“However, the expression “perception is reality” can be used in another way- one that denies any fixed reality at all. The assumption here is, ‘We each have our own perceptions. You have yours; I have mine. What you perceive is your reality, and what I perceive is mine. What you perceive to be real isn’t necessarily what I perceive to be real. And, my no-fixed-reality applies to everyone.’
In response, we might ask the advocate of the perception-is-reality view: “Is that just your perception, or is your view describing reality?” That is, either his view is trivial, insignificant, and ignorable- his own perception- or he’s speaking about reality for all people (that reality actually and universally is perception).
Another difficulty arises: If everything’s a matter of perception, where did we even get this idea that we can distinguish beween perception and reality? The answer is, we wouldn’t make the distinction unless we’ve connected with a fixed reality that doesn’t depend upon our perceptions. (We do distinguish between dreaming and wakefulness, between drug-induced hallucinations and drug-free lucidity…
Everything we perceive isn’t real. Indeed, the fact that we misperceive reminds us that perception isn’t necessarily capturing reality. “Perception is reality” turns out to be another slogan riddled with problematic assumptions.”
(Copan, True for you but not for me, 57-58)