Introduction: The ethical debate over abortion represents one of the most enduring and philosophically significant controversies in normative ethics and bioethics, engaging fundamental questions about life, autonomy, responsibility, intention, consequence, and human flourishing. The traditional doctrine of double effect (DDE), rooted in Thomistic moral theology, has long served as a central tool for analyzing such cases by distinguishing between outcomes that are intended and those that are merely foreseen. Philippa Foot’s seminal critique of this doctrine marked a decisive shift in the philosophical landscape. She argued that the intention/foresight distinction, while psychologically relevant, fails to capture the moral difference between permissible and impermissible actions and that ethical assessment should instead focus on the structure and hierarchy of duties embedded within human life. This reorientation transforms the abortion debate and prompts a broader rethinking of the foundations of moral theory.
Findings: Foot’s analysis develops along two interrelated dimensions. At the first level, she emphasizes the priority of negative over positive duties and shows how this distinction accounts for many of our core moral intuitions. Negative duties — such as prohibitions against killing or harming — carry greater moral weight than positive duties like helping or benefitting. This explains why “letting die” and “killing,” even with identical outcomes, may be morally distinct. At the second level, Foot’s later theory of Natural Goodness grounds ethical judgment in the teleological structure of human nature and the biological ends of the species. Moral evaluation, on this view, is not merely a matter of individual actions but must be situated within the broader framework of species-specific flourishing. Human life, as a rational and social form of life, involves functions such as reproduction, parental care, social development, and the cultivation of virtue. Abortion must therefore be assessed not simply as the termination of fetal life but in relation to whether it contributes to or undermines these fundamental ends. Foot’s approach 
also offers implicit responses to major criticisms. Warren Quinn’s account of the causal role of intention, James Rachels’s rejection of the act/omission distinction, and challenges based on the naturalistic fallacy all receive nuanced treatment. Foot shows that intention, though morally relevant, is not decisive; that the act/omission distinction reflects a deeper structural difference; and that normativity and nature are not separate domains but interconnected aspects of a teleological order.
Discussion: Foot’s contribution has far-reaching implications for both ethical theory and practical decision-making. It moves beyond reductive approaches — whether intention-based or consequentialist — toward a more objective, context-sensitive model of moral reasoning. By rooting ethics in human nature and the concept of flourishing, her framework provides criteria that are simultaneously more objective and more flexible, suitable not only for the abortion debate but also for broader issues such as euthanasia, reproductive rights, and medical decision-making. The resulting vision of ethics is one in which duty, telos, and virtue are not competing paradigms but mutually reinforcing dimensions of moral life. Abortion is thus reinterpreted not as a purely legal or emotive issue but as a focal point for examining the interplay of nature, normativity, and the meaning of human existence. This synthesis is what makes Foot’s position one of the most profound and enduring contributions to contemporary moral philosophy.