Peter Singer – Expanding the Moral Circle

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Peter Singer – Expanding the Moral Circle

Source: Animal Liberation (1975); Practical Ethics (1979)

Summary: Singer argues for extending moral consideration to non-human animals based on their capacity to suffer. Sentience—not species—is the ethical threshold.

Resonance with PET: PET expands moral consideration beyond species boundaries. Both recognize that capacity matters.

Divergence: PET may assign relevance to systems that lack sentience but show recursive survival behaviour, and withhold it from sentient beings without a self-model. This is a structural, not moral, judgment.