David Hume

David Hume delivered a decisive blow to this program of metaphysical realism by demonstrating that there are no grounds in or in sense experience to compel one's adherence to any metaphysical formulations about the world out there. We are never able to get out there to see whether our formulations about the world are adequate or not. The whole idea that one can escape experience in order to validate one's inferences from experience to reality was, Hume thought, misguided. We are imprisoned in a realm of experience, even though what happens "in here" may tempt us to infer certain things to be the case out there -- there 'must' be some permanent substance or enduring forms, or some comic process, or some intelligent deity out there. But despite the strength of our temptations to formulate inferences, nothing can change the fact that they are just that -- mere inferences. And nothing can change the fact that we have no means by which to certify their adequacy, unless, of course, one is prepared to accept the authority of additional inferences. But where do we get ourselves by creating hierarchies of uncertifiable certificates? Certainly we do not get beyond the inferences themselves to some sort of transcendent foundations. So Hume concluded that there were no certain grounds under any proposed philosophical formulations about the way things really are. Indeed, we cannot even know that an extra-experiential world exists out there, let alone have the assurance that our inferences about its essence are adequate. Hume acknowledged that some profound psychological needs may be driving our inferences from experience to reality, but this state of affairs only forces the admission that our formulations say more about the knower than about the known.

Hume appeared to have undermined the entire program of the foundational tradition, leaving no recourse for deciding whether any particular formulation about the world out there was more or less adequate than any other formulation. In the wake of Hume's devastating critique of metaphysics Immanuel Kant attempted to restore the integrity of the foundational tradition. He was stunned by Hume's conclusion that no vocabulary for adequating appearance to reality could be known to be better or worse than any other vocabulary. This conclusion, he saw,would have the effect of relativizing the authority of scientific enterprise. So he set about to achieve a "Copernican revolution" by which he proposed to reorient the foundational tradition of epistemological grounds. ~ Page 270/271