Source: WWW source unknown
Theories of Knowledge
Prelingually deaf people ironically give great insight to the nature of human thought as it depends on language. Oliver Sacks, in his book review article 'Mysteries of the Deaf'(1), outlines the history of the deaf and sign language, which turns out to be a poignant story of how misunderstood the deaf, especially the prelingually deaf, were centuries before and are still today. Before sign language was formally developed, the profoundly deaf were hopelessly doomed to a life without thoughts, because language is the vehicle for thought. This give much evidence for any epistemology which purports that language is logically prior to thought.
In the article, Sacks quotes the Abbé Sicard, the man who had sign language officially recognized in France, and who revolutionized the way people thought about deaf people. The Abbé Sicard asks,
Why is the uneducated deaf person isolated in nature and unable to communicate with other men? Why is he reduced to this state of imbecility? Does he not get sensory impressions from objects as we do? Are these not, as with us, the occasion of the mind's sensations and its acquired ideas? Why then does the deaf person remain stupid while we become intelligent?The answer to a question of why is always answered within the question, only sometimes the answer needs explaining. In the case of the above question, the answer is, Because they are deaf, because they do not have language. The answer is too obvious to see by some who are Foundationalist, or who believe that speech (or sign) logically follows thought. That is not the case, if we accept on authority what some of those who lived a significant portion of their lives deaf and without language. Pierre Desloges gives an account of his life and what went on in his mind before he learned Sign. Sacks concludes from Desloges' writing, that he could not "entertain `ideas,'... until he acquired sign language."
Some philosophers believe that speech follows thought. In the development of a human, the human observes the world, has thoughts about it, and after being around its parents or other humans who speak, the infant learns that there are sounds or signs which represent individual thoughts in its head, according to such a philosophy of language. After learning enough of the symbols, the infant can communicate those thoughts with other people. Given time, the words follow the syntax of the language, which is only a matter of formal structure. For other philosophers, language is much more, and much different. According to them, the infant has no thoughts until it learns the language. Until then, it merely exists, and has sensory perceptions. As it learns of some rudimentary language skills, it begins to have thoughts in terms of the bits of language that it knows. The individual words do not have meaning out of the context in which they are used, but only in some holistic context. The study of the prelingually deaf gives evidence to the latter theory of thought and language, called the "expressive" view of language(2).
Though the profoundly deaf were once considered incompetent sub-humans, now
they are better understood. Unfortunately, people have been trying to force
them to read lips and speak, which has been nothing but failure, but that is
slowly turning around. The natural language for the deaf is Sign, not anything
like any spoken language. Though the cost was very high and at the expense of
the helpless and misfortunate profoundly deaf, we did get some
understanding of human thought from when the prelingually deaf were
misunderstood and left without communication skills. We learned that without
language, humans can not think.
(1) Sacks, Oliver, (1986), Mysteries of the Deaf,
"New York Review of Books" ,
(March 27), pp.23-33
(2) "American Philosophical Association Newsletter on the Teaching of Philosophy" ,