The Sentient Arc: Ethical Weight Across Present and Future Sentient Experience

Existing frameworks for evaluating the ethical weight of harm to sentient beings treat present experience as the primary or exclusive locus of moral consideration. This paper argues that such frameworks are structurally incomplete. The ethical weight a sentient being carries is not a function of present experience alone but of two simultaneously compounding dimensions: fully realized present sentient experience and foreclosed future sentient experience. This construct-the Sentient Arc-is introduced and defended as a principled basis for evaluating moral weight across all sentient beings. The paper grounds the construct empirically in universal mourning patterns across recorded human history, argues that these patterns reflect a deep feature of sentient ethical cognition rather than cultural convention, and positions the Sentient Arc as a universal metric applicable across biological and, as evidence develops, artificial entities. The construct is presented as an original contribution within The Four Intuitions ethical framework (Sheraton, 2026) and as a standalone theoretical tool for applied ethics and moral patienthood research.