Recovery of Vision following Blindness

In 1688, William Molyneux sent a letter to John Locke in which he asked whether a man born blind, who had learned to distinguish a globe and a cube by touch, would be able to distinguish them by vision alone, if sight were ever restored. It was not until almost 30 years after the posing of Molyneax's problem that the surgeon William Cheselden reported that a patient whose sight had been restored after years of blindness did indeed have acute difficulties interpreting the visual world. Trying to understand the extent and cause of these [Page 865]difficulties played an important role in the development of 18th-century philosophy as empiricist philosophers, such as Etienne Bonnot de Condillac, Denis Diderot, and Thomas Reid, refined their opinions about the relationship between perceptual concepts and sensory experience, and began to differentiate internal psychological events, such as sensations, perceptions, and cognitive constructs. This entry discusses cases of sight recovery and restored visual abilities.