The PhD began as a German stand-in for the humble Master of Arts
Medieval doctorates required no original research at all, only long residence and exams. The research PhD was a 19th-century Prussian innovation: Berlin's philosophy faculty started demanding a dissertation for what was essentially its MA. Americans flocked over to earn one, and Yale brought the idea home in 1861.
'Philosophy' in the title has nothing to do with the discipline of philosophy. It keeps the Greek sense of love of wisdom, because across most of Europe every field outside theology, law and medicine, from mathematics to history to natural science, fell under the faculty of philosophy. The first doctorate on record was awarded at the University of Paris around 1150, but for centuries higher degrees rewarded advanced learning rather than new discoveries, and most students left without even becoming Masters of Arts.
The turning point was the University of Berlin, founded in 1810 under Prussian control. Its philosophy faculty had absorbed everything now called the sciences and humanities, and professors there concentrated on research, so they asked candidates to prove they could contribute some. The model proved so successful that American graduates crossed the Atlantic for German doctorates. Yale began granting PhDs in 1861 to students who completed graduate coursework and defended a dissertation of original research. Germany itself later split the title, giving scientists a Dr. rer. nat., while the English-speaking world kept 'Doctor of Philosophy' for research doctorates in every field.
Britain was slow. The University of London's DSc of 1860 was an advanced course, not a research degree; Durham introduced the first modern higher doctorate in 1882. Such degrees were extremely senior: the geophysicist Harold Jeffreys likened winning a Cambridge ScD to being nominated for the Royal Society. The PhD as research training arrived in 1917 and quickly attracted British and foreign students alike.
Elsewhere the degree spread unevenly, reaching Russia in 1819 and Italy only in the 1980s. Today candidates typically submit work fit for a peer-reviewed journal and often defend it before examiners; those who have finished coursework but not the thesis are nicknamed 'ABD', all but dissertation. Convention says holders should use either the title Dr or the letters PhD, not both, though that rule is loosening.
Source: Doctor of Philosophy
