Have you thought of a clever product to mitigate climate change? Did you invent an ingenious gadget to light African villages at night? Have you come up with a new kind of school, or new ideas for lowering the rate of urban shootings?Thanks, but we have lots of those.

Whatever problem possesses you, we already have plenty of ways to solve it. Many have been rigorously tested and have a lot of evidence behind them — and yet they’re sitting on a shelf. So don’t invent something new. If you want to make a contribution, choose one of those ideas — and spread it.

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