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“I see trees of green,” croons Louis Armstrong. “Red roses, too.” He gazes up at skies of blue and clouds of white, then back down at the iridescent sea of humanity around him – and he marvels at the wonder of a world full of color, enduring despite the darkness lingering just over the horizon.

When I think of this song now, I’m tempted to think of it as an exercise in perspective: You can look at the bright side or the dark side of something, and one is just as real as the other. It’s all relative, and there are no absolutes – just attempts to persuade someone else to see things your way. Color is a prime example. Whether the dress was yellow and white or black and blue (remember that debate that tore the internet apart in 2015?) was, ultimately, up to the eye of the beholder.

But there’s a case to be made that colors are “as objective as length and temperature,” philosophers Elay Shech and Michael Watkins of Auburn University argue. And it doesn’t take all that much mind-bending to prove it. “To determine whether two objects have the same color, an observer would need to view the objects side by side against the same background and under various lighting conditions,” they write. Ask someone else whether those objects are the same color – and you’ll get some “compelling evidence” that “colors are objective features of our world.”

Do I see the same trees of green as Armstrong or you? Probably not – but it is wondrous, I agree, that color persists, no matter what shade is thrown upon it.

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