The Scripture Is False And The Biblical God Is Dead.

[BrianSoddingBoru4]

all it really demonstrates is that they're using a secondary pathway that doesn't correspond to normal visual perception but clearly is perception nonetheless.

What do humans need normal visual perception for if they can function without it?

Because it's an evolutionary advantage. Humans with normal visual perception are less likely to be eaten by bears, and consequently more likely to pass on visual acuity to their offspring. The net result leads to fewer and fewer people becoming bear food, which gives them to time to invent things like agriculture and television.

Also, I suppose it would depend on how one defines 'function'. Blind people are certainly functional, but - let's face it - there are some things at which sighted people are better equipped to do.

Boru