Joseph Priestley, FRS (13 March 1733 (O.S.)

– 6 February 1804) was an 18th-century English theologian, Dissenting clergyman, natural philosopher, chemist, educator, and political theorist who publishes over 150 works.

He is usually credited with the discovery of oxygen, having isolated it in its gaseous state, although Carl Wilhelm Scheele and Antoine Lavoisier also have a claim to the discovery.

During his lifetime, Priestley's considerable scientific reputation rests on his invention of soda water, his writings on electricity, and his discovery of several "airs" (gases), the most famous being what Priestley dubs "dephlogisticated air" (oxygen).

However, Priestley's determination to defend phlogiston theory and to reject what will become the chemical revolution eventually leave him isolated within the scientific community.

Priestley's science is integral to his theology, and he consistently tries to fuse Enlightenment rationalism with Christian theism.

In his metaphysical texts, Priestley attempts to combine theism, materialism, and determinism, a project that has been called "audacious and original".

He believes that a proper understanding of the natural world would promote human progress and eventually bring about the Christian Millennium.

(Tapper, Alan.

"Joseph Priestley".

Dictionary of Literary Biography 252: British Philosophers 1500–1799.

Eds.

Philip B. Dematteis and Peter S. Fosl.

Detroit: Gale Group, 2002.)

Priestley, who strongly believes in the free and open exchange of ideas, advocates toleration and equal rights for religious Dissenters, which also leads him to help found Unitarianism in England.

The controversial nature of Priestley's publications, combined with his outspoken support of the French Revolution, arouses public and governmental suspicion; he is eventually forced to flee, in 1791, first to London, and then to the United States, after a mob burns down his home and church.

He spends the last ten years of his life living in Northumberland County, Pennsylvania.

A scholar and teacher throughout his life, Priestley also makes significant contributions to pedagogy, including the publication of a seminal work on English grammar, books on history, and he prepares some of the most influential early timelines.

These educational writings are some of Priestley's most popular works.

It is his metaphysical works, however, that have the most lasting influence: leading philosophers including Jeremy Bentham, John Stuart Mill, and Herbert Spencer credit them among the primary sources for utilitarianism.