The human imagination is one of those abstract neural phenomena that tend to puzzle scientists, like dreams or voting Green Party. For what purpose did we evolve our imaginations, which have come to guide so much of human culture? Oxford professor and British Academy fellow Timothy Williamson ventures an explanation in the New York Times philosophy blog, The Stone. Williamson, writing both with scientific rigor and joke-ridden whimsy, says the imagination may have been a crucial tool for survival by early humans and our ancestors.

A reality-directed faculty of imagination has clear survival value. By enabling you to imagine all sorts of scenarios, it alerts you to dangers and opportunities. You come across a cave. You imagine wintering there with a warm fire — opportunity. You imagine a bear waking up inside — danger. Having imagined possibilities, you can take account of them in contingency planning. If a bear is in the cave, how do you deal with it? If you winter there, what do you do for food and drink? Answering those questions involves more imagining, which must be reality-directed. Of course, you can imagine kissing the angry bear as it emerges from the cave so that it becomes your lifelong friend and brings you all the food and drink you need. Better not to rely on such fantasies. Instead, let your imaginings develop in ways more informed by your knowledge of how things really happen.

Not only is the imagination an important survival tool, Williamson argues, but a poorly developed imagination could mislead early humans into potentially deadly situations. Therefore, those of our ancestors with the sharpest and most precise imaginative ability would be the most likely to survive and pass on their genes. The use of imagination has not waned with the passing centuries, he writes. "In science, the obvious role of imagination is in the context of discovery. Unimaginative scientists don’t produce radically new ideas. But even in science imagination plays a role in justification too. Experiment and calculation cannot do all its work."