Supposition theory was a branch of
medieval logic that was probably aimed at giving accounts of issues similar to modern accounts of
reference,
plurality,
tense, and
modality, within an
Aristotelian context. Philosophers such as
John Buridan,
William of Ockham,
William of Sherwood,
Walter Burley, and
Peter of Spain were its principal developers. By the 14th century it seems to have drifted into at least two fairly distinct theories, the theory of "supposition proper" which included an "
ampliation" and is much like a theory of reference, and the theory of "modes of supposition" whose intended function is not clear.