[[../www-old/solipsism]], yes, but inescapable.
Especially considering that [[every psychological event has a biological correllate]] and [[you can alter that biology in a relatively trivial manner]] to get a different map even though the terrain has not changed.
Unless [[the map is the terrain and the terrain is a projection]]… There is a joke about Merkator projection etc. here, maybe…, and a deeper insight into how models are projections are not 1:1 representations → perception and mental models will always be skewed, twisted and warped.
This may work in our favour. It has so far; we're doing OK as a species, as far as building maps and building complex fantasies on top of those maps.