Ask the Box

30 aug 06

"why was the color red chosen to represent stop and green chosen to represent go?"

have you ever heard of the philosophical problem of buridan's ass? it's about an ass who arrives at two bowls of water on the ground, each the same distance from him. he has no reason to pick one over the other, so instead he stands there and dies of thirst.

if we have no reason to pick red for "stop", or green for "go", does this mean that we're paralyzed and don't choose anything? why does there have to be some definitve causality or purpose behind every action? sometimes things just happen according to the laws of probability, or perhaps the subconscious mind.

that said, the question has already been answered by cecil adams. apparently, blood-red has been used for centuries for stop, danger, go no further, etc. but as far as the other colors go, we can re-consider buridan's ass, although perhaps not entirely.

this is one of those questions, like the woodchuck question, the swallow question, the tootsie roll question, the parking-on-a-driveway question, and the downside-up question, that occupies a social location of sorts. i'm willing to bet lots of people have wondered about red and green lights.

questions like these -- "stumpers" -- can generally be answered with a few google searches (or logical trains of thought), and tend to produce really short responses. if you're (un)lucky and i'm in a verbose mood, i'll go on to talk about the nature of such questions, or something arguably related to the question.

so, red was "stop". for "go", the railroads' chose a white light, ie, a light without a colored lens attached, which makes some conceptual sense: it's a clear light, without an obstruction -- "all clear". cecil tells us that this presented problems, since lenses could fall off of colored lights and make them look like "all clear" lights; he mentions an incident of this and the ensuing train disaster. i feel like an idiot paraphrasing his entire column. so, the sense-making "clear" light was replaced with green. cecil doesn't know why "green", particularly, but i do.

i'm inclined to think green was chosen because it's roughly the chromatic opposite of red -- there's no way anyone is going to confuse red with green. "orange" is the precise chromatic opposite, but an orange light would have been hard to make exactly "orange". and who's to say it's not? a red light looks orange, or red, or dark red, etc, depending on the strength of the bulb, opacity of the lens, and other light shining on it. it's "opposite enough" so that no one is ever going to confuse it for green -- as opposed to blue or yellow, both of which are immediately continuous with green. check out a color wheel.

now that you know about "the straight dope", you can stop reading "ask the box". i'm so ashamed.

however, in "ask the box", you can ask me about my pet dog (which i will answer within a few days), whereas cecil adams won't answer you if you ask him something like that, let alone, won't answer any question for years at a time (see #20). at this point, i must encourage personal questions. send me personal questions! i need a hedge up on cecil adams, that bastard.