David McMenemy explores the intersection of political philosophy and professional ethics in library and information advocacy, detailing three main theories of social justice: maximizing welfare, protecting individual freedom, and promoting virtue. He emphasizes the importance of engaging with these philosophies to navigate current debates, such as the role of public libraries, and suggests that advocacy should reflect and respond to emerging political philosophies. The presentation highlights the need for libraries to adapt to changing societal values while maintaining essential services that support equality and community engagement.