Interesting musings on free will from "Story of Your Life" by Ted Chiang - the novella upon which the film "Arrival" was based.
Was it actually possible to know the future? Not simply to guess at it; was it possible to know what was going to happen, with absolute certainty and in specific detail? Gary once told me that the fundamental laws of physics were time-symmetric, that there was no physical difference between past and future. Given that, some might say, “yes, theoretically.” But speaking more concretely, most would answer “no,” because of free will.
I liked to imagine the objection as a Borgesian fabulation: consider a person standing before the Book of Ages, the chronicle that records every event, past and future. Even though the text has been photoreduced from the full-sized edition, the volume is enormous. With magnifier in hand, she flips through the tissue-thin leaves until she locates the story of her life. She finds the passage that describes her flipping through the Book of Ages, and she skips to the next column, where it details what she'll be doing later in the day: acting on information she's read in the Book, she'll bet one hundred dollars on the racehorse Devil May Care and win twenty times that much.
The thought of doing just that had crossed her mind, but being a contrary sort, she now resolves to refrain from betting on the ponies altogether.
There's the rub. The Book of Ages cannot be wrong; this scenario is based on the premise that a person is given knowledge of the actual future, not of some possible future. If this were Greek myth, circumstances would conspire to make her enact her fate despite her best efforts, but prophecies in myth are notoriously vague; the Book of Ages, is quite specific, and there's no way she can be forced to bet on a racehorse in the manner specified. The result is a contradiction: the Book of Ages must be right, by definition; yet no matter what the Book says she'll do, she can choose to do otherwise. How can these two facts be reconciled?
They can't be, was the common answer. A volume like the Book of Ages is a logical impossibility, for the precise reason that its existence would result in the above contradiction. Or, to be generous, some might say that the Book of Ages could exist, as long as it wasn't accessible to readers: that volume is housed in a special collection, and no one has viewing privileges.
The existence of free will meant that we couldn't know the future. And we knew free will existed because we had direct experience of it. Volition was an intrinsic part of consciousness.
Or was it? What if the experience of knowing the future changed a person? What if it evoked a sense of urgency, a sense of obligation to act precisely as she knew she would?
...perceived the same physical world, but they parsed their perceptions differently; the world-views that ultimately across were the end result of that divergence. Humans had developed a sequential mode of awareness, while heptapods had developed a simultaneous mode of awareness. We experienced events in an order, and perceived their relationship as cause and effect. They experienced all events at once, and perceived a purpose underlying them all. A minimizing, maximizing purpose.
...The heptapods are neither free nor bound as we understand those concepts; they don't act according to their will, nor are they helpless automatons. What distinguishes the heptapods' mode of awareness is not just that their actions coincide with history's events; it is also that their motives coincide with history's purposes. They act to create the future, to enact chronology.
Freedom isn't an illusion; it's perfectly real in the context of sequential consciousness. Within the context of simultaneous consciousness, freedom is not meaningful, but neither is coercion; it's simply a different context, no more or less valid than the other. It's like that famous optical illusion, the drawing of either an elegant young woman, face turned away from the viewer, or a wart-nosed crone, chin tucked down on her chest. There's no “correct” interpretation; both are equally valid. But you can't see both at the same time.
Similarly, knowledge of the future was incompatible with free will. What made it possible for me to exercise freedom of choice also made it impossible for me to know the future. Conversely, now that I know the future, I would never act contrary to that future, including telling others what I know: those who know the future don't talk about it. Those who've read the Book of Ages never admit to it.