Agnosticism is the belief that man cannot be certain of the nature or existence of God, the existence of life after death, or the origin of the universe. Agnosticism is often coupled with empiricism, the view that knowledge can come only from experiences gained through the senses. To agnostics anything that cannot be perceived by the senses cannot be proved and is therefore unknowable. Unlike atheists, who deny the existence of God, agnostics hold that one cannot be sure of God's existence.
The term "agnostic" was coined in 1869 by the British scientist Thomas H. Huxley. Some of the world's outstanding philosophers have been agnostics. Among them are Immanuel Kant, Auguste Comte, Herbert Spencer, and David Hume. Famous American agnostics include William James and George Santayana.