" ... I'm talking an empirical definition of what freedom would mean .... "
It seems to me that the question "What is freedom?" isn't answerable by purely empirical means [
http://en.wikipedia.org/wiki/Empirical]. The question is intrinsically "normative," as philosophers call such things. [
http://en.wikipedia.org/wiki/Normative#Philosophy]
One could devise a somewhat empirical definition of freedom, but it would have highly limited utility, since it wouldn't apply to myriad important situations. This very limited construction would define freedom as "able to move about freely," basically, as in the case of any animal which either is in a cage or a trap -- or not.
The normative, or philosophical, question --What is freedom?-- is an ancient (and continuing) inquiry, and a good and important one. My own view is that there are better and worse responses to this question, and the better ones, I think, always involve the question of social justice. For it makes little sense to answer, "Freedom is the ability to do whatever the hell I want." Obviously, if my wants aren't in perfect accord with the wants of all others who will be in any way affected by the behaviors issuing from those wants, I can't consider
What is freedom? without considering these others and their wants and needs. So the very concept of freedom, I think, belongs to philosophical ethics. It is an ethical question more than an empirical one.
Considered ethically, my freedom isn't 100% about just me, but necessarily includes my life with others, and their freedom. I don't believe I can be optimally free if my neighbors are not also optimally free, and since so many of my neighbors (nearby or far away) haven't got optimal justice-dependent freedom, neither do I.
So, what is justice, then? Justice is basically fairness. It isn't fair for some people to do all of the work, or all of the dirty, dangerous, toxic work at little pay, while I or others "benefit" from their degraded condition. I'm thinking of the boy in India I saw in a online video, recently. He was very poor, and the only work available to him was holding bits of electronic waste (broken or obsolete computers, mostly) over a hot fire, while knocking components from circuit boards. He breathes toxic fumes all day while doing this, and the price he will pay in health is far, far too high for whatever meager benefit may come of his work. And here I am, typing on a computer. Proof that, though he's on the other side of the world, I'm in a kind of immediate relationship with him. he's far away, but nearby. Right at my finger tips. His unfreedom impinges upon my freedom, limits my freedom, or at least informs it. I cannot pretend that his freedom--or unfreedom--is unrelated to mine. I am only optimally free when everyone is. But that's an ideal, and isn't likely to ever be completely achieved. So none of us are quite free, really. We will be free when the world is a just--fair--place. No sooner. Or, put differently, we are free by degrees, little by little.... It is the road we are on, we hope.