An encyclical was originally a circular letter sent to all the churches of a particular area in the ancient Roman Church. At that time, the word could be used for a letter sent out by any bishop. The word comes from Late Latin encyclios (from Latin encyclius, a Latinization of Greek enkyklios meaning "circular", "in a circle", or "all-round", also part of the origin of the word encyclopedia).
Although the term "encyclical" originally simply meant a circulating letter, it acquired a more specific meaning within the context of the Catholic Church. In 1740, Pope Benedict XIV wrote a letter titled Ubi primum, which is generally regarded as the first encyclical in a modern sense. The term is now used almost exclusively for a kind of letter sent out by the Pope.
For the modern Roman Catholic Church, a papal encyclical is a specific category of papal document, a kind of pastoral letter concerning Catholic doctrine, sent by the Pope and usually addressed especially to patriarchs, primates, archbishops and bishops who are in communion with the Holy See. The form of the address can vary widely, and may concern bishops in a particular area, or designate a wider audience. Papal encyclicals usually take the form of a papal brief due to their more personal nature as opposed to the formal papal bull. They are usually written in Latin and, like all papal documents, the title of the encyclical is usually taken from its first few words (its incipit).
Within Catholicism in recent times, an encyclical is generally used for significant issues and is second in importance only to the highest ranking document now issued by popes, an Apostolic Constitution. However, the designation "encyclical" does not always denote such a degree of significance. The archives at the Vatican website currently classify certain early encyclicals as Apostolic Exhortations, a term generally applied to a type of document with a broader audience than the bishops alone.
Pope Pius XII held that papal encyclicals, even when they are not of ordinary magisterium, can nonetheless be sufficiently authoritative to end theological debate on a particular question:
It is not to be thought that what is set down in Encyclical letters does not demand assent in itself, because in this the popes do not exercise the supreme power of their magisterium. For these matters are taught by the ordinary magisterium, regarding which the following is pertinent: "He who heareth you, heareth Me." (Luke 10:16); and usually what is set forth and inculcated in Encyclical Letters, already pertains to Catholic doctrine. But if the Supreme Pontiffs in their acts, after due consideration, express an opinion on a hitherto controversial matter, it is clear to all that this matter, according to the mind and will of the same Pontiffs, cannot any longer be considered a question of free discussion among theologians.
Encyclicals indicate high papal priority for an issue at a given time. Pontiffs define when, and under which circumstances, encyclicals should be issued. They may choose to issue an apostolic constitution, bull, encyclical, apostolic letter or give a papal speech. Popes have differed on the use of encyclicals: on the issue of birth control and contraception, Pope Pius XI issued the encyclical Casti connubii, while Pope Pius XII gave a speech to midwives and the medical profession, clarifying the position of the church on the issue. Pope Paul VI published an encyclical Humanae vitae on the same topic. On matters of war and peace, Pope Pius XII issued ten encyclicals, mostly after 1945, three of them protesting the Soviet invasion of Hungary in order to crack down on the Hungarian Revolution in 1956: Datis nuperrime, Sertum laetitiae and Luctuosissimi eventus. Pope Paul VI spoke about the war in Vietnam and Pope John Paul II, issued a protest against the war in Iraq using the medium of speeches. On social issues, Pope Leo XIII promulgated Rerum novarum (1891), which was followed by Quadragesimo anno (1931) of Pius XI and Centesimus annus (1991) of John Paul II. Pius XII spoke on the same topic to a consistory of cardinals, in his Christmas messages and to numerous academic and professional associations.
|Portrait||Pope||Term of papacy||Number and Ratio||Texts|
|Pope Benedict XIV||1740-1758||48 Encyclicals|||
|Pope Clement XIII||1758-1769||6 Encyclicals|
|Pope Clement XIV||1769-1774||2 Encyclicals|
|Pope Pius VI||1775-1799||27 Encyclicals|||
|Pope Pius VII||1800-1823||4 Encyclicals|
|Pope Leo XII||1823-1829||2 Encyclicals|
|Pope Pius VIII||1829-1830||1 Encyclical|
|Pope Gregory XVI||1831-1846||9 Encyclicals|||
|Pope Pius IX||1846-1878||38 Encyclicals|||
|Pope Leo XIII||1878-1903||86 Encyclicals|||
|Pope Pius X||1903-1914||17 Encyclicals|||
|Pope Benedict XV||1914-1922||12 Encyclicals|||
|Pope Pius XI||1922-1939||31 Encyclicals|||
|Pope Pius XII||1939-1958||41 Encyclicals|||
|Pope John XXIII||1958-1963||8 Encyclicals|
|Pope Paul VI||1963-1978||7 Encyclicals|
|Pope John Paul I||1978-1978||0 Encyclicals|
|Pope John Paul II||1978-2005||14 Encyclicals||
|Pope Benedict XVI||2005-2013||3 Encyclicals|
|Pope Francis||2013-present||3 Encyclicals|