There is a parable, generally used to explain how limited our subjective experience is, about several blind men feeling an elephant, and coming to different conclusions about its nature; the man who feels its leg concludes it is like a tree, the man who feels its trunk concludes it is like a snake, etc.
What I love about this parable is that it actually has extraordinarily different implications than those who use it intend.
Each man is correct, given his narrow scope of perception - they are each subjectively perceiving very real parts of an objective entity. This is usually acknowledged, and treated as an explanation as to why we shouldn't ignore the perceptions of others; just because they perceive something different than us doesn't mean we're wrong. And this is a valid point.
What IS ignored by those who use this parable, however, is that each blind man is perfectly capable of fact-checking his rivals. Unlike the parable, the real world doesn't have an agent preventing each blind man from walking to the other and checking out his perceptions.
Objective reality, whatever it is, is something we are perceiving with a limited set of faculties. We can't see infrared light, we can't see UV light (unless we've had eye surgery to remove the lens of our eyes, anyways). We can check other people's observations and tests of these things; we can accumulate and assimilate knowledge about objective reality, and come to some very valid conclusions about it.
Give one blind man an hour with the elephant, and he will know it for what it is. Maybe he won't know its color, but color is hardly a meaningful attribute to him. Everything that has meaning and value to him about the elephant can, with time, be learned.
And that's an objective truth.