You've fairly demonstrated that humans have the ability to will, but in no way have shown that that will is not deterministic. And I don't mean deterministic in a neurological sense. Part III, like viruses, bears no relevance to the question. I'm talking about deterministic in the realm of the mind, the abstract whole of a neurological network.

We are not like a virus or a bacteria, reacting in a mechanically predictable way to a given environmental change, and having only a limited, enumerable number of possible reactions to such changes. On the contrary, human beings are not mechanically predictable (as Part III argued); and we possess an almost infinitely vast array of possible actions open to us.

Mechanical behavior bears no relevance. An enumerable number of possible reactions is only as enumerable as the actions that precede them, in this case the actions that played out in the mind. But 'enumerable possiblities' are useless speculation when we consider the fact that there was one and only one reaction. Something happened in the mind that resulted in that specific reaction, an unmeasurable compilation of instinct, memories, and sensory input in all their subtleties, subtleties that may elude consciousness itself resulting in the illusion of free will.

If that agent is sufficiently intelligent to perceive patterns in its own behavior, it can then recognize which of its own traits are contributing to poor outcomes, and turn this evidence into a new inclination toward changing those traits. Over time, such an agent can end up with a very different, and genuinely self-chosen, set of inclinations than the one they started out with. And even if an agent does not reflect on or change its own behavior, so long as it has the ability to do so, we can still rightly say that its current character is in a sense self-chosen, and that they are therefore responsible for it.

Pattern recognition comes in primitive forms that are hardwired into our brain, while other forms are learned through experience. Both of these are hence, deterministic. What prompts an agent to reasess it's "inclinations" and arrive at a self-chosen character is equally deterministic. If being mean to people results in a pattern of people being mean to me, I will naturally dislike being a societal reject, and modify my behavior accordingly. I can't think of any instance where a person lacks a prompt to change, not matter how subtle the combination of instinct, suppressed memories, or sensory input.

A necessary consequence of all this is that, if you cannot reflect on your own behavior, you don't have free will. Higher-order thinking - thinking about thinking - is a necessary precondition of this ability.

Are you insinuating that a baby doesn't have free will because it cannot reflect on it's own behavior, further implying that free will is learned? 'Thinking about thinking' simply boils down to thinking. We think what we think for a reason, no matter how subtle, as I've said, the combination of instinct, suppressed memories, or sensory input. Use your imagination, and you will quickly see this point.

We cannot magic our own characters out of the void. The truly "self-made" person, the one who bears ultimate and sole responsibility for every aspect of their own character and therefore bears ultimate and sole responsibility for every act they carry out, is an impossibility. But we can approximate this ideal sufficiently closely that we can, indeed, be said to make genuine choices and to bear the responsibility for those choices. In every way that matters, we are "free enough".

At your fuzziest, I completely disagree with you. You've only demonstrated that humans have the ability to will, and with something as vague as "free enough," have only succeeded in confirming my conviction that free will is an illusion.

On a tangent, does a compulsive liar or an addict possess free-will?

The bolder on a cliff was not mechanically predictable either. Neither is a pencil on its tip. And the pencil has an almost infinite number of orientations it can fall in. So we don't seem different in that way.

I acknowledge the point here; but I still think there's a relevant difference. After all, even if the specific details vary, the pencil or the boulder's next "action" is broadly determined in a mechanical sense by features of their immediate environment. Human beings are not like that. Inanimate objects generally have only one "path of action" open to them, in a sense, but we have a comparatively vast array of options, and our choice is determined not just by immediately present environmental causes but also by past information and by our own tendencies and dispositions.

For example, I play several first person shooter games. The monsters I shoot at "see" the bullets coming at them and they try to dodge them. Do they have free will? After all, they used their "world" knowledge to anticipate and react.

I don't think this is the same thing. The NPCs in a video game are not genuinely conscious of anything - they react because they are programmed to do so in response to certain input. Their "actions" are entirely controlled by immediate environmental causes, more like the pencil or the boulder than a human being. To use the philosopher's term, they are zombies. Only a being that possesses consciously experienced qualia - true sensory impressions of the world, however limited - can assemble them together into an internal world model that decisions can be based on.

On the contrary, human beings are not mechanically predictable (as Part III argued); and we possess an almost infinitely vast array of possible actions open to us.

The bolder on a cliff was not mechanically predictable either. Neither is a pencil on its tip. And the pencil has an almost infinite number of orientations it can fall in. So we don't seem different in that way.

In making it, something altogether new emerges, and that something is this: an ability not just to react blindly, but to anticipate - to build a mental model of the world in one's head, and to use that model to guide one's actions.

I am not sure if I agree with this. For example, I play several first person shooter games. The monsters I shoot at "see" the bullets coming at them and they try to dodge them. Do they have free will? After all, they used their "world" knowledge to anticipate and react.

A necessary consequence of all this is that, if you cannot reflect on your own behavior, you don't have free will. Higher-order thinking - thinking about thinking - is a necessary precondition of this ability.

This is something I need to think about. It shows a higher process that we have and does seem to link to what we think about whan we talk about free will.

Just some constructive criticism, since few seem to have much to say about it.