"PHILOSOPHICALLY SPEAKING...":

What color is a tennis ball? Answering this seemingly trivial question draws on two areas of philosophical inquiry: philosophy of mind (Can we ever really know how someone else experiences color? Does an image in our mind's eye -- in this case an ideation of a tennis ball -- accurately reflect the properties of a physical object?) and philosophy of language (What does it mean when we say "yellow" or "green" anyhow? Within the same language, can my "green" mean the same thing as your "yellow"?).

This article from The Atlantic looks at this issue and concludes, "Here at The Atlantic, the great tennis-ball debate eventually tapered off. ... But there would be no consensus. Yes, we would move on, continue working alongside each other, but we would hold onto our allegiances, team green and team yellow, like coats of armor. The color of a tennis ball is, and would remain, in the eye of the beholder. My colleague Julie Beck summed up the ordeal with a sentiment we could all agree with. 'It is truly horrifying every time it gets pointed out that we’re all walking around thinking we share the same reality,' she said. 'And we just are not.'" www.theatlantic.com/science/archive/2018/02/what-color-tennis-ball-green-yellow/523521/