Andrew Leland

Can you see what's wrong with this photo?

The answer that the people sharing the photo had is that the woman can't be blind.

If she is, why is she looking at her phone?

Blind people don't look at things.

The caption wants you to remember, blind people don't see.

And if she can see, what's she doing with that long white cane that signals to the world that she's blind?

Maybe she's trying to get sympathy that she doesn't deserve or trying to trick us somehow.

So, how blind do you have to be to be blind?

How much vision do you have to remove from the heap of sight before it becomes blindness?

People love binaries, especially people on the internet, which is a place that's not always very friendly to ambiguity.

This photo was shared more than 33,000 times, and I think it went viral exactly because of its ambiguity.

It illuminates a weird, paradoxical truth about blindness.

Blind people can see.

I don't mean this in the way that people mean it when they talk about Daniel Kish.

Kish makes clicking sounds with his mouth that he uses to navigate his environment, the way a bat uses sonar.

Brain scans show that when Kish navigates his environment this way, using his DIY sonar, his visual cortex lights up.

That's amazing, but the point I'm making is much simpler.

On the one hand, blindness is a binary.

You're either blind or you're not.

On the other hand, blindness is a spectrum.