It is impossible to know with certainty what another person is thinking, making suppression difficult. The concept is developed throughout the Bible, most fully in the writings of
Saul of Tarsus (e.g., "For why should my freedom [
eleutheria] be judged by another's conscience [
suneideseos]?"
1 Corinthians 10:29). in
Rome Although Greek philosophers
Plato and
Socrates had discussed freedom of thought minimally, the edicts of King
Ashoka (3rd century BC) have been called the first decree respecting freedom of conscience. In European tradition, aside from the decree of religious toleration by
Constantine I at Milan in 313, the philosophers
Themistius,
Michel de Montaigne,
Baruch Spinoza,
John Locke,
Voltaire,
Alexandre Vinet, and
John Stuart Mill and the theologians
Roger Williams and
Samuel Rutherford have been considered major proponents of the idea of freedom of conscience (or "soul liberty" in the words of Williams).
Queen Elizabeth I revoked a thought censorship law in the late sixteenth century, because, according to Sir
Francis Bacon, she did "not [like] to make windows into men's souls and secret thoughts". During her reign, however, a number of books published by theorist
Giordano Bruno spurred controversy, mentioning topics banned by the Catholic Church such as the possibility of an infinite universe. Unwilling to recant these ideas, Bruno was eventually
burned as a
heretic in Rome by the
Italian Inquisition, in turn becoming a martyr for free thought.
Oliver Cromwell is described by
Ignaz von Döllinger as "the first among the mighty men of the world to set up one special religious principle, and to enforce it so far as in him lay: ... The principle of liberty of conscience and the repudiation of religious coercion". However,
freedom of expression can be limited through
censorship, arrests,
book burning, or
propaganda, and this tends to discourage freedom of thought. Examples of effective campaigns against freedom of expression are the Soviet suppression of genetics research in favor of a theory known as
Lysenkoism, the book-burning campaigns of
Nazi Germany, the radical
anti-intellectualism enforced in Cambodia under
Pol Pot and in Nazi Germany under
Adolf Hitler, the strict limits on freedom of expression imposed by the
Communist governments of the People's Republic of China and Cuba or by
Capitalist dictatorships such as those of
Augusto Pinochet in Chile and
Francisco Franco in Spain. The
Sapir–Whorf hypothesis, which states that
thought can be embedded in
language, would support the claim that an effort to limit the use of words of language is actually a form of restricting freedom of thought. This was explored in
George Orwell's novel
1984, with the idea of
Newspeak, a stripped-down form of the
English language alleged to lack the capacity for metaphor and limiting expression of original ideas. More recently,
neuroimaging technology has raised concerns about entities possibly reading and subsequently suppressing thought. These concerns form the emerging fields of
neuroethics and
neuroprivacy.
Humanists International publishes the annual
Freedom of Thought Report, which compiles country-by-country material on the treatment of non-religious people and related freedoms of expression and belief. ==See also==