Christopher: Most neuroscientists who say free will is an illusion are asking the wrong question. They’re looking for a ghost in the machine. But what if the freedom we’re looking for isn’t in a ghost, but in the machine’s 4-billion-year-old source code? Lucas: Whoa, that's a heck of an opening. You're saying the debate isn't about soul versus brain, but about evolution? That feels like a total reframing of one of the oldest questions in philosophy. Christopher: It is. And that's the provocative argument at the heart of Free Agents: How Evolution Gave Us Free Will by Kevin J. Mitchell. Lucas: Right, and Mitchell isn't a philosopher sitting in an armchair. He's a neurogeneticist from Trinity College Dublin, which is a crucial detail. He’s tackling this ancient philosophical problem not with abstract thought experiments, but with biology, genetics, and a deep evolutionary story. Christopher: Exactly. And his approach has created quite a stir. The book earned starred reviews and has put him in direct, very respectful, public debates with prominent skeptics like Robert Sapolsky. Mitchell is really trying to naturalize agency—to show it’s a real, physical, evolved thing, not some spooky add-on. Lucas: I love that. Taking it out of the clouds and putting it into the cell. So, where does this four-billion-year story of free will even begin? I'm guessing not with a human agonizing over their morning coffee. Christopher: Not even close. To find the root of agency, Mitchell argues we have to go all the way back to the simplest life forms. Lucas, when you think of 'choice,' what's the simplest creature you imagine making one? A dog? A fly? Lucas: I guess a fly. I see one buzzing around, it seems to 'decide' to land on my sandwich. But even that feels like a stretch. A bacterium? No way. That's just a bag of chemicals reacting to stuff. Christopher: And that’s the first assumption Mitchell wants us to question. He argues that a single E. coli bacterium is already a tiny, primitive agent making choices.

Lucas: Okay, hold on. You're seriously telling me a bacterium has a form of free will? That sounds like a huge stretch. Isn't its movement just a series of pre-programmed chemical reactions? Christopher: It is, but the key is how that program works. It's not just a simple reflex. Imagine an E. coli in a petri dish. It's looking for food. It can't see or smell in the way we do, so how does it find the good stuff? It engages in this beautiful little dance: it swims in a straight line for a bit—that's the 'run'—and then it randomly stops and tumbles, pointing itself in a new direction before running again. Lucas: So it's just moving around randomly until it bumps into food? Christopher: Ah, but it's not purely random. This is where the agency comes in. The bacterium has sensors on its surface that detect sugar molecules. As it swims, it's constantly taking measurements. It's comparing the concentration of sugar now to the concentration a moment ago. Lucas: It has a memory? Christopher: A very simple, short-term one, yes! If the sugar concentration is increasing, it suppresses the 'tumble' and keeps running in that direction. It thinks, "Hey, I'm on the right track!" But if the concentration decreases, it's more likely to tumble and try a new direction. It's not just reacting to the present; it's making an inference about the world based on information gathered over time. It's making a goal-directed choice: move toward what helps me persist. Lucas: Huh. So the choice isn't "sugar or no sugar," it's "is this path getting better or worse?" That's… surprisingly sophisticated for a microbe. Christopher: Exactly. And it gets more complex. Mitchell talks about the Paramecium, that little oblong creature covered in cilia. If you poke a Paramecium in the front, it has a specific avoidance reaction: it reverses, turns, and moves forward in a new direction. But if a predator bumps it from behind, it has a different reaction: it just speeds up to escape. Lucas: So it's not a single "danger!" reflex. It's a context-dependent decision. "What kind of danger, and from where?" Christopher: Precisely. The organism is integrating multiple streams of information to select the most appropriate action from a repertoire of possible actions. This, for Mitchell, is the absolute bedrock of agency. It's a physical system, configured by billions of years of natural selection, to do things for reasons. The "meaning" of a sugar molecule is "good, approach." The "meaning" of a poke in the rear is "danger, flee." The purpose is always the same: to continue existing. Lucas: I can see the seed of it now. It's not about consciousness or deep thought. It's about a system being organized in a way that it can act on its own behalf to further its own goals. But that's still a massive leap from a Paramecium avoiding a predator to me deciding whether to ask for a raise or quit my job. What's the big evolutionary jump?

Christopher: The big jump is what you could call the brain's great decoupling. Early organisms, like that Paramecium or even a simple fish like a lamprey, have their perception and action tightly coupled. Mitchell gives the example of the lamprey's escape response. A shadow passes over its eye, and a direct neural pathway triggers the muscles on the opposite side of its body to contract, making it instantly swerve away. See shadow, swerve. It's an almost instantaneous, hardwired reflex. Lucas: It's like a non-player character, an NPC, in a video game. It has a simple "if-then" script. If player is near, say hello. If player attacks, run away. There's no deliberation. Christopher: That's a perfect analogy. Now, contrast that with what happened in the evolution of mammals, and especially primates. The development of the massive neocortex, particularly the prefrontal cortex, acted like a revolutionary software update. It inserted a gap—a pause—between perception and action. Lucas: The pause button! Christopher: Exactly! You see a donut on the table. The lamprey’s equivalent would be to just eat it. The perception of food would be directly coupled to the action of eating. But your human brain doesn't do that. The perception—"donut"—is broadcast to this vast network in your cortex. And in that pause, your brain does something incredible: it starts running simulations. Lucas: That's the internal monologue! "Ooh, a donut. It looks delicious. I'll get a sugar rush. But I'm on a diet. I'll feel guilty in an hour. My long-term goal is to be healthy. Maybe I should have an apple instead." Christopher: You're literally simulating possible futures and evaluating them based on your internal state, your memories, and your goals. The prefrontal cortex is the hub for this. It allows you to hold information in working memory ("there is a donut"), retrieve relevant knowledge ("donuts are high in sugar," "I have a goal to be fit"), and inhibit your immediate, reflexive impulse to just grab it. You've decoupled the stimulus from the response. Lucas: It’s like when I'm playing a complex strategy game. I don't just move my pieces randomly. I pause, look at the whole board, consider my opponent's possible moves, and think three steps ahead before I commit. The lamprey is stuck playing checkers on auto-play; we get to play chess. Christopher: And that capacity for simulation is the foundation for a much higher form of agency. We are not just acting on the world as it is; we are acting on our models of the world and our projections of its future. We can make choices based on things that haven't happened yet, or things that might never happen. That's a profound level of freedom. Lucas: This all makes perfect sense, but it leads me right to the killer question, the one the skeptics always raise. If my choices are the result of these simulations, which are based on my brain's wiring, my memories, my goals—all things shaped by my genes and my past experiences—am I truly free? Or am I just a very, very sophisticated puppet, whose strings are my own biology and history?

Christopher: That is the central paradox, and it’s where Mitchell makes his most powerful, and perhaps most controversial, argument. He says the skeptics who call us puppets are using a definition of "free will" that is incoherent to begin with. Lucas: What do you mean, incoherent? The idea is simple: could I have chosen otherwise? If you rewound the tape of the universe to the moment I saw the donut, could I have made a different choice? The determinist says no. Christopher: And Mitchell says that's the wrong way to frame it. He quotes the philosopher Daniel Dennett, saying, "You can have 'free' or you can have 'we,' but you can't have both." Lucas: Okay, you're going to have to unpack that one for me. Christopher: The absolutist definition of freedom is freedom from all prior causes. To be truly, absolutely free, your choice would have to be unconstrained by your memories, your personality, your values, your goals. But what is that "you" that's left over? If you strip away all those things, you strip away the self. There's no "we" left to do the choosing. You'd just be a random action generator. Lucas: Wow. Okay. So the very things that skeptics point to as constraints—my character, my desires, my history—are not the opposite of my freedom. They are the very substance of the self that is exercising the freedom. Christopher: Precisely. Freedom isn't being free from your character; it's the freedom to act in accordance with your character. The choice is yours because it is generated by the unique, integrated system that is you. You are not a puppet whose strings are being pulled by your brain. You are your brain, your body, your history, all acting as a unified whole. Lucas: So when people bring up those famous neuroscience experiments, like the Libet experiment, where brain activity seems to show a decision is made before the person is consciously aware of it... what's Mitchell's take on that? Christopher: He argues those experiments are largely irrelevant to the real question of free will. In the Libet study, people were told to flick their wrist whenever the "whim" took them. They weren't making a reasoned, meaningful choice. They were waiting for a random neural fluctuation to cross a threshold. Mitchell argues that for arbitrary, inconsequential decisions, the brain is smart enough to use a bit of randomness to just get the job done. But when you ask people to make a deliberative, consequential choice—like which charity to donate money to—that "readiness potential" signal disappears. Lucas: So the experiments that supposedly "disprove" free will were only studying the one kind of choice where free will isn't even relevant: a meaningless whim. Christopher: That's the argument. The real work of agency happens when we use that "pause button"—our prefrontal cortex—to reason about our reasons, to simulate futures, and to make a choice that aligns with our goals and values. That is a real, physical, biological process. It's not magic. It's the pinnacle of a four-billion-year evolutionary journey. Lucas: That's a powerful shift in perspective. The argument that 'my brain made me do it' is missing the point. The constraints aren't my enemy; they're the architecture of my identity. Freedom isn't breaking the strings; it's being the one who gets to pull them.

Christopher: Exactly. And that's the ultimate takeaway from Free Agents. Kevin Mitchell reframes the entire debate. Agency isn't some ghost haunting our biological machine. It is the machine—a machine four billion years in the making, designed for a purpose: to persist, to choose, to act. We, as humans, are simply the most complex, self-aware, and powerful expression of that evolved capacity. Lucas: It makes the whole idea of choice feel so much more profound. It's not just a philosophical abstraction; it's the defining activity of life itself, from the smallest bacterium to the largest brain. It's grounded and real. Christopher: It is. And it leaves us with a really powerful question to reflect on. Lucas: What's that? Christopher: Well, if our freedom comes from our ability to act for our own reasons, it puts the responsibility back on us to know what those reasons are. To use that incredible metacognitive machinery we have to think about our thinking. Lucas: So the next time you make a choice, from what coffee you order to what career you pursue, maybe the question to ask is: what part of your 4-billion-year history is speaking right now? What reasons are truly yours? That’s a powerful thought. Christopher: It really is. We'd love to hear what our listeners think. Does this evolutionary perspective change how you see your own choices? Find us on our socials and let's continue the conversation. Lucas: It's a conversation worth having. Christopher: This is Aibrary, signing off.