Historically, sentience has been fairly easy to define. Humans
are sentient; animals are not. Prior to the twentieth century,
humans were the only beings that could write poems, perform
mathematical computations, and make complex machines. Therefore,
only humans were sentient. However, with the rise of computers,
sentience becomes harder to define. It is now possible to write
a computer program that can carry on a conversation so
skillfully that it is difficult, if not impossible, to
distinguish its responses from those of a human. Can such a
program be defined as “sentient”? Phrased more generally, the
question becomes, “Can any artificial life form really be
considered alive?” The 1980′s movie Blade Runner seems to answer
in the affirmative. Blade Runner is the story of a future world
in which genetically engineered “replicants”–artificial life
forms designed to be indistinguishable from humans–are used as
slave labor on off-world colonies. The only way to distinguish a
human from a replicant is to administ