A few weeks ago an email was going around about how you could diagnose a stroke without any medical training just by answering three simple questions and get the person to the doctor in time for treatment.

I spoke to my colleague Andreas Brink about using that idea in another context, a little less serious one such as code. He said immediately that only one question is needed and that would take people without much development experience a long way. That question is "Is there any duplication?" Lots of other problems boil down to that simple question. I'm sure we can get Andreas to expand on this further...

Another similar question I've often heard is "Is that testable?" (but that requires experience in test automation). Do you have another favorite?