[The mind is] full of claims and reasons. "You're a little depressed because of all the stress at work," it says. (It never says, "You're a little depressed because your serotonin level has dropped.")
Sometimes its interpretations are not credible, as when you cut your finger and it starts yelling, "You're gonna die!" Sometimes its claims are unlikely, as when it says, "Twenty-five chocolate chip cookies would be the perfect dinner."
Often, then, it doesn't know what it's talking about. And when you decide it's wrong, who or what is making that decision? A second, superior interpreter?
Why stop at two? That's the problem with this model. It's endless. Each interpreter needs a boss to report to.
The point is, the brain talks to itself, and by talking to itself changes its perceptions. To make a new version of the not-entirely-false model, imagine the first interpreter as a foreign correspondent, reporting from the world. The world in this case means everything out or inside our bodies, including serotonin levels in the brain. The second interpreter is a news analyst, who writes op-ed pieces. They read each other's work. One needs data, the other needs an overview, they influence each other. They get dialogues going.