In “What Are Little Girls Made Of?” (1-7) the Enterprise visited the planet Exo III and found Dr. Roger Korby, who had not been heard from in five years. As it happens, Korby was once engaged to Nurse Christine Chapel, who was overjoyed to have found him. As the episode unfolded we learned that years earlier, with his body dying, Korby’s memories, knowledge and personality—his “soul,” he suggested—had been transferred into an android body. This became known when Korby’s android hand was damaged during a fight, revealing circuits under his artificial skin. Responding to Nurse Chapel’s apparent dismay at the sight, Korby said imploringly, “It’s still me, Christine—Roger—I’m in here.” However, Chapel and Kirk both rejected this identification. After “Korby,” in despair, dematerialized himself (and a female android assistant) with a phaser, Spock arrived on the scene and asked, “Where is Dr. Korby?” Kirk replied, “Dr. Korby was never here.” But could the android have actually been Dr. Korby?

The issue just raised is discussed under the rubric personal identity in philosophy. In An Essay Concerning Human Understanding (1690),¹ John Locke defends a theory of personal identity that would allow transfers such as the one Korby underwent to be transfers of a person. Locke argues that the continued existence of a person does not essentially involve the continuance of any entity or object, such as a body, brain or non-physical soul. Instead, a kind of pattern is transmitted—in particular, the patterns that encode memories—and this process (the transmission of memories)  …