The concepts themselves are the ground of knowledge. Each concepts is necessarily expressed so grounding there is something for us to know.
The world has necessarily expressions of conceptual meaning, such that things, be they empirical truths (they express a concept which allows understanding of them) or logical ones. Human experience adds nothing special to them. Our experiences are just moments when we understand some of this necessary conceptual order.
Issues understanding the place of knowledge do stem from moves made by the empiricists, in the sense of philosophers, such as Kant, who equate our experience as the grounding of our knowledge. In claiming our experience is the origin of knowledge, they undercut the underlying conceptual order. We get stuck in a position of being unable to say necessary concepts define knowledge because what is known get reduced to a function of contingent experience. We mistake means of our knowing (our experiences) for the means of what is known (whatever truth we might know or not).
To unpick this equivocation, we have to return to the question of how there are things to know. What is it we need to know about something? How do our experiences of knowledge have understanding?
Once we make the move back to an account of Rationalism, where a necessary conceptual order forms the things we know, something interesting happens in the context of empirical knowledge. Since events of the world are of the necessary conceptual order, rather than just our experiences,
empirical observation is not the foundation of knowledge , including of
empirical states.
We can know about empirical events
we never even observe.
In the context of metaphysics this very important because it reveals an incoherence to certain empiricist objections to
realism. If I want to make a claim about the past world I never observe, we find I am no longer attempting the impossible.
Since the necessary conceptual order grounds the meaning of events, I just need the right concept to understand a state present before I exist and observe. I can know, for example, it was true dinosaurs roamed the Earth perfectly well. I just need the concepts expressed by those past living beings