John Augustine Ryan (1869–1945) was an American Catholic priest who was a noted moral theologian and advocate of social justice.

[9] Ryan saw the social reform debate of the early twentieth century as essentially an argument between libertarian individualists and collectivists concerned with equality, and thus contended that an emphasis on human welfare framed in natural law theory provided the most promising means to combine conflicting concerns over individual and social welfare.

[10] Ryan's influential response was the development of a Catholic critique of the American capitalist system that emphasized the existence of absolute natural human rights.

[11] While Ryan identified himself primarily as a moral theologian, he also made important contributions to American political life and economic thought.

While Ryan later confessed to not fully understanding the book at the time, he cites his first reading of George's work as the beginning of a lifelong commitment to questions of social justice.

Ryan saw his own vocation as the teaching of moral theology and economic justice to the American electorate, emphasizing in particular his influence on Catholic voters and politicians.

Always grounding his political thought in moral theology, Ryan argued that Rerum novarum converted the living wage "from an implicit to an explicit principle of Catholic ethics".

Ryan based his own vision of economic progress in America on equitable wealth distribution, decreased working hours, and a guaranteed minimum wage.

While A Living Wage has achieved a higher degree of recognition, Ryan stated in his autobiography, "Distributive Justice is unquestionably the most important book I have written.

Just as Ryan's economic thought was guided by a commitment to moral theology, his political action was inextricably connected to his religious beliefs.

Though Ryan was primarily an intellectual and moral theologian, his deep conviction that the church had a proper role to play in public affairs led him to maintain a consistent engagement in American politics throughout his lifetime.

Ryan avoided political labels such as liberal or conservative, but eventually settled on "papalist" to describe his public position, meaning "an orthodox commitment to the Holy See.

"[24] Ryan viewed the proper role of the state as the active promotion of the common good only to the extent that it cannot be realized through the family or voluntary associations.

Yet, the text also involved a number of less successful reforms that defy popular interpretations of Ryan as a strictly liberal political thinker, such as a federal ban on the dissemination of information on birth control and rigid support for abortion laws.

He was a noted supporter of the failed Child Labor Amendment to the US Constitution, despite opposition from the influential Archbishop of Boston, Cardinal William Henry O'Connell.

One of Ryan's most controversial ventures into American politics was his national radio endorsement of Democratic Party candidate Franklin D. Roosevelt when he ran for re-election as president in 1936.