This document summarizes and analyzes Judith Thomson's essay "A Defense of Abortion". It argues that Thomson uses strong analogies to challenge arguments for banning abortion based on the premise that life begins at conception. The summary defends Thomson's position, stating that her analogies make her argument difficult to criticize. It notes that Thomson uses three major analogies, including the famous "Violinist Analogy", to illustrate different scenarios where abortion would be considered acceptable even if fetal personhood is accepted. The document evaluates criticisms of Thomson's argument and concludes she has established abortion rights on the basis of her reasoning and use of compelling analogies.