This was an original thought about 6 years ago or more, but then i found out someone had already thought about it. :(

the colors we see, through our eyes, how can we be sure other people see the same colors? maybe what is green to me, is really a red to you. but we have learned different names for the same color. you may think an red grass and a purple sky sound weird and unnatural, but maybe that is what someone else is used to, and that is what we base "natural" on.

so one argument is that the way the spectrum is layed out, colors cant just be switched with another, meaning there are lots of different shades of colors, and inbetweens involved. just like when you take a negative of a picture. when you invert the colors, you see a lot of blue and green and black. certainly no one can see that normally and still be able to think we all see the same colors.

enter color blindness. maybe color blindness is just the case above. it is the case when the colors are "switched" in such a manner that the colors can not be fully seen. until we have the ability to look through other peoples eyes, without the use of our own eyes then we will never be able to tell. it may even be the case that our brains interpret the color differently. and it has nothing to do with our eyes at all.