Let We Tell You What I think

AITOOW wonders what the hell is going on in your brain when you have an "argument" with yourself? Don't the kind that starts with it processing an "external/foreign" idea. The times when you literally disagree with your mind. Sometimes it is referred to as "conscience". Sometimes it is just "thinking out loud". I guess Freud would explain the conscience "arguments as an ego/super ego and id issue. But, that is more philosophy than science. What does science/biology say? Is it separate "filing cabinets" of personality collected in neurons and they vie to be put on speed dial? Is repetition the "manure" that helps the beliefs that form "us" develop? Do we produce/anticipate "external" opinion after enough exposure to it? Is that the "other voice"?