1903 in philosophy

Publications

• Konstantin Tsiolkovsky, The Exploration of Cosmic Space by Means of Reaction Devices
• Georg Simmel, The Metropolis and Mental Life
• W. E. B. Du Bois, The Souls of Black Folk
• G. E. Moore, Principia Ethica and ''The Refutation of Idealism''

Births

• February 22 - Frank Ramsey
• May 10 - Hans Jonas
• September 11 - Theodor W. Adorno

Deaths

• October 4 - Otto Weininger
• November 1 - Theodor Mommsen
• December 8 - Herbert Spencer