Locke's idea of the mind being a tabula rasa had a significant influence on later approaches to mental retardation. If ideas derive from experience, from the senses and through reflection, then there is hope of developing these capacities in persons with intellectual disabilities. Prior to this time, it was assumed that persons born with any type of mental disability were unable to learn. Of course, not everyone shared Locke's view, but it did play a significant role in the development of psychology.
University studies of this time included those of Jacob Rodriguez Pereire (1715-1780) in Portugal, who instructed "deaf mutes" and taught them to hear and speak by touch and vibration through muscles. Scientists were amazed that students could imitate speech perfectly, even dialects. In the 1780s, Valentin Hauy developed embossed print and claimed that blind persons could be taught to read. These successful efforts to educate persons who were blind and deaf encouraged an interest in educating persons with other disabilities.
Philosopher, writer, and political theorist, Jean Jacques Rousseau (1712-1778) believed that man's perfect nature was spoiled by corrupt society. Rousseau's belief that there is worth and value in all human beings was a revolutionary idea, challenging the nobility who believed in their own superiority. Like John Locke, Rousseau believed in the tabula rasa concept. Rousseau asserted, "Man is born free, but is everywhere in chains."