In the times of the Greek democracy, the Roman republic, the American founding, and most of American history, liberty and equality were thought to go together. That changed, says Danielle Allen, author of a book on the Declaration of Independence
First, Karl Marx taught that individual liberty must be sacrificed for the greater goal of social equality. Then, in the Cold War, conservatives and libertarians taught the opposite, that equality must give way to individual liberty. Today, she says, Democrats are stressing the ideals of equality while Republicans are stressing the ideals of liberty. She argues that we need to recapture the sense in which the two go together, as set forth in the Declaration of Independence.