Day by day, however, the machines are gaining ground upon us; day by day we are becoming more subservient to them; more men are daily bound down as slaves to tend them, more men are daily devoting the energies of their whole lives to the development of mechanical life.
—Samuel Butler, “Darwin Among the Machines,” 1863
Can machines ever be sentient? Could they perceive and feel things; be conscious of their surroundings? From a materialistic point of view the answer must surely be “Yes,” in particular if we accept that we ourselves are mere machines, albeit made from flesh and bones and neurons. But a point of view is not a proof: Only if we succeed in creating sentient machines can this question be answered definitively. But what are the prospects of achieving such a feat? Is it ethical to embark on such a path to begin with? And what...