To repeat my criticism, I don't think "free will" means "causally unconstrained." I don't see how it is possible for the human brain--the apparatus of human volition--to step outside the causal flux. That ability, as Harry Frankfurt points out, is a question of power, not freedom. Humans are not omnipotent. We are finite, causally bounded creatures. Consequently, we are unable to step outside the system.
Pretty much every point of this argument is problematic, from the unanalyzed ambiguities of the phrase 'causally unconstrained' to the notion of the brain as 'the apparatus of human volition' to the extraordinarily vague 'causal flux' to the assumption that causal non-constraint implies omnipotence or stepping outside the system. Obviously something can be causally unconstrained in a number of very different ways; the brain is the 'apparatus of human volition' in pretty much the same way everything else about us is, and we might as well call our toes or our lungs the apparatus of human volition; by 'causal flux' he seems to mean 'things happening according to causal laws', which is useless unless the particular causal laws in question are specified; and obviously something may be causally unconstrained in one way but not others (and therefore not omnipotent); and input into a system is not 'stepping outside the system', even if it were an input of new initial conditions, and talk of such a thing is useless in any case unless you specify the system in question. But what I find more interesting is what he intends to put in its place:
So for me, free will isn't about causality. It is, rather, more akin to what we might call political freedom. Emancipation.
There are two aspects, positive and negative, related to this notion. The first is a negative. If I lock you up in a jail you are not free. If I let you out you become free. Freedom here is liberation, a freedom from....
If being released from jail is an example of negative freedom, freedom from the jail, then education is a good example of positive freedom, freedom to.
For example, one of the reasons we educate ourselves and our children is to increase our opportunities, to increase our choices. We become free to do this or free to do that. Thus, we become more free with education. Our horizons expand. We have greater knowledge and skill. As they say, "Knowledge is power." That power is the expansion of choice. What was once closed to us is now open. Less a freedom from than a freedom to.
The problem, of course, is that this is all just about ability and power, too. When I say that I am free from prison, what do I mean? I mean that prison and the causal factors associated with are not constraining me. I step outside the prison system. When I say that education frees me, what do I mean? I mean that education removes an impediment to my causal capacity. 'Horizons' don't expand in one direction, but in many different directions, any one of which you can go. If you can't actually go in all those different directions, your horizon hasn't expanded at all. If your choice is not choice from set of alternatives to no one of which you are causally constrained, your choices do not increase, they merely become different. And only if you are causally unconstrained with respect to this can you actually do this or do that; if something causally constrains you to do this, there's really no good pretending that you can also do that.
Thus political freedom, both positive and negative, is as much a form of being causally unconstrained as any other freedom we might have notions of; reject causal non-constraint, you empty political freedom of any positive meaning. You can still have negative freedom, which depends on a purely relative notion of causal non-constraint: a leaf that is falling is no longer constrained by the particular forces that held it to its branches. But positive freedom requires that we actually have options, and that requires that we are not actually constrained by any of our causes to only one possibility. Beck is quite right when later he associates skill and freedom and says, "the greater the skill the greater the freedom." That is a very medieval Aristotelian point; but, of course, there is a connection between greater skill and greater freedom due to the fact that you are less constrained to one thing the more skillful you are. Knowledge, technical skills, and virtues like prudence or justice open up options by closing down things that close down options. What Beck is really trying to do is have his cake and eat it, too: having a robust positive notion of freedom (greater horizons, expansion of choices) while denying the precondition for this. A consistent compatibilist would usually avoid this by reworking what is supposed to count as the positive notion of freedom so that it doesn't involve these things, but Beck seems to want to have it both ways.
What is happening, of course, as is made explicit in some of the comments to the post, is that Beck is asking one question: "Are human beings finite, physical, causally bounded creatures?" And the answer to this, obviously, is yes: hence his repeated denunciations of the straw man position that we are omnipotent. But this answer has no intrinsic connection with most of the conclusions Beck draws from it, unless you equivocate on the meaning of 'causally bounded', 'finite', and 'physical'.