Ok, now prove this is true. Can you do so without invoking unobservable properties? If you can, then observable is all that matters, if you cannot then you have no proof.
How can you reliably deny the presence of an experience of another if you cannot prove that experience in yourself?
With the duplicate mother problem, if you cannot tell then there is no reason to believe that it is not a being of equivalent nature. That is not the same as identity, for a layman approach to that viewpoint, see Star Trek: TNG, Season 6, Episode 24. A duplicate Will Riker is created but is still a distinct entity (and one might argue, more original since has been transported one fewer times). Acting the same as is not the same as being the same entity. Nevertheless it has no bearing on whether the duplicate is a valid entity in its own right.
You feel like I'm not living in the real world, but I am the one asking what basis we have for knowing things. You are relying on the presumption that the world reflects what you believe it to be. Epistemology is all about idetifying exactly how much we know about the world.
It follows from that that you cannot exclude something that appears to have a property if you cannot prove it doesn't or even prove it if it does.
> Most animals are goal-directed, intentional, sensory-motor agents who grow interior representations of their environments during their lifetime which enables them to successfully navigate their environments. They are responsive to reasons their environments affords for action, because they can reason from their desires and beliefs towards actions.
In addition, animals like people, have complex representational abilities where we can reify the sensory-motor “concepts” which we develop as “abstract concepts” and give them symbolic representations which can then be communicated. We communicate because we have the capacity to form such representations, translate them symbolically, and use those symbols “on the right occasions” when we have the relevant mental states.
(Discrete mathematicians seem to have imparted a magical property to these symbols that *in them* is everything… no, when I use words its to represent my interior states… the words are symptoms, their patterns are coincidental and useful, but not where anything important lies).
In other words, we say “I like ice-cream” because: we are able to like things (desire, preference), we have tasted ice-cream, we have reflected on our preferences (via a capacity for self-modelling and self-directed emotional awareness), and so on. And when we say, “I like ice-cream” it’s *because* all of those things come together in radically complex ways to actually put us in a position to speak truthfully about ourselves. We really do like ice-cream.