Peter Singer applied utilitarian philosophy to animal welfare, arguing that the capacity to suffer — not species membership — is the morally relevant criterion for moral consideration.
Utilitarian philosophy provided the first rigorous philosophical framework for animal welfare in the modern era. By identifying sentience and the capacity for suffering as morally sufficient grounds for consideration, it bypassed traditional arguments that only rational language-using beings deserved moral status. The utilitarian case for animal welfare does not require animals to have rights or dignity in a human sense — it requires only that their pain and pleasure be counted in moral calculations. This makes it a powerful and widely accessible philosophical foundation for welfare reform.