We all assume that human perceptual and conceptual apparatuses are sufficient to a large understanding of the world in which we find ourselves. The only people who deny this are radical skeptics—and they can only deny it, as it were, in the lecture hall—and the insane. But, this is a matter of faith. At the very least it is a matter of faith for the vast, vast majority of us who never reflect on just how unlikely this should be.
It is undeniable that our minds allow us to function very well in the world, but other animals have quite different perceptual abilities (bats, dolphins, dogs, just to name three easy examples) and may lack much of anything that we would countenance as a conceptual scheme. And, they get along quite well in the world, too. That is, they get by without having minds that model the world correctly, by our lights. What reason do we have, then, to think that our abilities are the ones that are able to hit upon the truth?
If we are theists—as, for instance, Alvin Plantinga is fond of saying—we can ground our minds in the God who gave them to us. We then do have the problem that this God gave us minds that find as much evidence against the existence of a personal God as they do for it.
But, if we aren't theists or are wary of supporting claims by pointing to God's role, we have an apparent problem, for—again channeling Plantinga—natural selection selects for survival aptitude, not veracity. The most useful conceptual apparatus need not be the one that gets at the world correctly. In fact, it might often be survival apt to get the world wrong, to impute agency where there is none in order better to avoid predators when they are present, for example. Whatever forces act in addition to selection are at play in evolution—and I am no selectionist—do we have reason to believe that they would pressure the mind to match the world? And, do we have much strong reason to think that minds such as ours, which appear to have gone well beyond our mere survival needs, have reached truths when they have gone beyond? We shouldn't forget that humans have invented some pretty amazing—and false—ontologies in their short time on earth.
If true, it is an amazing thing that when consciousness arises it is able to become conscious of the universe in which it has arisen. And, we cannot help but believe that it is so able. But it is worthwhile now and again to reflect on just what a leap of faith this belief is for most of us.