Comment by mvr123456

Since it's an old debate that a lot of smart people spent a lot of time thinking about, the best short / simple answer you'll see for it is "you might want to read some more about it". A few keywords here are qualia, perception, descartes and the evil deceiver, berkeley and immaterialism, kant and synthetic a-priori, the nature of the reality of mathematical objects and mathematical truth, etc. If you think it's easy, for sure you have not understood the question yet.