Modal Illusions or Can We Imagine an Impossibility?
The problem of modal illusions (or the alleged conceivability of the impossibilities) is an essential argument in various controversies over the nature of the possible. The authoress examines several proposals for how to solve the problem. She focuses on the question whether the sense of contradictory descriptions is comprehensible (Can we conceive what is meant by the phrase 'a square circle'?), whether we can speak intelligibly about mutually exclusive mathematical conjectures (Either all prime numbers are sums of two even numbers, or some prime numbers that do not have that property even though we do not know which ones do not, says the Goldbach's hypothesis), and whether we can imagine what contradicts a posteriori natural necessities (Can we visualize a candle that burns with a flame going down or an orange that is not a fruit?). Her main preoccupation is to see if conceivability is a reliable guide in the field of possibilities, and her conclusion is that conceivability cannot be fully trusted in that role.
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