When One Person Becomes Two

Marya Schechtman picks up where her previous lecture left off, turning a critical eye on the psychological continuity theory of personal identity. While widely held, this theory faces serious challenges, many of them arising from the same types of sci-fi thought experiments that once seemed to support it. Schechtman walks through the teletransportation case, the branch line scenario, and the fission problem, where one person apparently becomes two. Through the triplets thought experiment involving Jill, Lil, and Till, she shows why personal identity must be a one-to-one relation and why several intuitive answers to the fission problem fail. She then introduces Derek Parfit's radical suggestion that identity is not what matters in survival, and his reductionist view of persons. The lecture also considers the biological criterion as an alternative, raising questions about whether "person" is really a kind of thing or merely a phase in the life of a human organism. Schechtman highlights strengths and weaknesses on all sides, setting the stage for alternative approaches in the next lecture.