The Molyneux Problem: a curious thought experiment

In 1688, the Irish scientist and politician William Molyneux sent a letter to the well-known philosopher John Locke in which she raised an unknown that aroused the interest of the entire scientific community of the epoch. Is about a thought experiment known as the Molyneux Problem, and still arouses interest today.

Throughout this article we will talk about this debated and discussed issue both in the field of medicine as well as philosophy and that still today generates numerous disagreements between researchers and thinkers.

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What is the Molyneux Problem?

Throughout his entire career, Molyneux was especially interested in the mysteries of optics and the psychology of sight. The main reason for this is that her own wife lost her sight when she was still very young.

The main question posed by the scientist was whether a person born blind who over time has learned to distinguish and name different objects by touch, he would be able to recognize them with his sight if she at some point in her life got it back.

The antecedents that led Molyneux to formulate this question were inspired by a writing by the philosopher John Locke in which he made a distinction between ideas or concepts that we acquire through a single sense and those for which we need more than one type of perception.

Since Molyneux was a great admirer of this English intellectual, he decided to send him his reflections by post... which, at first, got no response. However, two years later, with the recent friendship between these two thinkers, Locke decided to reply, in addition, with great enthusiasm.

He included the Molyneux Problem within his work, making it possible for said reflection to reach a much wider audience.

Locke exemplified this question as follows: a man blind from birth learns to distinguish by touch a cube and a sphere made of the same materials and with the same size. Suppose now that this man regains his sight and both objects are placed in front of him, could he then distinguish and name them without first touching them, only with his eyes?

The Molyneux Problem at that time attracted the attention of numerous philosophers, most of them converted into references today. Among them were Berkeley, Leibniz, William James and Voltaire himself.

The first discussions of the time

The first reactions of the philosophers of the time denied first of all the possibility that a person blind from birth could acquire sight, so considered the Molyneux Problem as a kind of mental challenge that could only be solved by reason.

All of them agreed that the sensations perceived by the senses of sight and touch differ from each other, but they managed to establish an agreement about how they were related. Some of them, like Berkeley, thought that this relationship was arbitrary and could only be based on experience.

However, some determined that such a relationship was necessary and based on innate knowledge, while others, like Molyneux and Locke themselves, thought that this relationship was necessary and learned through experience.

Having collected the opinions and thoughts of each and every one of these philosophers, it was seen that all those who belonged to the empiricist current of philosophy of the timeLike Molyneux, Locke and Berkeley, they answered in the negative: the blind man would not be able to associate what he was seeing, on the one hand, with what he once touched, on the other. In the opposite sense, those who followed rationalist positions tended to give affirmative answers, so there was no way to get a unanimous solution.

A part of the philosophers thought that a person deprived of the sense of sight from birth could respond directly at the moment in which he could observe objects. However, the rest were of the opinion that the person would need to make use of his memory and his reason, and that even he should be able to observe all sides of the objects walking around him.

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What do the studies say?

Despite the impossibility of carrying out scientific studies that could solve the Molyneux Problem, in 1728, the English anatomist William Cheselden published the case of a child with congenital blindness that he had been able to see after a cataract operation.

Throughout this case it is stated that when the child was able to see for the first time, he was not able to recognize, through sight, the shape of things, and that he could not differentiate between various objects.

Some philosophers, including Voltaire, Camper or Berkeley, considered the English doctor's observations to be obvious and irrefutable, thus confirming the hypothesis that a blind person who regains sight is not able to differentiate objects until he learns to watch.

However, others were skeptical of these tests. They considered that it was possible that the child had not been able to make valid value judgments because his eyes weren't working properly yet and that it was necessary to give him a little time to recover. Others also pointed out that the boy's intelligence could also influence the validity of his answers.

Modern approaches to the thought experiment

Throughout the 19th century, all kinds of stories and studies on cataract operated patients were published that tried to shed some light on the Molyneux Problem. As expected, results of all kinds appeared, some in favor of the Cheselden results and others against. Furthermore, these cases were impossible to compare, since the pre- and post-operative circumstances were quite different. As a consequence, the Molyneux Problem was debated very frequently, without achieving any kind of agreement on its solution.

As for the Molyneux Problem in the 20th century, it focused on historical reviews and biographies of those philosophers who analyzed it and proposed solutions for it. Over the years, this enigma has come to cover all kinds of scientific fields like psychology, ophthalmology, neurophysiology and even in mathematics and art.

In 1985, with the incorporation of new technologies in the health field, another variation to the Molyneux problem was proposed. In this it was questioned whether the visual cortex of a congenitally blind patient could be electrically stimulated in a way that the patient perceived a pattern of light flashes in the shape of a cube or sphere. However, even these methods have not been able to establish a sure answer to the question.

The problem that could never be solved

We are pretty sure that at no time was Molyneux aware of the stir that his question would cause throughout history. In this sense, it can be concluded that the Molyneux Problem is one of the most fruitful and productive thought experiments proposed throughout the history of philosophy, which he is still shrouded in the same mystery as when Molyneux raised it in 1688.