Open calls solicit new ideas for a clearly specified goal. They work on problems where the solution is easier to check than create.
In the human computation problems described in the previous section, the researchers knew how to solve the problems given sufficient time. That is, Kevin Schawinski could have classified all million galaxies himself, if he had unlimited time. Sometimes, however, researchers encounter problems where the challenge comes not from the scale but from the inherent difficulty of the task itself. In the past, a researcher facing one of these intellectually challenging tasks might have asked colleagues for advice. Now, these problems can also be tackled by creating an open call project. You might have a research problem suitable for an open call if you’ve ever thought: I don’t know how to solve this problem, but I’m sure that someone else does.
In open call projects, the researcher poses a problem, solicits solutions from other people, and then picks the best. It may seem strange to take a problem that is challenging to you and turn it over to the crowd, but I hope to convince you with three examples—one from computer science, one from biology, and one from law—that this approach can work well. These three examples show that a key to creating a successful open call project is to formulate your question so that solutions are easy to check, even if they are difficult to generate.