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SOBRE A DEFICIÊNCIA VISUAL


An Essay Concerning Humane Understanding

John Locke

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The Sense of Sight-Jan Brueghel the Elder, 1618  (com a colaboração de Rubens)
O Sentido da Visão - Jan Brueghel o Velho, 1618

 

No innate Ideas in the Memory.

Suppose a child had the use of his eyes till he knows and distinguishes colours; but then cataracts shut the windows, and he is forty or fifty years perfectly in the dark; and in that time perfectly loses all memory of the ideas of colours he once had. This was the case of a blind man I once talked with, who lost his sight by the small-pox when he was a child, and had no more notion of colours than one born blind. I ask whether any one can say this man had then any ideas of colours in his mind, any more than one born blind? And I think nobody will say that either of them had in his mind any ideas of colours at all. His cataracts are couched, and then he has the ideas (which he remembers not) of colours, DE NOVO, by his restored sight, conveyed to his mind, and that without any consciousness of a former acquaintance. And these now he can revive and call to mind in the dark. In this case all these ideas of colours which, when out of view, can be revived with a consciousness of a former acquaintance, being thus in the memory, are said to be in the mind. The use I make of this is,—that whatever idea, being not actually in view, is in the mind, is there only by being in the memory; and if it be not in the memory, it is not in the mind; and if it be in the memory, it cannot by the memory be brought into actual view without a perception that it comes out of the memory; which is this, that it had been known before, and is now remembered. If therefore there be any innate ideas, they must be in the memory, or else nowhere in the mind; and if they be in the memory, they can be revived without any impression from without; and whenever they are brought into the mind they are remembered, i. e. they bring with them a perception of their not being wholly new to it. This being a constant and distinguishing difference between what is, and what is not in the memory, or in the mind;—that what is not in the memory, whenever it appears there, appears perfectly new and unknown before; and what is in the memory, or in the mind, whenever it is suggested by the memory, appears not to be new, but the mind finds it in itself, and knows it was there before. By this it may be tried whether there be any innate ideas in the mind before impression from sensation or reflection. I would fain meet with the man who, when he came to the use of reason, or at any other time, remembered any of them; and to whom, after he was born, they were never new. If any one will say, there are ideas in the mind that are NOT in the memory, I desire him to explain himself, and make what he says intelligible.


Sensations often changed by the Judgment.

We are further to consider concerning perception, that the ideas we receive by sensation are often, in grown people, altered by the judgment, without our taking notice of it. When we set before our eyes a round globe of any uniform colour, v.g. gold, alabaster, or jet, it is certain that the idea thereby imprinted on our mind is of a flat circle, variously shadowed, with several degrees of light and brightness coming to our eyes. But we having, by use, been accustomed to perceive what kind of appearance convex bodies are wont to make in us; what alterations are made in the reflections of light by the difference of the sensible figures of bodies;—the judgment presently, by an habitual custom, alters the appearances into their causes. So that from that which is truly variety of shadow or colour, collecting the figure, it makes it pass for a mark of figure, and frames to itself the perception of a convex figure and an uniform colour; when the idea we receive from thence is only a plane variously coloured, as is evident in painting. To which purpose I shall here insert a problem of that very ingenious and studious promoter of real knowledge, the learned and worthy Mr. Molineux, which he was pleased to send me in a letter some months since; and it is this:—“Suppose a man BORN blind, and now adult, and taught by his TOUCH to distinguish between a cube and a sphere of the same metal, and nighly of the same bigness, so as to tell, when he felt one and the other, which is the cube, which the sphere. Suppose then the cube and sphere placed on a table, and the blind man be made to see: quaere, whether BY HIS SIGHT, BEFORE HE TOUCHED THEM, he could now distinguish and tell which is the globe, which the cube?” To which the acute and judicious proposer answers, “Not. For, though he has obtained the experience of how a globe, how a cube affects his touch, yet he has not yet obtained the experience, that what affects his touch so or so, must affect his sight so or so; or that a protuberant angle in the cube, that pressed his hand unequally, shall appear to his eye as it does in the cube.”—I agree with this thinking gentleman, whom I am proud to call my friend, in his answer to this problem; and am of opinion that the blind man, at first sight, would not be able with certainty to say which was the globe, which the cube, whilst he only saw them; though he could unerringly name them by his touch, and certainly distinguish them by the difference of their figures felt. This I have set down, and leave with my reader, as an occasion for him to consider how much he may be beholden to experience, improvement, and acquired notions, where he thinks he had not the least use of, or help from them. And the rather, because this observing gentleman further adds, that “having, upon the occasion of my book, proposed this to divers very ingenious men, he hardly ever met with one that at first gave the answer to it which he thinks true, till by hearing his reasons they were convinced.”


This judgement apt to be mistaken for direct perception.

But this is not, I think, usual in any of our ideas, but those received by sight. Because sight, the most comprehensive of all our senses, conveying to our minds the ideas of light and colours, which are peculiar only to that sense; and also the far different ideas of space, figure, and motion, the several varieties whereof change the appearances of its proper object, viz. light and colours; we bring ourselves by use to judge of the one by the other. This, in many cases by a settled habit,—in things whereof we have frequent experience is performed so constantly and so quick, that we take that for the perception of our sensation which is an idea formed by our judgment; so that one, viz. that of sensation, serves only to excite the other, and is scarce taken notice of itself;—as a man who reads or hears with attention and understanding, takes little notice of the characters or sounds, but of the ideas that are excited in him by them.

The End

 

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John Locke (b. 1632, d. 1704) was a British philosopher, Oxford academic and medical researcher. Locke’s monumental 'An Essay Concerning Human Understanding' (1689) is one of the first great defenses of modern empiricism and concerns itself with determining the limits of human understanding in respect to a wide spectrum of topics. It thus tells us in some detail what one can legitimately claim to know and what one cannot. (Stanford Encyclopedia) In 'An Essay Concerning Human Understanding', Locke considered the question of whether a person born blind who became sighted would be able to recognize objects previously known only by touch. Locke asserted that newly sighted people would not be able to understand the world using their new vision. (Britannica)

 

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excerpt of
The Project Gutenberg EBook of
'An Essay Concerning Humane Understanding', Volume I.
by John Locke
MDCXC
https://www.gutenberg.org/files/10615/10615-h/10615-h.htm

   


 

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26.Out.2021
Maria José Alegre