Referenced from Sedley - Epicurean Theories of Knowledge from Hermarchus to Lucretius And Philodemus - regarding Cicero's Lucullus 80)
A further attempted innovation likely to have been motivated by the challenge of Academic scepticism is attributable to the Rhodian Epicurean Timasagoras. We have already encountered one of his two recorded innovations to the school’s doctrine of vision. The other, noted by Cicero (Lucullus, 80) in his defence of the New Academy’s scepticism, concerns the case of seeing double. To judge from the Ciceronian context, the debate ran more or less as follows.
1) Epicurus insists on the truth of all sense-perceptions. If a single case of a false sense-perception were found, trust in the senses would collapse. But in fact the eye simply registers with unfailing accuracy the visual data reaching it. In all alleged cases of optical illusion the errorlies in the mind’s misinterpretation or over-interpretation of those visual data.
2) Critics from the New Academy respond with the counterexample of an eye squeezed out of shape and as a result falsely seeing the single flame in a lamp as two flames. Here what appear to the eye are the visual data, but not in the form in which they first reached it.How can the Epicureans say that the appearance is ‘true’, when it is not even true to those visual data?
3) Timasagoras replies on behalf of the Epicureans that never, when he has squeezed his eye while looking at a lamp, have there appeared to him to be twoflames. This supports the Epicurean thesis that falsehood is always located in the added opinion, not in the eyes themselves.
In stage (3), does Timasagoras mean (a) that in the situation described the bare visual appearance has never even momentarily lookedto him like two flames? Or (b) that he has never been misled into thinkingthat there actually were two flames? Cicero seems to understand the latter. But on either understanding Timasagoras’ reply would be meant to disqualify the Academic example fromcounting as a genuine optical illusion at all, and thereby to block it from being used as the single counterexample that Epicurus in stage (1) conceded would suffice to destroy his most fundamental epistemological doctrine.
