Imagine living in a world where you're the only human and there are no reflective surfaces.
How would you know you had a head? You would see through your eyes, breath and eat with your mouth, touch your hair and face, etc. But you would have no "proof" your head existed because while you had constant direct experience of your head performing its functions, you would have no 3rd party objective confirmation that you had a head at all.
How does the knower know itself outside of its experience?
@Tfmonkey
This is like the gay cousin of the "I think therefore I am" formulation. You'd never have an OBJECTIVE confirmation because how do you know the 3rd party is even real? Look, it's like Daredevil. You close your eyes, then touch your head all over and create a mental image of what shape you are. Simple as. You yourself ARE the objective arbiter, because your experiences are proof enough for your purposes.
Cont...
@Tfmonkey And if this is leading to some "how do you know your experiences are even real or that you're not in the matrix" then my response is simple: I have absolutely no reason to assume the current reality is not reality. Therefore, I won't even consider hypothetical alternatives as they are nothing but unfalsifiable wastes of time. There's no reason to not proceed with the assumption that my current experiences represent reality, therefore I won't deviate.
@ButtWorldsMan the purpose of a thought experiment isn't a puzzle you "solve", it's there to put you into a mental state of mind to think of something in a different way.
BTW, you're describing the principle of Incorrigibility: https://en.wikipedia.org/wiki/Incorrigibility
@Tfmonkey It's still lamer than cogito ergo sum
@ButtWorldsMan The thought experiment is about "the self", which you cannot see, but which you experience in every moment.
Try to come up with a better thought experiment.
@Tfmonkey Thinking occurs, therefore entity capable of it exists.
@Tfmonkey This is all well and good for incessant bickering over thinking and word games about thinking and whose thinking is the thinkiest thinking, but all I care about with regard to philosophy is pragmatic "thinking." Is this world real? I have no reason to assume otherwise, so I'll "assume" it is. Am i, as a thinker, an individual or a hive mind? I don't care. It's a waste of time to consider anything other than I as an individual because my whole life is I. Therefore I am.
@ButtWorldsMan except, no. You cannot know "you are" simply because thinking is occurring.
Who is thinking? How do you know "you" are a singular "I" or not?
The saying "I think therefore I am" makes a lot of unquestioned assumptions.
I'm not the first one to point this out. Nietzsche did as well: https://qr.ae/py97b7
TL;DR "Without our authorization or permission, the thinking happens, after which we latch onto it and claim it as our own."