More precisely, the notion that there are simple answers to complex problems. The universe is complicated. Whether you are interested in the functioning of a cell, the ecosystem in Amazonia, the climate of the Earth or the solar dynamo, almost all of the systems and their impacts on our lives are complex and multi-faceted. It is natural for us to ask simple questions about these systems, and many of our greatest insights have come from the profound examination of such simple questions. However, the answers that have come back are never as simple. The answer in the real world is never "42".
Yet collectively we keep acting as though there are simple answers. We continually read about the search for the one method that will allow us to cut through the confusion, the one piece of data that tell us the 'truth', or the final experiment that will 'prove' the hypothesis. But almost all scientists will agree that these are fool's errands—that science is method for producing incrementally more useful approximations to reality, not a path to absolute truth.
In contrast, our public discourse is dominated by voices who equate clarity with seeing things as either good or bad, day or night, black or white. They are not simply ignoring the shades of gray, but are missing out on the whole wonderful multi-hued spectrum. By demanding simple answers to complex questions we rob the questions of the qualities that make them interesting, reducing them to cliched props for other agendas.
Scientists sometimes play into this limiting frame when we craft our press releases or pitch our popular science books, and in truth it is hard to avoid. But we should be more vigilant. The world is complex, and we need to embrace that complexity to have any hope of finding any kind of robust answers to the simple questions that we, inevitably, will continue to ask.