The Solution to an Unanswerable Question

“If a tree falls in the forest,” the question begins, “and no one is around to hear it, does it make a sound?” That riddle has been around for centuries; the history is murky but it dates back to at least the early 1700s. It’s a question which, by its very design, isn’t intended to bring about a universally agreed-upon answer. Rather, the point of this question and many other, similar thought experiments is to provoke a broader conversation around the limits of human understanding.

But what if, one day, our collective knowledge and technology allow us to (somehow) answer questions like these? As it turns out, that’s already happened.

The question isn’t the tree/forest one, though. In 1689, an Irish philosopher named William Molyneux concocted the following problem (via Wikipedia):

If a man born blind can feel the differences between shapes such as spheres and cubes, could he, if given the ability to see, distinguish those objects by sight alone, in reference to the tactile schemata he already possessed?

When Molyneux first devised the question (now, uncreatively, called “Molyneux’s problem”), it — like the tree/forest question — seemed unanswerable. His hope was to get others involved in a discussion about how our minds work, and he was successful in doing so. Molyneaux first posed the question in a letter to another philosopher, John Locke, who replied that no, the once-blind, now-sighted man wouldn’t be able to differentiate between the shapes by sight alone. Others chimed in with a wide range of opinions and for centuries, philosophers debated the question. At no point did they reach consensus, and despite Locke’s take, the question was left unresolved. We don’t know if our sense of touch paints a picture in our mind’s eye which matches what we see.

Or, rather, we didn’t — until about 2011.

That year, per the New York Times, “researchers tested five subjects from rural northern India, four boys and a girl ages 8 to 17, all of whom had been ‘blind since birth.'” But had these children grown up in a more developed area, their vision would have been improved through advances in medicine. The subjects’ blindness was caused by cataracts (or in one case, a damaged cornea), and the research team was able to improve their vision — and did. The Times explains:

Before their operations they could perceive light, and two could discern its direction, but none could see objects. Afterward, they all had vision measured at 20/160 or better, good enough to distinguish objects and carry out the tasks of daily living.

That improvement included giving them the ability to see the shapes — spheres and cubes — that they could, previously, not discern. As a result, we were able to put Molyneux’s to the test. And it turns out that Locke was right: the children couldn’t tell the difference between the shapes by sight alone.

As for that tree falling in the forest? That’s still hotly debated.

Bonus fact: If you want to watch TV in the United Kingdom, you can — provided you pay about £150 per year, per household for a television license, the proceeds of which are used to fund the BBC. That fee seems unfair for the blind, as the experience isn’t quite the same. (That’s not a joke; blind people can, somewhat, enjoy the programs that sighted people enjoy regularly, through assistive software and the like.) The solution? Households of blind people can apply for a 50%-off discount on the TV license.

From the Archives: Temporary Blindness: We’re all blind for a few moments each day.