Pyotr or Petr Yakovlevich Chaadaev, also spelled Jakovlevic Caadaev, or Tschaadajew was born in Moscow. After leaving Moscow University without completing his course in 1812, Chaadaev entered the army and served in the Napoleonic Wars.

Friend with Alexander Pushkin, Chaadaev is the author of the Philosophical Letters. His work could not be published in Russia because of its highly critical nature of Russia's significance in world history and politics. When in 1836 the first (and only one published volume during his life) was published in the Russian magazine Telescope, its editor was exiled to the Far North of Russia.

Most of his works have been edited by his biographer, M. Gershenzon (two volumes, Moscow, 1913-14), whose excellent little study of the philosopher was published at St. Petersburg in 1908.