Friday, December 17, 2010

Poor Pluto

The demotion of Pluto from planet to dwarf planet (or planetoid) provides another example of the themes of my previous posts. Like the definition of "species", the definition of "planet" is vague, man-made, and changes over time. Scientific authorities also alter the membership of the category based on new information. These changes make many people (especially children) upset. I suspect changes to the planets also cause cognitive dissonance due to their ancient connections to astrology, mythology, and religion. The unchanging nature of heavenly objects was a bedrock belief: "as sure as the sun will rise." Yes, Pluto was not one of the original planets visible to the naked eye, but like the others on discovery it was given the name of a Roman (formerly Greek) god. Today people don't consciously remember how much of our daily language is based on past mythology. My favorite example (besides the planets) is the English names of the days of the week:

Sunday : Sun
Monday : Moon
Tuesday : Tyr (Norse god)
Wednesday : Woden / Odin (Norse god)
Thursday : Thor (Norse god)
Friday : Freya (Norse goddess)
Saturday : Saturn (Roman god)


Gemfinder said...

I'm testing whether the kids may grasp this better if exposed early.

They first needed the idea that language is arbitrary. Last week at dinner we did a thought experiment: what if their parents had always, from their children's birth, used the word "goo goo" instead of water. When the kids arrived at preschool, when thirsty, they would ask for goo goo. No one at school would understand, but everyone at home would. They found this hilarious.

That was the setup for this week, in which I asked why Pluto was no longer a planet. "Pluto hasn't changed," I said, "so what changed?" As you surmised, even with the idea planted that language is arbitrary, they still didn't guess that scientists had branched the definition of planet.

Eric Rollins said...

Interesting. Are your children multi-lingual? I think multi-lingual children would get the arbitrariness of words easier. But this post is about something more fundamental (which you may be working up to): the arbitrariness of categories. Multi-lingual speakers are aware of this because they realize there isn't a 1-1 mapping for many words, but they don't remember (or never knew) these differences exist because of divergence over time. This drift is "categorized" differently because it wasn't explicitly decided by some committee.

Note the attempt to find root categories is the heart of the essentialist project. Popper's great essay showing showing how un-productve this has been for science is linked (in a rare self-comment :-) off my "what's really wrong with Ayn Rand post.