When you want to know about treatment options for high blood pressure, you go to a doctor. When you want to know who ran the Underground Railroad during Civil War times, you go to an encyclopedia. When you want to know about a person's credit history, you go to a credit reporting agency.
But when you want to know whether you can start a sentence with a conjunction, you go to eight or 10 friends who don't know either, launch a big debate in which everyone puts in his two cents and you all go back and forth for hours. When you're done, you're no closer to an answer than you were when you started. But you probably think you are.
When I gave a talk about grammar at Portland's Wordstock Festival in April, an attendee shared a story about how a writing group she once took part in spent an entire session debating a single word in a script title: "whose." Some said it should have been "who's." Others made counterarguments. All of them pontificated about the difference. Then two hours were gone and they never got around to discussing the script. And they never figured out whether it should have been "whose" or "who's."