What is free will? In Friston’s predictive processing framework, free will isn’t a force that stands outside the brain and overrides it… it’s what the system calls the experience of higher level predictions outcompeting lower-level ones. The brain is a hierarchical prediction machine constantly minimizing surprise, and what feels like a decision is the resolution of competing models, where your prefrontal self model of who you are and what matters generates a stronger attractor than the opposing signal. The sense of “I chose this” is likely a post hoc narrative the DMN constructs after the resolution has already occurred.. agency as story rather than cause. There’s no ghost in the machine, just a very sophisticated model of a self that includes the prediction that it can choose.

Through the vagus nerve and serotonin availability, a dysbiotic gut amplifies lower level threat and conservation signals, making them harder for higher level prefrontal predictions to outcompete. What feels like weakness of will may partly be the system running on a degraded substrate… the DMN then constructs a story about discipline and character over a causal chain that started in the enteric nervous system.

So, you can’t even really perceive some of this. But you essentially can’t overcome it either. The decisions are made before you thought about it.

"It's not my will, it's the will of the bugs in my butt!" yes, very "relieving."

I kid, ;) but I see your point. The idea that you might, say, struggle to resist candy and sweets and it's because some population of your gut biome is fighting for its life if you don't eat sugar... makes sense.

The idea that "I just cut sugar out for six weeks and my willpower to resist sugar went through the roof" ... not because your willpower changed, but because you killed that part of your gut biome.