The doctorate appeared in medieval Europe as a license to teach at a medieval university. Its roots can be traced to the early church when the term "doctor" referred to the Apostles, church fathers and other Christian authorities who taught and interpreted the Bible. The right to grant a licentia docendi was originally reserved to the church which required the applicant to pass a test, to take oath of allegiance and pay a fee. The Third Council of the Lateran of 1179 guaranteed the access – now largely free of charge – of all able applicants, who were, however, still tested for aptitude by the ecclesiastic scholastic. This right remained a bone of contention between the church authorities and the slowly emancipating universities, but was granted by the pope to the University of Paris in 1213 where it became a universal license to teach (licentia ubiquie docendi). However, while the licentia continued to hold a higher prestige than the bachelor's degree (Baccalaureus), it was ultimately reduced to an intermediate step to the Magister and doctorate, both of which now became the exclusive qualification for teaching.
At the university, doctoral training was a form of apprenticeship to a guild. The traditional term of study before new teachers were admitted to the guild of "Masters of Arts," seven years, was the same as the term of apprenticeship for other occupations. Originally the terms "master" and "doctor" were synonymous, but over time the doctorate came to be regarded as a higher qualification than the master's degree. A hypothesis by George Makdisi that the doctorate has its origins in the Islamic Ijazah, a 180 degree turnaround to an earlier view of him which helds that both system were of "the most fundamental difference," has been rejected by Tony Huff as unsubstantiated.
The usage and meaning of the doctorate has changed over time, and it has also been subject to regional variations. For instance, until the early 20th century few academic staff or professors in English-speaking universities held doctorates, except for very senior scholars and those in holy orders. After that time the German practice of requiring prospective lecturers to have completed a "research doctorate" became widespread. Additionally, universities' shifts to "research oriented" education increased the importance of the doctorate. Today such a doctorate is generally a prerequisite for pursuing an academic career, although not everyone who receives a research doctorate becomes an academic by profession. Many universities also award "honorary doctorates" to individuals who have been deemed worthy of special recognition, either for scholarly work or for other contributions to the university or to society.
Although the research doctorate is almost universally accepted as the standard qualification for an academic career, it is a relatively new invention.
The older-style doctorates (now usually called "Higher Doctorates" in the United Kingdom) take much longer to complete, since candidates must show themselves to be leading experts in their subjects. These doctorates are now less common in some countries, and are often awarded honoris causa. The habilitation is still used for academic recruitment purposes in many countries within the EU and involves either a new long thesis (a second book) or a portfolio of research publications. The habilitation demonstrates independent and thorough research, experience in teaching and lecturing and, more recently, the ability to generate funding within the area of research. The "habilitation" is regarded as a senior post-doctoral qualification, many years after the research doctorate, and can be necessary for a Privatdozent (in Germany) or professor position.
A similar system traditionally holds in Russia. Already in the Russian Empire the academic degree doctor of science (doktor nauk) marked the highest academic degree which can be achieved by an examination. This system was generally adopted by the USSR/Russia and many post-Soviet countries.