Do you know what your next thought will be? If so, how? Did you think it before you thought it?

Thinking

It's not that, but it's related to that. It is done in the same manner, with you imagining what the other person would say.

Have you heard of the "rubber duck" method of debugging? The idea is that you put a little rubber duck on your desk and whenever you get stumped by a problem, you explain the problem to the duck and, as you put the problem into words, your brain figures out the answer.

Well it turns out that it works for many tricky problems besides programming, you don't really need the duck, you don't actually have to use your mouth, and you can do it entirely in your own head, having the exchange with an imagined "reasonable person" (who is just another aspect of yourself consciously playing the role.) The key insight is that language is a tool for thinking, expressing problems in language can help your brain reason them out. Once you realize this, you should be able to consciously choose to have conversations with yourself as a tool for figuring problems out.

> That seems crazy to me, because who does the other voice belong to?

Me, obviously. The process is that of authoring a dialogue. If you write a short fictional story about you explaining your problems to a wise sage who asks lots of questions and then tries to come up with a reasonable answer, who is the sage? It's your creation as an author. Now do this process without the pen, just in your head. Who is the sage? The sage is still your creation, it's still an aspect of you, slightly divorced from your ego because you're deliberately playing a roll when you imagine what such a sage would say about your situation. But it's obviously still you, it's not a foreign voice in your head disconnected from your conscious will. It's not schizophrenia, it's just a process of 'talking' problems out to figure them out.

https://en.wikipedia.org/wiki/Rubber_duck_debugging

No, we aren't. Now its true that (well, for me at least) the inner monologue is the exact same experience as when reading text or when planning hypothetical conversations. Or when thinking ahead of words to write. The difference is that it is not planning a hypothetical conversation or something to write, and there is no text being read, and it happens pretty much all the time, except when I'm doing one of those other things (and sometimes as an intrusive interruptions when I am.) If you imagine there exists a common piece of mental infrastructure that is used for each of those actions, its as if it was always on doing a narration except when you are specifically, actively concentrating on using it for some other purpose.

> Hearing voices is schizophrenia.

No, hearing voices that aren't there is an auditory hallucination. Among the things it can be a symptom of is schizophrenia, but "X can be a symptom of Y" is not the same thing as "X is Y".

But an inner monologue is not an auditory hallucination. Its obviously and distinctly internal, not something that "sounds" like it is coming from outside.

> You might classify talking to yourself as a monologue

Because it literally is.

> but when most people discuss this topic, it sounds like they're describing a dialogue (i.e. one between multiple people). That seems crazy to me, because who does the other voice belong to?

I think a lot of people do what amounts to roleplaying out conversations, particular on decisions which are troublesome, with themselves; because this is similar to planning a hypothetic conversation with another person, which I gather people without inner monologues can do without outward speech, I'm not sure how connected it is to an inner monologue. From the perspective of someone with one, its a fairly easy deliberate "mode switch" where you basically decided that that is what the monologue is going to focus on.

It's also conceivable that, within plural systems, there is what amounts to an "inner dialogue" or "inner multiparty conversation". Not being a plural system, I can't comment on that and the degree to which it is perceptually different than an inner monologue.

> If you have an inner monologue, then by definition you should be able to predict what it's going to say - because mono- means just you.

That...doesn't follow. But if you have an experience of a conscious thought of what you are about just instantaneously before you say it, an inner monologue is a lot like that, but without the follow-through of speech. That is, I think you are not only wrong that it is true "by definition" that you should be able to predict an inner monologue, and that this is a false analogy to external speech, but that an inner monologue is perceptually similar to, and may well be fundamentally resusing the same infrastructure as, the natural internal "prediction" (or planning; not sure those things are, in this case, different) of outward-directed speech.

It’d be a really interesting project to measure and classify people’s individual thinking mechanisms. That daemon that seems to exist at the boundary of the conscious and unconscious.

Then again, maybe we wouldn’t want that as yet another data point to be bought and sold.