ABSTRACT
This is a variant of a paradox found in the fourteenth century writings of Albert of Saxony and of a medieval logician called Pseudo-Scotus, so called because at first his writings were wrongly attributed to John Duns Scotus. (It was the genuine Duns Scotus whose name gave rise to our term ‘dunce’: during the Renaissance there was a reaction against what was regarded unfairly as the hair-splitting of such medieval logicians.)
One way of dealing with this paradox exactly parallels the third approach mentioned in the discussion of The Liar. Any argument that includes among its premisses or conclusion a claim about its own validity or invalidity is defective, for the sentence trying to express that claim fails to express any statement. The constituent sentences, construed as referring to the argument in which they occur, fail to express any statement, true or false.
