Freedom, according to the philosopher Isaiah Berlin, can be thought of in a negative and a positive sense. The former, which can be traced back to the classical liberal philosophy of Bentham and Mill, is the absence of obstacles and barriers that would prevent individuals from realizing their various goals and aspirations. Here, promoting liberty is primarily a matter of removing, or at least minimizing, the constraints on what a person is allowed to do. Positive liberty on the other hand, is a broader sense of the term, and arises from a view of the individual as having a potential that requires active assistance in order to be realized. Fostering positive liberty entails providing individuals with the goods and services that they would require in order to achieve their aspirations.

Since the Second World War, there has been a fierce ongoing debate about the proper role of institutions, both public and private, for furthering these different senses of freedom. In large part the debate has been centered on questions of negative liberty especially with regard to the following topics: recreational drugs, abortion, guns, gambling and pornography. These issues have divided people into those who believe that the government should remove its restraints with regard to one of these issues and those who feel that, at least with regard to this particular subject, the government must impose some restriction on individual behavior in order to promote the public good.

There has been a general trend towards increasing individual liberty with regard to these topics, but this has not been constant. For example, while many drug laws were liberalized in the 1970s, there was a backlash against this in the 1980s and 1990s with a large increase in federal and state penalties for drug-related activities.

The debate about positive liberty has been less prominent, but it regularly crops up.

With regard to this the most significant period is clearly Lyndon Johnson’s “Great Society” (1963–7). This was the largest attempt, since Roosevelt’s New Deal, to create an active role for the state. The goal was to provide its citizens with freedom from sickness, poverty hunger and ignorance so that they might achieve their greatest potential.

Medicare, Medicaid, Head Start, public broadcasting, food stamps and many other programs were either instituted or initiated during this period. Much of the political and social momentum since then has been against this approach, although the prominence of the debate over nationalizing healthcare in the 1990s demonstrated that the issues are far from settled.

While the distinction between negative and positive liberty is useful, it can also be misleading as it may imply a sharp division between the two. However, what began as a struggle to achieve a greater level of negative freedom may later turn into a battle for more extensive positive freedom. For example, perhaps the most important struggle for freedom in the postwar United States was the civil-rights crusade. In the 1950s and 1960s, it was initially concerned with removing the institutional barriers that had restricted minorities from voting and had radically constrained where they could live, eat, work, or attend school. Eventually many of these obstacles against African Americans were eliminated through Supreme Court decisions, like Brown v. Board of Education, and federal legislation such as the Civil Rights Act of 1964 and the Voting Act of 1965.

As these barriers were removed, however, there were others who felt that their removal alone would not be adequate in promoting genuine freedom for African Americans. They argued for a more activist role for institutions through such programs as affirmative action and economic opportunity zones in poorer neighborhoods.