- Pantheism: He defined himself as a pantheist, believing in a God who is not a person, but rather the laws and order of nature.

- Ethical humanism: He believed in the importance of ethical values, such as compassion and justice, and the pursuit of knowledge and understanding.

- Pacifism: He opposed war and violence, and advocated for peaceful resolution of conflicts.

- Civil liberties: He was an outspoken critic of authoritarianism and a defender of civil liberties and individual rights.

- Socialism: He supported socialist ideas, believing that a socialist society would be more equitable and just than a capitalist society.

- Internationalism: He believed in the importance of international cooperation and understanding among nations.

- World government: He advocated for the establishment of a world government to prevent war and promote peace.

- Science and reason: He believed in the power of science and reason to solve problems and advance human knowledge.