Blind people can't verify the existence of a rock?Let's take a rock for example. We understand that rock is present at a particular location when sufficient light is able to illumine it and we have a capable set of eyes to see it. Other than that - if light is not sufficient or we are blind - we can only conceptually understand a rock - but never verify its existence.
I wonder if they know that?
Does the same hold for pencils? People? Their guide dog? Or is it just rocks?
Right. Here's an experiment: throw a rock at a blind person and a sighted person*. Check and compare the reactions/ effects when they are hit.Coming back to the rock - how do we know it really exists - even if we hold it in our hands and can see it etc. Because our connection with the rock is through the image that's formed in the back of our heads (retina). The same goes for every tangible object including our own bodies. If that image is not being formed - the "reality" of a lot of things would come into question.
As a control throw a rock at a sighted person from behind. Check and compare reaction/ effect.
* Of course you'll need volunteers with pretty good control over their reflexes, so that they don't dodge. But, hey... tell them it's for science.