People possess the unique ability, only ever found within humans, to explain reality and make objective progress. This applies to all domains of knowledge. A progress creating, truth seeking culture will advance all domains. The knowledge people create is real and autonomous—not at all about us, but about reality.
A simple test can be applied to test whether or not knowledge is autonomous: kicking. Kick a rock and it kicks back, kick the number 2 and it kicks back. Abstract concepts, when kicked (by means of conjecture) recoil against criticism. The number 2 is abstract and also real. Here's a heuristic: what is real is that which once seen, cannot be unseen. Objective knowledge has a uni-directional property.
A common misconception is that in some domains, objective progress cannot be made. Domains like art and morality are among those generally considered to be subjective—differing in value between individuals. Subjectivity is in my opinion vastly overblown, and it still does not detract from a problem's objective solubility. Artists spend countless hours honing their craft, if they aren't making objective progress then what are they doing? They have a problem, whether they're aware of it or not, to which they can envision a perfect solution to which they are aspiring to.
Post-modernist art sucks for this very reason. The feeling post-modern art seeks to evoke is dependent on the observer's pre-existing expectations. Ultimately, what is challenged is the most traditional expectation of art, that art ought to be beautiful. Behind the veil of subjectivity, post-modernists intellectualize themselves to be above beauty itself. Post-modernists understand what beauty is, because it is what they are subverting, but instead of aspiring to it, they do the far less difficult thing: give up and feign "subjectivity" or worse "de-construction". Beauty is objective, it's really there, because if it weren't post-modernists would have nothing to subvert!
Morality too faces much of the same misconceptions as the arts do, but the consequences are far more grave. Objective moral progress can be made, and has been made, particularly in what we call today "The West".
There can never be an "absolute source of truth", people are fallible and ever error-correcting. This leads many to think that morality cannot be objective, but that is wrong. People don't need an "absolute source of truth" to make progress towards the truth. Within the West, the concept of human rights is universally accepted. Conversely, slavery and domestic abuse have become universally rejected, despite being common until only relatively recently. Most moral problems are specific, which is why we have established systems of justice to judge cases. It might be that some problems (such as: "Is divorce good?") have no universal answer, but that is same for science and all other domains of knowledge too. It takes creativity to unify theories that solve specific problems. Through conjecture, Western culture has created the most moral culture in history. Thus, the values that a culture needs to allow progress must allow for error-correction, such as: freedom of speech and non-violent conflict resolution.
If morality is objective, what logically follows is that some cultures, on Earth today, are objectively more moral than others. A simple heuristic as to which cultures are better than others is to note: where are people emigrating to? It is no coincidence that countries with the best quality-of-living, attracting immigrants, should have a specific culture—namely, a culture of making progress. It is precisely this culture which has created the quality-of-living. In other words, the culture ascribed to what we today call "The West" is a pre-requisite for creating Western quality-of-living. A problem that faces the people of Western culture in particular is that only a culture with the values of open dialogue and self-reflection will cause it's people to ask themselves: "Are we the good guys?". Cultures without such values will never second guess themselves, and cannot co-exist with truth-seeking, error-correcting cultures.
If morality or the arts are just purely random guessing, we should expect the world to be a lot uglier and more evil because random guesses are more likely to be wrong than they are to be right. Progress will never occur spontaneously, it will be through deliberate, concentrated effort. We can start that effort by at least acknowledging that making progress towards good and beauty is what we want. Good and beauty are real; strive for them or guarantee their inverse.