The 'decline of political theory' refers to a significant debate within political science, particularly prominent in the mid-20th century, suggesting a period where traditional normative and philosophical political inquiry lost its prominence and vitality. This perceived decline was attributed to several factors:

Firstly, the rise of positivism and logical empiricism in the social sciences led to a focus on empirical observation, verifiable data, and scientific methodology. Political scientists increasingly sought to emulate the natural sciences, prioritizing 'facts' over 'values.' Normative questions about how society ought to be structured, which are central to classical political theory, were deemed unscientific, subjective, and therefore outside the legitimate scope of academic inquiry.

Secondly, the emergence of behavioralism in political science further solidified this trend. Behavioralists aimed to study political phenomena through observable behavior, quantitative analysis, and the development of testable hypotheses. This approach shifted attention away from grand philosophical questions about justice, liberty, or the ideal state, towards analyzing voting patterns, political attitudes, and institutional functions using empirical methods. The focus became 'what is' rather than 'what should be.'

Thirdly, some scholars pointed to the exhaustion of traditional ideologies and the perceived triumph of liberal democracy after World War II, leading to a sense that the major theoretical questions had been settled. This 'end of ideology' thesis, articulated by thinkers like Daniel Bell, suggested that the grand narratives and ideological conflicts that fueled political theory were diminishing.

However, the notion of decline was met with strong counter-arguments and a subsequent 'revival' of political theory. Critics argued that divorcing political science from its normative and philosophical roots rendered it sterile and unable to address fundamental societal problems. The rise of new challenges (e.g., civil rights movements, environmentalism, global inequality) and the limitations of purely empirical approaches demonstrated the enduring need for normative inquiry. Thinkers like John Rawls, with his 'Theory of Justice' (1971), are often credited with spearheading this revival, re-legitimizing the pursuit of normative questions and demonstrating the rigor with which they could be addressed. Today, political theory continues to be a vibrant field, engaging with both classical texts and contemporary issues, and integrating normative, conceptual, and historical analysis.