Consider this dialogue:

A: “All fish breathe through gills rather than lungs.”

B: “But whales are fish, and they breathe through their lungs.”

A: “Whales may look and seem like fish, but they aren’t truly fish because they breathe through their lungs.”

To anyone with a rudimentary knowledge of biology, A’s reasoning here must seem sound. Yet among some philosophers with a scientific bent, the structure of the reasoning A employs is often criticized as a logical fallacy. Continue reading →