The way I see it, we've evolved to see "white" things illuminated during the day as "white".
As they are illuminated both by the sun and the blue scattered light from the rest of the sky, the color we percieve as white is the color of the sun with some blue added, which is why the sun itself looks slightly yellow.

Had we evolved under a different star, or in an atmosphere with a different composition, I believe we'd have had an intensity curve experienced as white, but it would be very different from the one here.

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It would be hard to imagine an uglier building that hadn't won a major architectural award.
Trying to make sense of computers, The Error Log.