Free Will, Determinism, and Time Travel Fiction

DC Iris Maplewood discovers one of the titular bodies in Netflix's Bodies

Something about science fiction makes writers feel compelled to break down the story’s speculative core somewhere around the halfway mark. Though Obi-Wan Kenobi introduces Luke to the Force early, halfway is when he explains its principles of mindfulness and flow. Similarly, though Kyle Reese has introduced Sarah Connor to his dystopian future, only around the halfway mark does he explain it to Dr. Silberman in any detail. Same applies to Netflix’s recent limited series, Bodies.

In episode four (of eight), the breakdown comes in two increments. First, we witness physicist Gabriel Defoe’s (Tom Mothersdale) lecture summation, describing the hypothetical Deutsche Particle, which simultaneously exists forward and backward in time. Later, speaking privately with Detective Constable Iris Maplewood (Shira Haas), Defoe extrapolates that, if the future already exists, free will is illusory. Maplewood demurs. Though structurally, Bodies is a police procedural, this science fiction rumination of liberty drives the series premise.

Recent philosophy has seen the resurgence of a previously endangered idea: determinism. Medieval Thomist philosophy contended that everything which happens in the material world has a prior cause. Yet every cause is, itself, an effect of a prior cause. Thus, reality exists in a causal chain descending through history to what Thomists call the First Cause. As Christians grounded in Aristotelean philosophy, Thomists correlated this First Cause with God, who set all reality in motion.

Determinism, this belief that all reality was set in predeterminate motion at the moment of creation, came under conflict during the Reformation, when many reformers contended that humans have the capacity, within our sensory limits, to accept or reject God. (Replace “God” with “philosophy” if that streamlines your thinking.) Reformers called this capacity “free will.” By the Enlightenment, free will became the operant European philosophy, mutatis mutandis, and arguable remains so through to the present.

Free will has recently come under fire from prominent atheists and sceptics. John Gray and Sam Harris are probably the most prominent, but an entire subthread of philosophy of science contends that free will is an illusion. Because our choices are conditioned by outside events and circumstances, most of which we cannot possibly comprehend, choice therefore isn’t real. (It’s more complicated than that, but bear with me.) This philosophy has limited traction outside narrow circles.

Sarah Connor (Linda Hamilton) and Kyle Reese (Michael Biehn)
near the culmination of their journey, in The Terminator

Okay, our choices are conditioned; anybody who’s had a job or otherwise interacted with complex human society will accept this. But to what degree are our choices determined? Philosophers consistently fail to close this gap. In Bodies, Defoe himself leaps that gap, even within himself; though he argues verbally that our choices are determined, we discover, eventually, that he attempts to change their conditions. (No spoilers; this is about Bodies’ philosophy, not its story.)

In the early seasons of the resurrected Doctor Who in the mid-2000s, the Doctor avoided intervening in history with two arguments. Sometimes he couldn’t revisit preceding actions, claiming that “we’re part of events now.” (This was mainly the Tenth Doctor, who couldn’t stomach contradictions or paradox. The Eleventh Doctor actively sought paradox.) Other times he claimed “a fixed point in time,” something so important that, even if it was terrible, intervening would create something far worse.

James Cameron’s first Terminator movie ends withSarah Connor’s realization that, though she and Reese defeated the monster, the monster’s creation was inevitable. Time, in the first movie, is circular, and attempts to alter it instead create it. But Cameron couldn’t stomach that forever, and reversed himself in the second movie. History can change; no fate but what we make. Cameron, like Bodies, initially accepts that we’re trapped in a causal loop, but finally resists such fatalism.

Thus, time travel fiction manifests a recurrent theme: history is contingent, without necessarily being inevitable. Just because events occurred in a certain way, doesn’t mean they had to occur that way. We cannot always know what contingencies define our actions, and some contingencies we can never know. Yet that doesn’t mean our choices are determined. Humans aren’t inevitable products of physics. We have the unique capacity to pause, think, and change our minds.

Bodies is, essentially, an allegory of the human capability to change our minds. Professor Defoe’s lecture on determinism stems from the assumption that, because time exists both forward and backward, the entire past and future already exist in fixed forms. But DC Maplewood realizes, as James Gleick has written elsewhere, that the laws of physics are a description of reality, not reality itself. We can accept our contingencies, she reveals, without our contingencies owning us.