The Problem of Other Minds in Machines

If I cannot know whether another human experiences a mental life in some way comparable to my own, how can I know whether a machine experiences one?

"It looks as if no scientific answer can be expected to the question of how or why we differ from a mindless body that simply behaves exactly as if it had a mind. The good news is that this difference makes no objective difference; the bad news is that it continues to make a subjective difference, one that cannot be explained away."

--Stevan Harnad, "Other bodies, Other minds: A machine incarnation of an old philosophical problem," Minds and Machines, 1991