This chapter examines six elements of Buchanan on liberty they are Buchanan's indeterminate contractarianism, Buchanan's critical constructivism, his subjectivist conception of economic value, Buchanan's perspectivist epistemology and Buchanan on liberty. Buchanan's system of ideas is an original contribution to political economy, synthesizing elements from a diversity of traditions Wicksellian, Austrian, and Chicagoan into a powerful and coherent body of theory. The proceduralist character of Buchanan's indeterminate contractarianism has three sources, in his mitigated scepticism and critical constructivism and in his value-individualism. The real difference between Buchanan's methodological commitment to Homo economicus and Becker's is far more fundamental: it is epistemological. Buchanan refuses to follow Hayek in generalizing the observed phenomenon of undesigned coordination in market exchange and extending and developing that observation into a theory of cultural evolution or institutional Darwinism. The dependency of Buchanan's social philosophy on the moral culture of Western individualism seems to me, also, at once unavoidable and not necessarily a weakness in it.