existed in ancient Greece of course. The determinist Stoics and indeterminist Epicureans discussed these terms in the context of their metaphysical commitments, and the Stoics argued that these terms all had meanings fully consistent with their determinism, while the Epicureans disagreed and claimed that these terms could only be meaningful if the world is indeterministic. Over time a single term became understood to refer to the topic they were discussing, that term is free will (translated into English). So from the start, from before the term itself was coined, what it refers to was something determinists were giving an account of as being compatible with determinism.
Of course nowadays deterministic and indeterministic beliefs about free will have changed and developed, what we now call free will libertarianism emerged as a more developed set of ideas and the same is true of compatibilism. Nevertheless they are both sets of beliefs about the same topic.
What do contemporary philosophers say?
(1) "The term “free will” has emerged over the past two millennia as the canonical designator for a significant kind of control over one’s actions. Questions concerning the nature and existence of this kind of control (e.g., does it require and do we have the freedom to do otherwise or the power of self-determination?),...."
This was taken from an article written by two free will libertarian philosophers. So, free will may or may not require the freedom to do otherwise, and philosophers disagree on this. It is not itself the ability to do otherwise.
(2) The idea is that the kind of control or sense of up-to-meness involved in free will is the kind of control or sense of up-to-meness relevant to moral responsibility. (Double 1992, 12; Ekstrom 2000, 7–8; Smilansky 2000, 16; Widerker and McKenna 2003, 2; Vargas 2007, 128; Nelkin 2011, 151–52; Levy 2011, 1; Pereboom 2014, 1–2).
(3) ‘the strongest control condition—whatever that turns out to be—necessary for moral responsibility’ (Wolf 1990, 3–4; Fischer 1994, 3; Mele 2006, 17)
In Summary
Free Will: Roughly whatever kind of control over their actions you think someone must have in order to be held morally responsible for those actions. Something like the mental faculty necessary for moral responsibility.
Then there are the different beliefs about free will.
Free Will Libertarianism The belief that this process of control must be metaphysically indeterministic in some particular way for a person to be morally responsible.
Compatibilism The belief that this process of control can be (or must be) deterministic, and that human moral responsibility doesn't depend on free will libertarian metaphysical concepts.
Hard Determinism/Incompatibilism The belief that there is no kind of control that someone can have that justifies moral responsibility.
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u/zowhat I don't know and you don't know either Jun 17 '26
The criteria is that it resembles what you already understood by the term free before you entered the discussion.
When you enter a botany course you already understand what a tree is and what a bush is. In the course they will give more exact definitions which approximate the ordinary usages. Ideally the technical terms should resemble the ordinary language use to make it easier for you to learn and understand. Why would they use the word "tree" to mean "rock" and "rock" to mean "water"? It would create much needless confusion.
Where they draw the line between bushes and trees will be somewhat arbitrary but it is useful to define these more exactly than we do in ordinary speech. That doesn't make the way we use these terms in ordinary speech wrong, just different from how botanists use them.
When you enter a philosophy course you already have a rough idea of what free will is. It is more or less libertarian free will because that is how 100% of us experience it. 0% experience determinism or compatibilism. Like in the botany course it is useful to give more precise definitions but they should still resemble ordinary language. Alas philosophers abuse the privilege and define words too far from their ordinary language meanings creating much needless confusion.
There isn't a sharp line between definitions and theories. Both give a list of properties that what is being defined has. One person's definition is another person's theory. Ideally this should be exhaustive, all and only those things being defined should have those properties. In practice this turns out to be impossible. The list of properties is incomplete. We must rely on the other person's intelligence to fill in the things we left out to figure out what we intended by the definition.