I'm tired of sitting in brainstorm meetings where someone shares a perfectly good idea, and another person immediately uncorks the following: "Well, let's play devil's advocate..." and begins to blast that idea to shreds. That doesn't make your ideas tougher. It just kills them.
Instead of invoking the devil, think about your audience. We need to shift our frame of reference, in the context of our meeting, to make the call.
Here are some questions you can use to create context around your critiques and keep those great ideas on the table long enough to bring them to life.
If the devil's advocate is being employed, chances are you're already in the thick of a project, or at least far enough down the path that you have a pretty decent idea of your target audience. I like to consider the following before I open my mouth:
Did we describe our audience clearly at the start of the critique? Bring up your personas when you're looking to evaluate ideas. If the idea in question is floating out of context, then immediately recast the idea in a scenario -- with personas attached. However, if you don't have a persona...
Can you visualize your audience? It's one thing to describe the audience in demographic terms. Instead, can you talk about Janet, who's 42, loves to get pedicures, and is going to her 20 year reunion with her chihuahua Freddy on the passenger seat of her aging sports car? Can you get inside her mind? You should have this frame of reference before you start heavy critique. Otherwise, you're just going off gut feel. That only works half the time, and it can't be easily defended in a client review.
Can we let the ideas sit and bake in the oven? You don't always have to end the meeting with a clear picture of what's going to be executed. Taking time to let the work stew also gives you the space to judge the merits of an idea with fresh eyes and details about your audience squarely in mind.
If your client is part of the brainstorm and keeps shooting down ideas in process, be honest about the impact to their bottom line. You've been hired to come up with a raft of stellar concepts, and your client directly squelching those ideas is a waste of their money. If you're in a brainstorm with your client and the devil's advocate keeps coming out, call for a coffee break and start a chat with them outside about what's going on within the room. They may not like it, but they'll understand that while they're paying for the meeting, it's not "their meeting."
Separate of the devil's advocate coming up, there are some other ways to head off negative thinking from the get-go:
Did you state a desired outcome at the start of the meeting? A point of focus for everyone's feedback, such as, "We're looking for two strong concepts by the end of this meeting," can force constructive dialogue as opposed to destructive sniping. The devil's advocate often comes out if you don't clarify how to deliver your feedback. It's fair to pre-load each segment of your brainstorming session with dialogue about what behavior will allow the best working result.
Is it the right time for heavy critique? If you're still in brainstorm-land, is it really the proper moment to shear an idea away? Have a "no negatives" rule until you get very far down the path with your brainstorm.
Is the work being criticized just to kill it? It's all to easy to poke a hole in a balloon if all you do is carry around pins. As opposed to prodding the work with negatives, ask for rigorous critique, which is more like mashing and tweaking ideas than disassembling them. If someone's just naysaying, pull them from the meeting.
Do you need a sliding scale regarding how you critique the work? My wife told me ages ago about an animation studio where they would assign one to five eggs to an idea that was in process. When the idea had one egg assigned to it, you could only critique it at a very high level. As the work become more finished, it gained more eggs, and you could get more granular about your feedback. This system kept people from drilling into particulars or pre-loading negative impressions based on the amount of finish in the work.
As an aside: I've worked at agencies where we've used methods such as Edward De Bono's Six Thinking Hats. It can seem a little esoteric at first, but if you're doing a very long-form brainstorm, using those more sophisticated critiquing methods can force a higher level of rigor to how you explore the nooks and crannies of various conceptual ideas.