Molyneux’s Problem – Can You Really Solve This Challenge?

Molyneux’s problem originated as a philosophical thought experiment in the 17th century. It involves a simple question encompassing the human senses of sight and touch.

Imagine a hypothetically blind person who has never been able to see ever since her birth. All through her life, she has learned to differentiate between different shapes of objects (such as a cube or a sphere) by the sense of touch alone. Now, imagine that this person suddenly gains vision and is able to see. The question posed is:

“Would she be able to immediately recognize shapes (such as a cube or a sphere) by her newly gained sight alone before she touches them?”

This simplified description pretty much captures the essence of Molyneux’s problem. Even though the problem description is simple, it leads to a complex set of consequences. In this essay, we will breakdown the challenges that reveal themselves as we try to solve Molyneux’s problem. While we are at it, we will also cover work done by some of the finest human brains on this topic.

But first, let us take a look at the historical origin of Molyneux’s problem.

This essay is supported by Generatebg

The Origin of Molyneux’s Problem

William Molyneux was an Anglo-Irish philosopher-writer who had a blind wife.

So, he was naturally curious about the challenges of blindness. In 1688, he wrote a letter to his fellow philosopher, John Locke, asking the following question:

“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 is the sphere. Suppose then the cube and the sphere placed on a table, and the blind man made to see: query, Whether by his sight, before he touched them, he could now distinguish and tell which is the sphere, which the cube?”

— William Molyneux

John Locke responded to this query from Molyneux in his famous publication: “An Essay Concerning Human Understanding.”

Locke’s essay kicked off a long history of debates around this problem which involved some of the best thinkers in history. Roughly speaking, philosophers and scientists were divided between two camps.

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Molyneux’s Problem — Rationalists Vs. Empiricists

Epistemology is a branch of philosophy that investigates the nature of human knowledge. In epistemology, rationalism and empiricism are two ways in which one could attain knowledge. Rational knowledge is obtained through reasoning and deduction whereas empirical knowledge is obtained through real-world experiences and observations.

Locke took the empirical approach when answering Molyneux’s question. He believed that a life-long blind person who gained sight would not immediately be able to recognize shapes based on sight alone. This is because they would have never learned to correlate visual features to haptic (touch) features. He wasn’t alone in his stance though.

Philosopher George Berkely argued strongly for sensory individuation: a notion that each sense is metaphysically unique. As a consequence, concepts acquired from different senses would be perceived differently by the human brain.

For example, the concept of a ‘seen line’ would be different from a ‘touched line’. As long as a person has not learned to correlate these two concepts via empirical experience, they would not be able to recognize the ‘seen line’ immediately via sight alone provided they were blind until that point.

Polymath Gottfried Wilhelm Leibniz also joined the debate and took a rationalist stance. He argued that a formerly blind person would be able to differentiate between shapes using skills of reasoning and deduction alone.

For instance, a sphere has the property that it looks the same when perceived from different angles, whereas a cube looks different from different angles. Similarly, such a formerly blind person would need to employ geometrical and logical reasoning to correlate their touch sensations with their newly acquired visual sensations.

This debate went on for a while until the empiricists came up with reasonable experimental results.

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Empirical Experiments to Solve Molyneux’s Problem

In 1728, English surgeon William Cheselden published a report where he successfully operated on a 12-year-old boy to cure him of cataracts. Following recovery, according to Cheselden’s report, the boy was unable to convincingly recognize shapes without having to touch the objects and correlate his visual and haptic senses first.

While this seemed like telling evidence, rationalists argued that there was room for error with such small sample size and potentially questionable mental capabilities (the rationalists apparently didn’t go easy on the poor boy).

Fast forward to the present, in 2011, Held et al. (reference link at the end of the essay) conducted an experiment where multiple subjects in the age-range of 8–17 were subject to tests before and after cataract-removal surgery. Immediately after their respective surgeries, these patients were subject to simple object recognition tests. Results revealed that their accuracy was hardly better than chance (around 58%).

On the contrary, when the subjects were tested a few days after their surgery, their accuracy had improved significantly. This showed how quickly the subjects were able to synchronise their senses and correlate sensory inputs (haptic with touch) in the brain.

Based on this, could we conclude that Molyneux’s problem is sufficiently solved and the answer to his question is ‘no’? Not quite. Cue in SSDs.

Sensory Substitution Devices (SSDs)

Bach-y-Rita invented a device called “BrainPort” which simulates sensory experiences of the sense of vision in experiences of the sense of taste. The BrainPort takes information from a mobile camera and transfers the signals to an electrode array on the tongue.

Seemingly just anecdotal evidence, BrainPort users claim that after a period of accommodation, they feel as if they can see using the device via their tongue. On the other hand, there is evidence that when people with congenital (life-long) blindness use devices such as BrainPort, areas reserved for visual processing in the brain are activated.

Experimentation with such devices reveals that a blind person may recognize shapes by using an augmentation device.

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Conclusion

Although empirical evidence points towards an answer to Molyneux’s question, it is still not sufficient to claim that Molyneux’s problem has been solved. Part of this has to do with how Molyneux framed the question and how scientists and philosophers understand it.

A congenitally blind person who suddenly gains sight is likely overwhelmed by the influx of information and is probably not in the best mental and physical state to differentiate between shapes and recognize the depth of vision. On the other hand, as time passes, the person learns to correlate the sense of touch with the sense of sight. So, a perfect experimental setup to solve Molyneux’s problem might very well be impossible.

Having said this, Molyneux’s problem inspires scientific thought and experimentation even today. This in turn leads to progress in terms of our understanding of human senses. As one of the consequences, people with congenital or incurable blindness are getting access to better and better technological solutions that help them ‘sense’ the world around them.

In this sense (pun intended), even though Molyneux’s problem might not ever be sufficiently solved, it functions as a key motivational factor for many scientists and deep thinkers to explore new areas in science and come up with ever more helpful technological solutions for humanity in the process!

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References: John Locke (philosophical essay), William Cheselden (medical report), Held et al. (scientific paper), and Michael Abrams (article on BrainPort invented by Bach-y-Rita)

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Further reading that might interest you: Can You Really Solve The Staircase Paradox? and How To Hear Acceleration Without Modern Technology?