In the material world, all observation is conditioned, which means (1) we focus on a certain part of reality instead of the whole reality, so we cannot say that we know the whole truth, (2) we understand the object of knowledge in terms of previously acquired concepts, and (3) we are attracted to a certain part by our innate sense of incompleteness. Now, there are three kinds of approaches you can use to overcome the effect of this experiential conditioning.
First, you can say that the knower must be a ‘blank slate’ — i.e. no preference for anything, no presuppositions about anything, and no specific focus on anything. The problem is that once you become a blank slate you have no preference, no focus, and no presuppositions you can know anything. You can’t say that you know anything without these things. So, this idea that we can know the truth by removing the conditioning and being a ‘blank slate’ fails.
Second, you can say that if that reality reveals itself and says — “this is what I am” — then we can accept it as the presupposition in terms of which we cognize and then we can say we know. However, this raises the question of whether the authority that revealed oneself knew oneself perfectly. The short answer is that every relationship reveals something new. So, you might think that you know yourself as a calm and peaceful person, but something can make you go wildly angry. You don’t know that you had anger in you until you encounter that situation. In that sense, it is almost impossible to say that even the authority revealing himself knows the whole truth. Thus, it is sometimes said that even Krishna doesn’t know what He is in entirety because new things about Himself are revealed to Him through every new kind of relationship interaction.
Third, you can say that the thing we know is actually known differently through many perspectives. What we know is contingent on the relationship and method of knowing and the part we chose to know. Other relationships, methods of knowing, and parts may be different from what we know. So, if we qualify our knowledge by the relationship, method of knowing, and the choice of the part we know, then we can say that we know. But we can’t preclude other ways of knowing, through different kinds of relationships, and different kinds of conscious focus. So the path to overcoming ‘conditioning’ is to check against other perspectives.
Once we realize that all knowledge is subject to perspective, then the question becomes: Whose perspective is better? In general, the perspective that is higher is better, which means if you see the forest, it is better than if you just see the leaves. But once you have seen the forest, then you must also see the leaf. So, one has to keep traversing up and down and find everything. Since it is infinite, nobody can say that we know everything. But that doesn’t mean they are in illusion. They just have knowledge relative to their perspective(s) and they are eager to know how things are from other perspectives. The person who knows is still eager to listen to that same thing again and again. So knowledge doesn’t mean the end of discussion on that knowledge.