Liberalism is the conjunction of two ideals. The first is that of individual liberty: liberty of thought, speech, religion, and political action; freedom from government interference with privacy, personal life, and the exercise of individual inclination. The second ideal is that of a democratic society controlled by its citizens and serving their needs, in which inequalities of political and economic power and social position are not excessive. Means of promoting the second ideal include progressive taxation, public provision of a social minimum, and insulation of political affairs from the excessive influence of private wealth. To approach either of these ideals is very difficult. To pursue both of them inevitably results in serious dilemmas. In such cases liberalism tends to give priority to the respect for certain personal rights, even at substantial cost in the realization of other goods such as efficiency, equality, and social stability.
The most formidable challenge to liberalism, both intellectually and politically, is from the left. It is argued that strong safeguards of individual liberty are too great a hindrance to the achievement of economic and social equality, rapid economic progress from underdevelopment, and political stability. A majority of the people in the world are governed on this assumption. Perhaps the most difficult issue is posed by economic power and the political inequality it can create. The criticism from the left is that harmful concentrations of economic power cannot be attacked—or prevented from forming—unless individual actions are more closely restricted than is permitted by the liberal ideal of personal freedom. Radical redistribution is unlikely in a liberal democracy where private wealth controls the political process. A defense against this criticism must either challenge the factual claim or argue that the importance of freedom outweighs these disadvantages.
Liberalism is also under attack from the right. The most conspicuous attacks are not theoretical: the right in its more prominent political manifestations is not particularly attached to individual liberty when that liberty threatens the unequal distribution of wealth and power. But there is also a theoretical challenge from the right, called libertarianism, and while it does not present as serious a moral issue for liberals as does the attack from the left, the two are in some ways symmetrical. Libertarianism, like leftism, fastens on one of the two elements of the liberal ideal and asks why its realization should be inhibited by the demands of the other. Instead of embracing the ideal of equality and the general welfare, libertarianism exalts the claim of individual freedom of action, and asks why state power should be permitted even the interference represented by progressive taxation and public provision of health care, education, and a minimum standard of living.
(Thomas Nagel, “Libertarianism Without Foundations,” review of Anarchy, State, and Utopia, by Robert Nozick, The Yale Law Journal 85 [November 1975]: 136-49, at 136-7)
