On 22/02/2017 4:03 AM, wrote:

But categories do matter, and so do the definitions we use to arrive at those
categories. The fact that people (even experts like the scientists at NASA) go
back and forth on what definitions we should use doesn’t make them less
meaningful. It just means that we’re still learning. That’s what science is all
about: we have to be able to adjust our definitions to fit our understanding. And
this whole Pluto business is a perfect example."

The issue of whether Pluto is a planet is purely a definitional matter
and has nothing to do with science.

Sylvia.