Do bacterial species exist?
Any of my friends or colleagues who have had the "pleasure" of talking about science with me for more than a few hours know that I am prepared, at the drop of a hat, to rant extensively about several standing debates in biology which I consider merely semantic. For instance:
Q: Are viruses alive?
A: Who CARES!? Viruses do what they do. Cellular organisms do something else. What difference does it make if we decide to allow our middle-schoolers to draw little dotted lines around animals, bacteria, and viruses? And I don't even want to hear the word "prion".
I have a similar level of disdain for people who try to decide on a single definition for "species". Ultimately I am a pluralist: the definition should be tailored to the scientific question. Paleontologists, you have your morphological species concept, because what else do stony fossils allow? Are you studying speciation …