There is more here: Brains as output/input devices [...]

Although I should note that I believe there to be phenomena that qualify to be defined as 'free will'. Specifically endogenous processes generating behavioral variability and thus non-linearity. Especially if you can show that the complexity of transformation by which a system shapes the outside environment, in which it is embedded, does trump the specific effectiveness of the environmental influence on the defined system. In other words, mind over matter. You are able to shape reality more effectively and goal-oriented and thus, in a way, overcome its crude influence it exerts on you. For example, children and some mentally handicapped people are not responsible in same the way as healthy adults. They can not give consent or enter into legally binding contracts. One of the reasons for this is that they lack control, are easily influenced by others. Healthy humans exert a higher control than children and handicapped people. You experience, or possess a greater extent of freedom proportional to the amount of influence and effectiveness of control you exert over the environment versus the environment over you. Though this definition of free will only works once you arbitrarily define a system to be an entity within an environment contrary to being the environment. Thus the neural activity, being either consciously aware and controlled by the system itself, or not, is no valid argument within this framework. Of course, in a strong philosophical sense this definition fails to address the nature of free will as we can do what we want but not chose what we want. But I think it might after all be a useful definition when it comes to science, psychology and law. It might also very well address our public understanding of being free agents.