I like this article. There's one part in particular I enjoyed, where the author is talking about how scientists work with concepts, and not definitions. Which is why Pluto was ultimately demoted. Scientists changed their concept of 'planet' after finding a whole bunch of other objects in the solar system. The concept of 'planet' no longer includes Pluto, which is fine. As N.D. Tyson says, "We put Pluto with it's brethren." Pluto is now the star of a whole new concept in the solar system.
'via Blog this'
This also clears up a misconception about the Linnean taxonomic system. We don't define animals, like the Desert Horned Lizard. Sure, we call it Phrynosoma platyrhinos, of the Family Phrynosomatidae, Order Squamata. But these classisifications are only concepts that help us find order and connection in the natural world. We do not define the natural world. But we do have conceptions about the world, and these conceptions help us to learn about the world. For example, because both the Desert Horned Lizard and Short-horned Lizard are in the Genus Phrynosoma I know that those two creatures are related. Why? Because the concepts of evolutionary biology and the Linnean taxonomic system.