What would be complete thinking?

 [Sonnet 5 ] 

Complete thinking is the full circuit — not one half standing in for the other. There are really two moves, and both have to actually happen:

1. Generate a real position — one specific and exposed enough that it could turn out to be wrong. (The "ask a hard question, then wait for the answer" part from before is how you make this move honestly, instead of just grabbing the first comfortable thought that shows up.)
2. Expose it to opposition with genuine force — something actually capable of beating it, not a strawman you've quietly arranged to win against.

"Listening is half of thinking" named move 2 specifically for the conversational version of this circuit, where another person supplies the opposition. But the circuit itself doesn't care whether it runs inside one skull or across two people — what matters is whether both moves are real.

Which is why both versions have their own way of faking it. Solitary: you "divide yourself into three people" and stage the debate, but if you already know, going in, which inner voice is going to win, you haven't run a cross-examination — you've performed one with the verdict pre-loaded. That's rumination with better production values, not thought. Social: you go find someone with a different opinion, which looks from the outside exactly like thinking-by-talking — but if you're just waiting for your turn to rebut rather than letting their point actually land, you've done the speaking half and skipped the listening half. You're back to muddleheaded, just with company.

So the real test is the same in both cases: could this position actually have lost? Popper built a whole method for science out of that one question — a hypothesis only counts as such if you're genuinely trying to falsify it, not just collecting confirmations. Devil's-advocate practice in group decision-making is the institutional version of the same move, done on purpose precisely because people don't reliably do it to themselves.

One more route worth naming: writing. Putting a thought into full sentences and then rereading it does both moves at once — it forces the honest generation step, and rereading meets your own idea from something closer to an outside vantage point than simply having thought it ever gets you. It's a way of listening to yourself.