On-Line Philosophy Journal. Our belief cannot be justified deductively, the argument continues, because there is an unbridgeable logical gap between the conclusion we wish to arrive at and the only sound premises from which we can set out. If we are to remain strictly within the empiricist scheme of things, we must set out from propositions that refer exclusively to the content of our experience. And, since the conclusion of any valid deduction can contain no reference to any terms which do not already appear in its premises, there is no valid logical path from propositions which refer to our experiential states to propositions which refer to anything that may be imagined to transcend those experiential states. Again, it cannot carry us across the logical divide between propositions which refer exclusively to the content of our experience and propositions which include reference to any entities supposedly transcending that experience.
Realists respond to the sceptical argument by denying that there is any logical gap to be bridged.
The propositions that comprise the premises from which we infer the existence of an independent external reality, they insist, refer not to our experiential states but to the actual physical objects that 'give rise' to those states. The difficulties involved in finding a rational warrant for this assertion, however, have been rehearsed at length by its empiricist critics. The superstition that our experiential states are in some sense 'caused' by physical objects, for example, was unmasked as long ago as the 18th century by such thinkers as Berkeley and Hume. The humanist response to the sceptical argument, on the other hand, is far more compelling. Instead of seeking to either bridge or deny the logical gap, it simply presses empiricism to its most radical conclusion and accepts that, in the last analysis, we simply cannot step out of our experience of the world to see what the world might 'really' look like.