Re: Polanyi on science (was Re: [asa] C.S. Lewis on ID)

From: Murray Hogg <>
Date: Mon Dec 01 2008 - 00:47:37 EST

Hi Moorad,

> Your statement, "yellow has an electromagnetic wavelength of 590 nanometers", is false. The correct statement is that most humans perceive the electromagnetic wave of wavelength of 590 nm as a color, which they call yellow. Notice that according to the Doppler effect, such waves will appear shifted to the red if the source is moving away from the observer. Therefore, one has to be rather careful in what one says.

Correction in linguistic usage noted - apologies for the slip.

On the substantial content of the above, however, I'm not at all sure why you introduce the Doppler shift into the discussion unless it is to infer (you don't state it outright) that our description of a light source as "yellow" is subjective because, under certain conditions brought on by the Doppler shift, we can refer to the same light source as "red" or "blue" or some other term. But I'll only say is that I consider it weakens your case substantially.

Let me explain what I'm thinking;

Lets say I see a yellow light, pull out my specrometer and measure its wavelength as 590 nm.

I then begin to move toward it at sufficient speed that it now appears blue. Correct me if I'm wrong, but if at the moment of observing this "blue" light I pulled out my spectrometer and took a reading of its wavelength, would I not get a reading of about 450 nm as is appropriate for "blue" light?

So, sure, the Doppler effect will alter the perceived color of a light source - but that's because it alters the wavelength relative to the observer. Such light sources don't just APPEAR shifted, they actually ARE shifted - relative to the moving observer, anyway.

Thus the implication that human perception is subjective because we refer to a light source as now "red", now "yellow", now "blue" depending upon our relative motion in respects of it misses the blatantly obvious rejoinder: a scientific instrument measuring the same light source concurrent with our observations will read now "700 nm", now "590 nm", now "450 nm".

So if we correlate color with EM frequency, it appears that our changing perceptions accord pretty well with what you're calling objective data.

I'm not sure how this correspondence between a group of mental concepts and the measured data HELPS maintain the distinction between one as subjective and the other as objective.

Let me say, at this point, that I don't think you could have picked a WORSE example upon which to build your case. Rather than arguing that the concepts "yellow", "blue", "red" are subjective and measurement of EM frequency using instruments objective, you would have been better arguing a parallel case for concept pairs such as "hot - cold", "bright - dark", "loud - quiet". In such instances you would have stood a far better chance of making your point as people often disagree whether a room is "hot" or "cold" even if they agree that it is 25 deg.C.

But in respects of color I'm sorry to say that our regular usage of color terms is simply too tightly specified for there to be much in the way of subjectivity involved. So when a person tries to tell me that "yellow" is "blue" I don't simply shrug my shoulders and put it down to subjectivity as I would when they claim a room I perceive as "hot" is perceived by them to be "cold". Rather I say that they are in error because we actually have an agreed standard of what constitutes "yellow" - it may be ambiguous to some degree - but at rock bottom I will maintain that there is no significant degree of subjectivity involved in the ascription of color to an object. We simply don't USE color terms in THAT sort of way.

Finally, I'd suggest this could even be determined by experiment: this Christmas, as opportunity arises, we ask people to identify the colors of a string of Christmas lights. If we get a significant variation in answer with no consistency in the terms people use to describe the color of the various lights, then the "color identification is subjective" thesis wins. If people consistently refer to the light emitting EM radiation at about 590nm as "yellow", at about 700nm as "red" and so on, then the "color identification is objective" thesis wins. I know betting is naughty, and if I do it Santa won't visit, but if I were a betting man...


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Received on Mon Dec 1 00:48:16 2008

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