@Fil Albuquerque,
I don't know. All I know is that denying the mind and agency leads to logical paradoxes galore. So let's agree with McGinn that it's one of the stuff that exists in this universe. From there, it follows that it can be the cause of other stuff, other phenomena, and that it can be caused be pre-existing conditions or phenomena. That causation is never perfectly deterministic in my view. Given that a high complexity in things tends to make them more unpredictable than simpler stuff, it seems reasonnable that we are a sort of "concentrate of unpredictability". Now of course you will tell me that you don't author your own randomness, and I would disagree. You can also tell me that we don't own our logical reasonning and I would once again disagree. We ARE our thoughts, our logic, our ideas. That's us, that's what we are made of. Whether we can control our inspiration, our ideas, or our train of thoughts, is not relevant. We are "free" precisely because we are partly determined by our own chance and our own thinking, and our own choices.
To follow once own law is freedom, in the sense that it is freedom from somebody or something else's law. And therefore the mind's capacity to follow its own route and imagine all sorts of stuff and plan ahead and discipline itself somewhat to do the planned stuff, based on its own reasoning, that capacity is what I call freedom. Obedience to once own laws.