Medieval Christendom
Among the heirs of Greece and Rome and of Israel were the Christians of varying professions. Perhaps the most dramatic form of censorship in Christendom was that displayed in the development by the Roman Catholic Church of the Index Librorum Prohibitorum, a list of proscribed books, the origins of which go back (in a primitive form) to the 5th century ce and which continued to have official sanction well into the 20th century. The most spectacular instance of the silencing of a thinker of note may well have been the restrictions placed upon Galileo in 1633.
The orthodoxy protected by an institution such as the Index probably had to be a system of thought in which much was made of certain books, particularly if other publications should seem to challenge in significant respects the teachings of the canonical texts. This must have appeared even more acute a problem when means became available, especially after the invention of printing, to produce and distribute books in large quantities.
The establishment of a fairly precise orthodoxy led to a perhaps unprecedented recourse to creeds. Thus, for example, the Nicene Creed was promulgated in 325 ce. It was devised to fend off a heretical threat to Christian doctrine—and it led, partly because of a unilateral change in wording made by the Western church, to a schism that has continued since 1054 between Eastern Orthodoxy and Roman Catholicism.
Thus, it very much mattered which doctrines people were taught and what came to be believed—and this was largely determined, as it usually is, by the action of some authority, ecclesiastical or temporal. Similar developments can be seen in the Islamic world to this day.
It is difficult to distinguish religious and nonreligious elements in some of the more celebrated controversies of the medieval Christian world, just as it is today among Islamic peoples. The persecutions of witches—which ranged across much of Europe from the 14th to the 18th century and cost hundreds of thousands, if not millions, of lives—can be understood as due to various political, social, and psychic disturbances as well as to strictly religious differences.
The trials of Joan of Arc in France (1431) and of Thomas More in England (1535) are notorious illustrations of the difficulty in distinguishing religious from political differences. Indeed, it has been common, because of the experiences of the Middle Ages and of the Renaissance, to see the cause of political liberty as intimately related to the cause of religious liberty (and especially the liberty to do without religion).
The Enlightenment, beginning in the 17th century, attempted to purge Europe of the censorship that found political despotism allied with religious traditionalism. Alexis de Tocqueville was astonished to find in the United States, in the 1830s, that it was possible for ordinary men who stood for political freedom to be, and to remain, religiously devout. This was not the typical combination in the Europe of his day.
Even so, it should be recognized that the rigorous medieval theological-political regime against which Moderns have rebelled did have at its core a principle that subjected the exercise of will (or sovereignty) to the test of wisdom. This principle, upon which the contemporary dedication to freedom of speech may ultimately depend, is reflected in Thomas Aquinas’s insistence in De veritate, “To say that justice depends simply upon the will is to say that the divine will does not proceed according to the order of wisdom, and that is blasphemous.”