Human beings have repeatedly demonstrated that we can construct explanations that are coherent, persuasive, and apparently comprehensive while remaining mistaken about fundamental aspects of reality. Throughout history, ideas once regarded as compelling explanations of the universe - like the idea that planets moved in 'perfect' circles - have been revised or abandoned as our knowledge has advanced. This history should give us reason to question not only the conclusions we draw, but also the confidence with which we draw them. Our understanding of the universe is necessarily limited, not merely by what we have yet to discover, but potentially by limitations in our own cognitive abilities and conceptual frameworks. We cannot even be certain that we can identify all the limits of our knowledge, because our ability to determine the limits of our knowledge is itself constrained by the very knowledge and cognitive abilities whose limits we are trying to determine. There may be possi...