The idea that human history is approaching a "singularity" -- that ordinary humans will someday be overtaken by artificially intelligent machines or cognitively enhanced biological intelligence, or both -- has moved from the realm of science fiction to serious debate. Some singularity theorists predict that if the field of artificial intelligence (AI) continues to develop at its current dizzying rate, the singularity could come about in the middle of the present century. Murray Shanahan offers an introduction to the idea of the singularity and considers the ramifications of such a...