. The “cognitive by-product theory” argues that religious belief is a side effect of cognitive skills that evolved for other reasons. It pays, for example, to assume that all events are caused by agents. The rustle in the dark could be the wind, but it could also be a predator. Running away from the wind has no existential consequences, but not running away from a predator does. Humans who ran lived to pass on their genes; those who did not became carrion.

. The “cognitive by-product theory” argues that religious belief is a side effect of cognitive skills that evolved for other reasons. It pays, for example, to assume that all events are caused by agents. The rustle in the dark could be the wind, but it could also be a predator. Running away from the wind has no existential consequences, but not running away from a predator does. Humans who ran lived to pass on their genes; those who did not became carrion.