What is the reality I perceive?
I gave you a hint already, I say "I perceive". I go with Descartes here.
"cogito, ergo sum,"
"I think, therefore I am"
At a minimum, I am something and I want to know further what that is. I seem to perceive things, but I am told there are others who cannot assume to have certain senses. On top of that, I am not tetrachromatic so I know I already "cannot see" some colors. Some animals use echolocation, or have the ability to visualize infrared, or can sense EM waves as a geolocator. At any rate, my "am"ness is bound by some set of perceptions. All of these statements about animals are themselves bound by the abilities of perception available to a human. Can we be certain a dog sees no color?
It feels like a "brain in a vat" problem to consider this for too long, so instead I work to assume I "can" perceive reality through my senses in a sensible way. I recognize the senses and perception to be both limited and corruptible, so parity must be gained via introspection, thinking, and communication with other perceiving beings.
There is a problem with what I have said above though. It is arbitrary to trust these senses, and to trust the perceptions they give me. I have no reason to trust them, and I have no reason to trust the perceptions of others. No matter how much I say, "Well, being a brain in a vat would be inconsequential, it actually is entirely consistent with my experience, and I can still have a meaningful life as a brain in a vat, so I have no reason to worry about it." I have no reason to trust that, and it is intense copium.
