Free will can usefully be considered a legal, rather than a physical, category; similar to what the law means by "in his right mind" or "competent to stand trial".
Upvoted for your good point. The legal definition is probably much more widespread compared to the common sense one that the others I considered in the OP.
1) I don't use the phrase at all except in discussions about paradoxical properties of the concept it usually denotes.
2) I don't think so for several reasons:
First, the problem of free will is an interesting topic for rationalist discussion but not an important matter of rationality. Belief in free will (whatever it means) hardly causes significant problems. It may be argued that belief in free will somehow makes people more prone to religion or mystical thinking, but my personal experience does not support that.
Second, "free will is a fallacy" is not well formulated. The philosophical arguments about free will are full of fallacies of different kinds, but free will itself is not. "Free will is an illusion" may be better.
Third, the proposed meme is too general to enhance rationality. Where exactly is the fallacy? To become more rational, we should have things explained, not memorise slogans. (When short rationality-promoting memes are needed, I prefer those formulated as commands rather than statements of fact. "Beware of mystical thinking!" "Do not create mental models around poorly defined entities!" "Make your beliefs testable!" Those properly internalised may immunise a person against free-will bullshit without creating a false impression that (s)he knows the answer to "What is free will?" - A fallacy, of course.)
3) I don't suggest using the word. Simply don't discuss it at all. The meaning of "free will" is context dependent and in some situations a common interpretation (usually the legal one suggested by RolfAndreassen) can be reasonably assumed. Even then there is no cost for using a less ambiguous phrase. I have been able to live without either abusing "free will" or declaring "free will is a fallacy" for many years. (I became a determinist when I was 12 or so, but have overcome the feeling of mystery associated with free will much later, essentially after reading Yudkowsky's articles. Meanwhile I was confused, compartmentalised a lot, and was feeling unconfortable discussing free will. Thus I tried to avoid that, and it wasn't difficult at all - "surprisingly" nobody wanted to engage me in debates about this topic.)
I find the concept of free will cumbersome and problem inducing in discussing ethics. People hide behind it, people name it and don't discuss it, I probably shouldn't have called it a fallacy, I'm just frustrated people namedrop it yet be completely unable to define what precisely it adds to the discussion or why it helps (I'm not talking about LW posters).
The legal meaning of free will seems better covered by the phrase "of sound mind".
Free will is an illusion
It seems I was holding the idiot ball when writing the phrase. I'm stealing this.
The OP title:How do you use the phrase "free will"?
I don't usually bother using it at all. The main ingredients of the feeling of free will — a planning and decision algorithm capable of considering counterfactuals, plus a huge dose of mind projection fallacy and non-reductionist confusion — are both interesting to talk about; but unless we're actually talking about that specific confusion and trying to overcome it, why the hell would we continue referring to the combination of the two with the same word?
(Though I'm willing to use it to refer to just the aforementioned planning and decision algorithm, if I'm talking to someone who I expect won't be confused by that.)
Is "Free will is an illusion" a rationalism enhancing meme?
No. That's a meme that promotes the idea that in "rationalism" lies despair and nihilism, instead of a better understanding of normality.
Plus, it's like saying that it's an "illusion" to suppose that a calculator is really performing addition when it is really nothing but a mere dance of electrons and transistors. If you even think to say "free will is an illusion", then you probably haven't seen through the confusion. (And you're certainly not going to help anyone else see through the confusion, if "free will is an illusion" is how you start the explanation.)
I think most people would agree that a dice, regardless it its fair or not, does not have free will simply because its unpredictable.
You've obviously never played pen and paper RPGs.
Usually I don't. If I do it's something like the capacity to follow whichever course of action is favored by a mental calculation of your preferences in absence of control through an other intelligence. Moral responsibility requires that a different assignment of moral weight in such a calculation would have resulted in a different course of action.
No. All uses of the phrase "free will" I ever encountered either described something real (in as far as abstract concepts can be real) or didn't make enough sense to call an illusion (the overwhelming majority).
People usually just mean that they could choose differently (which is true enough for a sensible understanding of "could"), it's only when they think about implications for other models for the outcome of that choice that the craziness shows up.
I think of free will as being the ability to make predictions and decide what to do based on those predictions. In other words, having free will means being a decision agent. I define it this way because the typical human feeling that we have free will exists for good reason, and I prefer to define free will in terms of what that feeling actually refers to, rather than having to tell people that their feeling of free will is wrong, when it isn't entirely.
The idea of "free will" probably best approximates "deliberate, unforced decision-making in a typical mental state", in the sense that someone who twitches doesn't do it of their "free will" and neither does someone who wanders miles away in a sudden fugue. On Newcomb's Problem, someone can be meaningfully said to have decided whether to one-box or two-box "of their own free will" even if Omega's ability to predict their action means that their decision wasn't uncausedly "free".
This especially the phrase "deliberate, unforced decision-making in a typical mental state" seems very similar to what I meant when I wrote "properly functioning brain".
I should have put more emphasis on the point in the second paragraph in conjunction with question two a bit more. Perhaps we can, even in moments of sloppy thinking, shed inappropriate cached thoughts and get a good and intuitive definition of free will but how long would we need to explain for example the above formulation rather than just explaining to someone in what way "free will" is a fallacy.
Question 2. might be reformulated as: Will spreading this meme raise the general sanity waterline?
Isn't "you" a fallacy in essentially the same way that "free will" is? But it, like free will, can be a rather useful shortcut.
Q1. I wouldn't introduce the phrase, and would want to know what anyone else using it intended by it before there could be a useful conversation. There's too much variation in what people who talk about free will consider themselves to be talking about to get anywhere without unpacking it first.
Q2. Given that variation, "free will is an illusion", unexpanded, is no more than slogan, rather than a meme, and one of nihilism, not rationalism. The purpose of saying it is disempowerment; the one saying it is seeking power over other people. "You do not exist," said O'Brien to Winston Smith, and "free will is an illusion" is pretty much the same thought.
I define free will in an unusual way, which I find to be the most general concept that serves a number of related purposes. This is only defined with respect to a given level of intelligence. For example, something with behaviour that can be completely predicted by an intelligence has no free will with respect to that intelligence, since it is pointless to talk about what it `could' do; there is only one known thing that is possible. Also, if a system does not make computations about the properties of various outputs that are too complex to predict before choosing one, I would not say that it has free will, just that it's output is uncertain. In some ways, this is the same definition of possible, but the distinction is useful for thinking about my own free will and discussing others' free will with them, including in decision theory contexts.
Recommended for 1): http://lesswrong.com/lw/of/dissolving_the_question/
@2: I do not think so. Sounds too much like name-calling. Given a few minutes of time, however, an explanation like given above should help.
@3: With people with whom I discuss free will, I do no lie, I spell out my position. WIth others, I do not lie, I do not discuss it. And I think it is not all too important for me that my grandfather get's a philosophy 101 course.
I first wanted to write out a short paragraph about free will as it is used by most people, being just plain wrong. The universe is in a very real sense deterministic after all, even if God does play dice. I think most people would agree that a dice, regardless it its fair or not, does not have free will simply because its unpredictable.
But I quickly admonished myself since I realized very few if any LW posters need reminding of this on a theoretical level. And certainly the majority of LWers who use the phrase don't use it in the same sense its understood by most people. But despite this theoretical understanding I've noticed that I often slip up unless I pay attention since, gosh it sure does feel like I have free will and this it seems is my default mode of thinking, I also noticed some other posters slipping up on this.
I especially recall a recent commenter discussing whether some criminals should be denied cryogenic suspension contrasting "mental illness" to "free will". That irked me slightly since mental illness is, like all illness, defined as what people in a society decide is unintegratable into it (a secondary but common feature is that it is a state that is nearly universally determined by those who are in it as undesirable, understandably this is less often true for "mental illness" than "physical illness")!
So even if one uses or defines free will as a "properly functioning brain" or "proper socialization" it would still be just so much better if he had said "only those with criminal behavirours that are very damaging to others and which we think will be unfixable even in the distant future shouldn't be suspended because we don't have unlimited resources and its better to focus on those the future is more likely to help first".
My questions are:
1. The OP title:How do you use the phrase "free will"?
2. Is "Free will is an illusion" a rationalism enhancing meme?
3. If you disagree with 2. why "lie" to people by arguing using a word in a way they will almost certainly misunderstand? Do you think more people intuitively share the proper meaning of the phrase than I have assumed?