We need to bear this in mind throughout our discussion. If causality is contradicted (which it's not), then my argument for free will is flawed (which it could be anyway . . . but you'll need to persuade me).
With that background, I think the greatest difficulty in understanding self-determinism as free will is the notion that we CAUSE our actions. That is NOT the case. What we need to appreciate is that, because causality is usually a chain-reaction of events, cause and effect are relative and depend on perspective. For instance, one could say that 65 million years ago, a global die-off of dinosaurs was caused by the impact of a huge meteor in a Mexican peninsula. But we could also describe the cause by going back a step and claiming that the global die-off was caused by a collision of huge meteors in the meteor belt that sent one of them ricocheting to Earth. With that perspective, the collision of meteors was the cause -- and impact with Earth was the effect.
Now, let's apply true causality to the human brain.
Consciousness is NOT "all in the head" -- it is the interaction of our brains and sensory organs with the world around us. If any 1 of these 3 components NEVER existed, there could be no consciousness. Please don't confuse that assertion with cases in which consciousness existed but was lost or obscured due to injury or illness. In such cases, experience has had a chance to inform our brains. My particular claim is that if we NEVER had a brain or sensory organs or a world around us (or any combination thereof), there could be no experience to be informed or conscious of.
But once we ARE conscious, we soak up experience like a sponge. This would not be possible without feedback mechanisms in the brain. Without feedback, we could not retrieve memories or entertain thoughts or weigh experience. Without feedback, everything from the outside world would pass through us like light through glass.
Feedback is not only key to consciousness, it's also key to free will. Feedback allows us to anticipate and analyze causality and the world around us. Science has yet to discover any direction for time except forward. This means that causality can only unfold in the present. Mental feedback, by allowing us to anticipate the future, gives us a crucial, temporal, advantage over causality (which I'll develop, below).
Intelligent humans beings use this temporal advantage as naturally as a fish breathes water. It's virtually impossible to disassociate the future from human actions. Everything we do anticipates the future: whether that be half a second or half a century from now.
Causality exerts its influence on EVERYTHING. But, when it comes to animate beings, causality is merely an influence -- it's not a controlling factor. It is INANIMATE matter -- not animate beings -- that is controlled by causality. Inanimate matter has just one possible reaction to any event. But animate beings have VARIABLE POTENTIAL REACTIONS to any event. Animate beings are NOT physically predictable in the same way that inanimate matter is. This distinction between the <i>modes of response</i> by inanimate matter and animate beings is important when considering causality and free will. It's the difference between a rock and a human.
Despite the fact that other animals appear to have consciousness and even some modest intelligence, I'll be limiting my explanation of free will to humans.
Please keep that in mind: free will, like consciousness, is a product of, and is dependent on, causality -- not an independent, spontaneous, dualistic, cause unto itself.
Causal factors are those parts of causality that affect specific events and/or our (re)actions. Heredity, intelligence, reflex, instinct, memories, experience, ethics, education, plans and ambitions are causal factors we acquire at conception or over time. Stimuli and events from the world around us, on the other hand, are real-time; in the present. In our interaction with the world around us, mental processing is the last step before action. Our brains contain all the causal factors we were born with or built up over time. They factor into our actions, as applicable to the situation. Mental feedback is the real key to free will which, like the world around us, operates in real-time; in the present.
This is how the interaction of our brains with the world around us PRODUCES free will. It's not the free will of unbridled liberty. It's the free will that leads us into futures of our own choosing. We have evolved to be self-aware and future-aware. Why would that be true, if not to enhance our survival as intelligent beings?