All we perceive is subjective. Everything is a matter of perception, perspective, opinion. All we receive from our senses is censored and processed and changed by our brains: previous experience, bias, peer pressure. With all this interference, how can we be sure that what we’re seeing is really there? After all, where I see a monstrosity somebody else sees art. What about sounds? Cows, in my experience, don’t say “moo”, but obviously at some point that’s what somebody has heard and written down. Smells and tastes vary too – I think peanut butter is pretty awful, but someone out there loves it and believes that it tastes wonderful. I think Vegemite is fantastic, but most of the rest of the world would disagree. Touch is an odd one... close your eyes and touch something, you will no doubt identify the object by it’s name or appearance. But what if you touched something you’d never seen? Different people would naturally identify it differently. The most misleading sense is common sense, don’t even get me started on that one.
I conclude that the world only exists by common consensus, and we’re all imagining it as something different. I accept no proof that anything is as it appears or smells or tastes (not that I go around licking windows or anything... much). Nobody is really reading this, because I can’t believe my perception that I’ve just typed it or that any other people exist who could read it if I did.
I might just stop this right here... the logical extension of this concept is that there can be no consequences for actions I’ve only taken in my own perception, and no act I don’t perceive can affect me... that leads to disaster!