The nature and history of insolubilia
Medieval literature on ‘insolubles’ began to appear by the early thirteenth century at the latest and continued to the end of the Middle Ages. Insolubles were primarily certain sorts of self-referential sentences, semantic paradoxes like the ‘liar paradox’ (‘What I am now saying is false’). But few authors tried to give a rigorous definition, so that other more or less unrelated kinds of paradoxes were also treated under this heading.
Three periods may be distinguished in the medieval insolubilia literature: (1) from the beginnings to ca. 1320; (2) the period of the most original work, from ca. 1320 to the time of the Black Death (1347–50); (3) after ca. 1350, a period of refinement and elaboration but, with a few exceptions, little that was new.
Resolutions in terms of cassation
Several approaches may be distinguished during the first period. One was called ‘cassation’ – i.e., nullification. On this theory, he who utters an insoluble ‘says nothing’. The earliest known text adopts this view, and by ca. 1225 it was said to be ‘according to the common judgement’. Nevertheless, it soon died out and seems not to have been revived until David Derodon in the seventeenth century. It is not clear how the theory is to be taken. In the middle thirteenth century a text attributed to William of Sherwood discussed several views that might be considered versions of cassation, including one theory that insolubles for semantic reasons fail to be sentences, so the he who utters them ‘says nothing’. This theory has modern parallels, e.g., in Fitch 1970.