Greg Miller in Science:
In 1688, an Irish polymath named William Molyneux wrote the English philosopher John Locke a letter in which he posed a vexing question: Could a blind person, upon suddenly gaining the ability to see, recognize an object by sight that he'd previously known by feel? The answer has potentially important implications for philosophers and neuroscientists alike. Now, researchers working with a medical charity that provides surgery to restore vision in blind children say they've found the answer to Molyneux's question. It's “no” but with a twist.
Molyneux posed his question in the midst of a philosophical debate about how we comprehend the world around us. An affirmative answer to the question would support the argument that we possess innate (and presumably God-given) concepts that are independent of the senses—for example, that we possess a concept of a sphere, regardless of whether we have only seen one, only felt one, or both. A negative answer to Molyneux's question would support the alternative argument that any concept of a sphere or other object must be tied to sensory experience. In that view, a blind person would have only a tactile concept of a sphere that would be of no use in recognizing the shape by sight.