Lucretius and the Epicurean View that "All Perceptions are True"

The well-known and controversial thesis that “all perceptions are true”
is endorsed by all Epicureans. At least three general interpretations of it have
been provided by commentators and interpreters, based on respective meanings
assigned to the predicate “true” (‘propositional’, ‘existential’, ‘factive’ meaning)
as well as on the alleged objects/contents perception is thought to be of (eidola/
proximal stimula or environmental objects/distal stimula?). Starting from this
puzzle, this paper will address the more general issues involved in the Epicurean
theory of visual perception (theory of eidola/simulacra) and interpret the epistemological
meaning of the ‘controversial thesis’ in the light of Lucretius’ treatment
of vision, illusion and dreaming in DRN Book 4. It will turn out that Lucretius has
a very sophisticated view on perceptual epistemology.