I float the suggestion that the problem of the external world was originally ontological, not epistemological.
The material world is the great lethal chamber of the soul. Only spiritual heroes can arouse themselves sufficiently to escape from its stupefying effect upon consciousness. (Paul Brunton)
The Brunton quotation is distinctly Emersonian, as witness:
The influence of the senses has in most men overpowered the mind to that degree that the walls of time and space have come to look real and insurmountable; and to speak with levity of these limits is, in the world, the sign of insanity. (Ralph Waldo Emerson, "The Oversoul")
The outer senses are seductive. To seduce is to lead astray. From the Latin infinitive ducere, to lead. Dux, ducis is one who leads, a leader. Hence il Duce who led Italians astray into Fascism. (The latter term is used properly to refer only to the political philosophy of Benito Mussolini.) Here are some other English verbs that derive from ducere: deduce, reduce, induce, educe, educate, abduct, deduct, conduct, induct, etc. and their abstract and concrete nominal forms: abduction, induction, inductance, etc. and abductor, inductor, etc.
But I digress.
The outer senses are seductive. They lead us to posit their objects as ultimately and unquestionably real when they are not. The world of the senses comes to exhaust the cartography of Being. Simone Weil, Platonist that she is, is good on this. As seductive, the outer senses are deceptive: they deceive us into thinking that what is only derivatively real, and thus a mix of the real and the unreal, is ultimately or fully real. The deception concerns not their being, but their mode of being.
Among the philosophical acts whereby philosophy and the philosopher first come to be is by the suspension of our natural world affirmation. This suspension was ancient long before it was modern. The problem of the external world was originally ontological, not epistemological. The question concerned the mode of being of the objects of the outer senses, not "our knowledge of the external world," to borrow a title from Bertrand Russell's eponymous 1929 collection of lectures. The ancient question was not the question: How do we know that there is an external world? but the question: What is the ontological status (illusory, merely apparent but not illusory, fully real) of the external world?
This curious shift from the ontological to the epistemological may be illustrated by the different attitudes toward the paradoxes of Zeno of Elea. What is Zeno arguing? Four possibilities of interpretation:
A. There is no motion. Motion is wholly unreal. Whatever is real is intelligible. (Parmenidean principle: Omne ens qua ens intelligibile est.) Nothing contradictory is intelligible. Motion is unintelligible because contradictory. Ergo, nothing moves. Motion is an illusion.
B. Motion is wholly real, 'as real as it gets.' The apparent contradictions involved in motion are merely apparent. The Zenonian arguments are fallacious and they can be shown to be fallacious. The 'calculus solution.' See Wesley Salmon.
C. Motion is phenomenally real, but not noumenally real. It is neither wholly unreal not wholly real. It is mere appearance. Ultimate reality is motionless , but phenomeal reality is not nothing.
D. Motion is unintelligible but nonetheless real. Mysterian position. The Zenonian arguments cannot be refuted, but motion is nevertheless wholly real. Motion is actual, hence possible, despite the fact that we cannot understand how it is possible.
