First off I don't know that it exists. It's impossible to know something is 100% true.
So what criteria or conditions need to exist then for you to say you actually know something? The fact that I have been using refracting telescopes which rely on the concept known as refraction of light to work gives me a clue about its existence.
It gives you a clue about it's existence. It does not PROVE it. In the event that we are just a giant simulation on a super advanced civilization's super computer refraction does not really "exist"
I guess for me to say that i know 100% that refraction exists is virtually impossible. What if a person is born and, when his brain creates images out of "refracted" light beams they don't appear out of place our out of position at all. That person has a much more significantly advanced visual cortex than your average human. To him the idea of "refraction" would be utter absurdity and we would all be insane for believing such a thing.
Remember this dress? Half the people who saw it said the dress was blue and black. The other half of people who saw it said the dress was white and gold. What is the TRUTH? Well the truth is that people have different visual cortex's, different eyes, and different optical nerves and see different things.
Remember this? A lot of people heard "Yanny" and many people heard "Laurel".
What is the TRUTH. What is the voice saying?
I believe my comment was directed more toward iamcpc, since they were the ones to argue that it is impossible to know something 100%. I don't know that I am not the only conscious being, but that doesn't stop me from making friends and having meaningful relationships, for instance. So claiming that you can't know something for absolute sure is no argument for or against anything.
This is not an argument. Someone asked what would need to happen for me to go from believing that refraction is real to KNOWING that refraction is real and the answer to that question is very complicated.
I'm not the one questioning whether refraction exists or not. I am simply telling iamcpc that I have been familiar with what I recognise as the refraction of light for over 40 years so I don't understand his need to question whether refraction exists or not.
If what I recognise as the refraction of light actually isn't refraction after all then perhaps he could explain to me how refracting telescopes work.
I've already explained that I believe there is a lot of evidence which suggest that it is very likely that images made in the average human visual cortex are affected by the path the photons take before the strike the optic nerve.
Do I KNOW 100% that this is the case? No I do not.