Herbert David Croly (January 23, 1869 – May 17, 1930) was an intellectual leader of the progressive movement as an editor, political philosopher and a co-founder of the magazine The New Republic in early twentieth-century America. His political philosophy influenced many leading progressives including Theodore Roosevelt, as well as his close friends Judge Learned Hand and Supreme Court Justice Felix Frankfurter.His book, The Promise of American Life (1909), looked to the constitutional liberalism as espoused by Alexander Hamilton, combined with the radical democracy of Thomas Jefferson. The book was one of the most influential books in American political history, shaping the ideas of many intellectuals and political leaders. It also influenced the later New Deal. Calling themselves "The New Nationalists", Croly and Walter Weyl sought to remedy the relatively weak national institutions with a strong federal government. He actively promoted a strong army and navy and attacked pacifists who thought democracy at home and peace abroad was best served by keeping America weak.
Croly was one of the founders of modern liberalism in the United States, especially through his books, essays, and a highly influential magazine founded in 1914, The New Republic. In his 1914 book Progressive Democracy, Croly rejected the thesis that the liberal tradition in the United States was inhospitable to anti-capitalist alternatives. He drew from the American past a history of resistance to capitalist wage relations that was fundamentally liberal, and he reclaimed an idea that progressives had allowed to lapse—that working for wages was a lesser form of liberty. Increasingly skeptical of the capacity of social welfare legislation to remedy social ills, Croly argued that America's liberal promise could be redeemed only by syndicalist reforms involving workplace democracy. His liberal goals were part of his commitment to American republicanism.