Tom Kelley's “The Art of Innovation” wrote about people who dismiss brainstorming, and he says they "overlook the possibility that brainstorming can be a skill, an art, more like playing the piano than tying your shoes."
I read it and thought about every bad session I have ever sat in. Including the ones I ran.
Because the honest thing to say is that the sceptics have evidence. In 1987, Diehl and Stroebe published a study showing that groups brainstorming together generate fewer ideas than the same number of people working alone. The main reason has a name, production blocking. Only one person speaks at a time, and while you wait, your idea gets forgotten, downgraded, or talked over by someone more senior.
That finding is real and it is inconvenient and I think most people who quote it have drawn exactly the wrong conclusion from it.
Every one of those groups was untrained. That is what was being measured. And we took the result and used it to retire the whole method, which is a bit like concluding pianos do not work because a room of people who have never played one made a terrible noise.
Here is the part I keep sitting with.
Tying your shoes is something you can do. Playing the piano is something you become able to do. We put brainstorming in the first category. We schedule it like a meeting, staff it with whoever is free, give it no preparation and no facilitator, and then feel personally let down when nothing good comes out.
Nobody would run a company's finances that way. Nobody would run a hiring process that way. But ideas, the actual raw material of every product you will ever ship, we leave to an unprepared hour on a Thursday.