Philosophers are aware that "emergent" properties are philosophically puzzling. Similar puzzlement seems to have prompted something like the following from my daughter:
Atoms can't see, but if you bung a whole load together to make an eye, how can that eye see ?
How would you approach this question? I think whatever I said, I'd want to begin by saying that eyes can't see. People see, using their eyes. In many ways this may be mere pedantry, but I think it's fairly clear that as remarkable as eyes are, the wonder of sight happens somewhere "behind the eyes".