Final answer:
Herbert David Croly was a prominent American political philosopher and journalist who contributed to the Progressive Movement and influenced early 20th-century American liberalism with his book 'The Promise of American Life'.
Step-by-step explanation:
Herbert David Croly was an influential American political philosopher and journalist who lived from 1869 to 1930. He is most well-known for his book The Promise of American Life (1909), where he advocated for a new form of liberalism that influenced the Progressive Movement and the development of modern American liberalism. Croly's ideas significantly impacted the policies of presidents such as Theodore Roosevelt and Woodrow Wilson.
Croly co-founded The New Republic magazine in 1914, which became a significant platform for discussing progressive ideas, shaping public opinion, and advocating for reform in the early 20th century. His work remains relevant today as it addresses the relationship between individual liberty, governmental authority, and social justice.