“This view starts from the fact that we have made our starting point in this chapter,-namely, that only consciousness is immediately given. All the objects that we know are objects of real or possible experience. Now, a chair or table as we experience it must confirm to the laws of our mind, for nothing could be experienced by a mind if it did not conform to the laws by which a mind can have experience. As we ahave seen, a mind cannot regard anything as true which is not self-consistent. Kant showed further that the mind treats as real only that system of objects which obeys the laws of the “forms of sensibility” (space and time) and the “categories of the understanding” (substance, causality, etc.). Hence, Kant argues, scientific knowledge is possible and skepticism is refuted, for the laws of space, time and causality must necessarily be true of every object that the mind recognizes as real. Kant holds that the “content” of knowledge comes from sensation, but insists that its “form” (the universal, or law-element) comes from understanding…Sense intuition gives the data, but the understanding organizes the data, gives them form and law, and thus makes knowledge possible.
Knowledge, then, is possible; but knowledge of what? Knowledge only of phenomena, of things as they appear to us, in our minds; with laws that come from our minds rather than from things! Things-in-themselves we can never know; they are forever inaccessible to us. The knowability of things as they appear has as its reverse side the unknowability of things as they are…we know only the content of experience and its laws; or phenomenalism, for it holds knowledge to be confined to phenomena,-things as they appear to us. As far as things-in-themselves are concerned, this theory of knowledge surrenders to skepticism…”
(Brightman, Introduction to Philosophy, 74)