A Doctor of Philosophy (PhD or DPhil; Latin: philosophiae doctor or doctor in philosophia)[1] is a terminal degree, that usually denotes the highest level of academic achievement in a given discipline and is awarded following a course of graduate study and original research. The name of the degree is most often abbreviated PhD (or, at times, as Ph.D. in North America), pronounced as three separate letters (/ˌpiːeɪtʃˈdiː/ PEE-aych-DEE).[2][3][4]
The abbreviation DPhil, for "Doctor of Philosophy",[5] is used by the University of Oxford.[6] Additionally, it was formerly used by the University of York and University of Sussex in the United Kingdom.[7]
PhDs are awarded for programs across the whole breadth of academic fields. Since it is an earned research degree, those studying for a PhD are required to produce original research that expands the boundaries of knowledge, normally in the form of a dissertation, and, in some cases, defend their work before a panel of other experts in the field. In many fields, the completion of a PhD is typically required for employment as a university professor, researcher, or scientist.[8]
In the context of the Doctor of Philosophy and other similarly titled degrees, the term "philosophy" does not refer to the field or academic discipline of philosophy, but is used in a broader sense in accordance with its original Greek meaning, which is "love of wisdom". In most of Europe, all fields (history, philosophy, social sciences, mathematics, and natural philosophy/sciences)[9] other than theology, law, and medicine (the so-called professional, vocational, or technical curricula) were traditionally known as philosophy, and in Germany and elsewhere in Europe the basic faculty of liberal arts was known as the "faculty of philosophy".[citation needed]
A PhD candidate must submit a project, thesis, or dissertation often consisting of a body of original academic research, which is in principle worthy of publication in a peer-reviewed journal.[10] In many countries, a candidate must defend this work before a panel of expert examiners appointed by the university. Universities sometimes award other types of doctorate besides the PhD, such as the Doctor of Musical Arts (D.M.A.) for music performers, Doctor of Juridical Science (S.J.D.) for legal scholars and the Doctor of Education (Ed.D.) for studies in education. In 2005 the European University Association defined the "Salzburg Principles", 10 basic principles for third-cycle degrees (doctorates) within the Bologna Process.[11] These were followed in 2016 by the "Florence Principles", seven basic principles for doctorates in the arts laid out by the European League of Institutes of the Arts, which have been endorsed by the European Association of Conservatoires, the International Association of Film and Television Schools, the International Association of Universities and Colleges of Art, Design and Media, and the Society for Artistic Research.[12]
The specific requirements to earn a PhD degree vary considerably according to the country, institution, and time period, from entry-level research degrees to higher doctorates. During the studies that lead to the degree, the student is called a doctoral student or PhD student; a student who has completed any necessary coursework and related examinations and is working on their thesis/dissertation is sometimes known as a doctoral candidate or PhD candidate. A student attaining this level may be granted a Candidate of Philosophy degree at some institutions or may be granted a master's degree en route to the doctoral degree. Sometimes this status is also colloquially known as "ABD", meaning "all but dissertation".[13] PhD graduates may undertake a postdoc in the process of transitioning from study to academic tenure.[citation needed]
Individuals who have earned the Doctor of Philosophy degree use the title Doctor (often abbreviated "Dr" or "Dr."), although the etiquette associated with this usage may be subject to the professional ethics of the particular scholarly field, culture, or society. Those who teach at universities or work in academic, educational, or research fields are usually addressed by this title "professionally and socially in a salutation or conversation".[14] Alternatively, holders may use post-nominal letters such as "Ph.D.", "PhD", or "DPhil", depending on the awarding institution. It is, however, traditionally considered incorrect to use both the title and post-nominals together, although usage in that regard has been evolving over time.[15]
In the universities of Medieval Europe, study was organized in four faculties: the basic faculty of arts, and the three higher faculties of theology, medicine, and law (canon law and civil law). All of these faculties awarded intermediate degrees (bachelor of arts, of theology, of laws, of medicine) and final degrees. Initially, the titles of master and doctor were used interchangeably for the final degrees—the title Doctor was merely a formality bestowed on a Teacher/Master of the art—but by the late Middle Ages the terms Master of Arts and Doctor of Theology/Divinity, Doctor of Law, and Doctor of Medicine had become standard in most places (though in the German and Italian universities the term Doctor was used for all faculties).[16]
The doctorates in the higher faculties were quite different from the current PhD degree in that they were awarded for advanced scholarship, not original research. No dissertation or original work was required, only lengthy residency requirements and examinations. Besides these degrees, there was the licentiate. Originally this was a license to teach, awarded shortly before the award of the master's or doctoral degree by the diocese in which the university was located, but later it evolved into an academic degree in its own right, in particular in the continental universities.
According to Keith Allan Noble (1994), the first doctoral degree was awarded in medieval Paris around 1150.[17] The doctorate of philosophy developed in Germany as the terminal teacher's credential in the 17th century (circa 1652).[18] There were no PhDs in Germany before the 1650s (when they gradually started replacing the MA as the highest academic degree; arguably, one of the earliest German PhD holders is Erhard Weigel (Dr. phil. hab., Leipzig, 1652).[citation needed]
The full course of studies might, for example, lead in succession to the degrees of Bachelor of Arts, Licentiate of Arts, Master of Arts, or Bachelor of Medicine, Licentiate of Medicine, or Doctor of Medicine, but before the early modern era, many exceptions to this existed. Most students left the university without becoming masters of arts, whereas regulars (members of monastic orders) could skip the arts faculty entirely.[19][20][21]
This situation changed in the early 19th century through the educational reforms in Germany, most strongly embodied in the model of the University of Berlin, founded in 1810 and controlled by the Prussian government. The arts faculty, which in Germany was labelled the faculty of philosophy, started demanding contributions to research,[22] attested by a dissertation, for the award of their final degree, which was labelled Doctor of Philosophy (abbreviated as Ph.D.)—originally this was just the German equivalent of the Master of Arts degree. Whereas in the Middle Ages the arts faculty had a set curriculum, based upon the trivium and the quadrivium, by the 19th century it had come to house all the courses of study in subjects now commonly referred to as sciences and humanities.[23] Professors across the humanities and sciences focused on their advanced research.[24] Practically all the funding came from the central government, and it could be cut off if the professor was politically unacceptable.[relevant?][25]
These reforms proved extremely successful, and fairly quickly the German universities started attracting foreign students, notably from the United States. The American students would go to Germany to obtain a PhD after having studied for a bachelor's degree at an American college. So influential was this practice that it was imported to the United States, where in 1861 Yale University started granting the PhD degree to younger students who, after having obtained the bachelor's degree, had completed a prescribed course of graduate study and successfully defended a thesis or dissertation containing original research in science or in the humanities.[26] In Germany, the name of the doctorate was adapted after the philosophy faculty started being split up − e.g. Dr. rer. nat. for doctorates in the faculty of natural sciences − but in most of the English-speaking world the name "Doctor of Philosophy" was retained for research doctorates in all disciplines.
The PhD degree and similar awards spread across Europe in the 19th and early 20th centuries. The degree was introduced in France in 1808, replacing diplomas as the highest academic degree; into Russia in 1819, when the Doktor Nauk degree, roughly equivalent to a PhD, gradually started replacing the specialist diploma, roughly equivalent to the MA, as the highest academic degree; and in Italy in 1927, when PhDs gradually started replacing the Laurea as the highest academic degree.[citation needed]
Research degrees first appeared in the UK in the late 19th century in the shape of the Doctor of Science (DSc or ScD) and other such "higher doctorates". The University of London introduced the DSc in 1860, but as an advanced study course, following on directly from the BSc, rather than a research degree. The first higher doctorate in the modern sense was Durham University's DSc, introduced in 1882.[27]
This was soon followed by other universities, including the University of Cambridge establishing its ScD in the same year and the University of London transforming its DSc into a research degree in 1885. These were, however, very advanced degrees, rather than research-training degrees at the PhD level. Harold Jeffreys said that getting a Cambridge ScD was "more or less equivalent to being proposed for the Royal Society."[28]
In 1917, the current PhD degree was introduced, along the lines of the American and German model, and quickly became popular with both British and foreign students.[29] The slightly older degrees of Doctor of Science and Doctor of Literature/Letters still exist at British universities; together with the much older degrees of Doctor of Divinity (DD), Doctor of Music (DMus), Doctor of Civil Law (DCL), and Doctor of Medicine (MD), they form the higher doctorates, but apart from honorary degrees, they are only infrequently awarded.
In English (but not Scottish) universities, the Faculty of Arts had become dominant by the early 19th century. Indeed, the higher faculties had largely atrophied, since medical training had shifted to teaching hospitals,[30] the legal training for the common law system was provided by the Inns of Court (with some minor exceptions, see Doctors' Commons), and few students undertook formal study in theology. This contrasted with the situation in the continental European universities at the time, where the preparatory role of the Faculty of Philosophy or Arts was to a great extent taken over by secondary education: in modern France, the Baccalauréat is the examination taken at the end of secondary studies. The reforms at the Humboldt University transformed the Faculty of Philosophy or Arts (and its more recent successors such as the Faculty of Sciences) from a lower faculty into one on a par with the Faculties of Law and Medicine.
Similar developments occurred in many other continental European universities, and at least until reforms in the early 21st century, many European countries (e.g., Belgium, Spain, and the Scandinavian countries) had in all faculties triple degree structures of bachelor (or candidate) − licentiate − doctor as opposed to bachelor − master − doctor; the meaning of the different degrees varied from country to country, however. To this day, this is also still the case for the pontifical degrees in theology and canon law; for instance, in sacred theology, the degrees are Bachelor of Sacred Theology (STB), Licentiate of Sacred Theology (STL), and Doctor of Sacred Theology (STD), and in canon law: Bachelor of Canon Law (JCB), Licentiate of Canon Law (JCL), and Doctor of Canon Law (JCD).
Until the mid-19th century, advanced degrees were not a criterion for professorships at most colleges. That began to change as the more ambitious scholars at major schools went to Germany for one to three years to obtain a PhD in the sciences or humanities.[31][32] Graduate schools slowly emerged in the United States. In 1852, the first honorary PhD in the nation was given at Bucknell University in Lewisburg, Pennsylvania to Ebenezer Newton Elliott.[33] Nine years later, in 1861, Yale University awarded three PhDs: to Eugene Schuyler in philosophy and psychology, Arthur Williams Wright in physics, and James Morris Whiton in classics.[34][35]
Over the following two decades, Harvard University, New York University, Princeton University, and the University of Pennsylvania, also began granting the degree. Major shifts toward graduate education were foretold by the opening of Clark University in 1887 which offered only graduate programs and the Johns Hopkins University which focused on its PhD program. By the 1890s, Harvard, Columbia, Michigan and Wisconsin were building major graduate programs, whose alumni were hired by new research universities. By 1900, 300 PhDs were awarded annually, most of them by six universities. It was no longer necessary to study in Germany.[36][37] However, half of the institutions awarding earned PhDs in 1899 were undergraduate institutions that granted the degree for work done away from campus.[33] Degrees awarded by universities without legitimate PhD programs accounted for about a third of the 382 doctorates recorded by the US Department of Education in 1900, of which another 8–10% were honorary.[38] The awarding of PhD as an honorary degree was banned by the Board of Regents of the University of the State of New York in 1897. This had a nation-wide impact, and after 1907, less than 10 honorary PhDs were awarded in the United States each year.[39] The last authenticated PhD awarded honoris causa was awarded in 1937 to Bing Crosby by Gonzaga University.[39]
At the start of the 20th century, U.S. universities were held in low regard internationally and many American students were still traveling to Europe for PhDs. The lack of centralised authority meant anyone could start a university and award PhDs. This led to the formation of the Association of American Universities by 14 leading research universities (producing nearly 90% of the approximately 250 legitimate research doctorates awarded in 1900), with one of the main goals being to "raise the opinion entertained abroad of our own Doctor's Degree."[38]
In Germany, the national government funded the universities and the research programs of the leading professors. It was impossible for professors who were not approved by Berlin to train graduate students. In the United States, by contrast, private universities and state universities alike were independent of the federal government. Independence was high, but funding was low. The breakthrough came from private foundations, which began regularly supporting research in science and history; large corporations sometimes supported engineering programs. The postdoctoral fellowship was established by the Rockefeller Foundation in 1919. Meanwhile, the leading universities, in cooperation with the learned societies, set up a network of scholarly journals. "Publish or perish" became the formula for faculty advancement in the research universities. After World War II, state universities across the country expanded greatly in undergraduate enrollment, and eagerly added research programs leading to masters or doctorate degrees. Their graduate faculties had to have a suitable record of publication and research grants. Late in the 20th century, "publish or perish" became increasingly important in colleges and smaller universities.[40]
Detailed requirements for the award of a PhD degree vary throughout the world and even from school to school. It is usually required for the student to hold an Honours degree or a Master's degree with high academic standing, in order to be considered for a PhD program.[citation needed] In the US, Canada, India, and Denmark, for example, many universities require coursework in addition to research for PhD degrees. In other countries (such as the UK) there is generally no such condition, though this varies by university and field.[41] Some individual universities or departments specify additional requirements for students not already in possession of a bachelor's degree or equivalent or higher. In order to submit a successful PhD admission application, copies of academic transcripts, letters of recommendation, a research proposal, and a personal statement are often required. Most universities also invite for a special interview before admission.
A candidate must submit a project, thesis, or dissertation often consisting of a body of original academic research, which is in principle worthy of publication in a peer-reviewed context.[10] Moreover, some PhD programs, especially in science, require one to three published articles in peer-reviewed journals. In many countries, a candidate must defend this work before a panel of expert examiners appointed by the university; this defense is open to the public in some countries, and held in private in others; in other countries, the dissertation is examined by a panel of expert examiners who stipulate whether the dissertation is in principle passable and any issues that need to be addressed before the dissertation can be passed.
Some universities in the non-English-speaking world have begun adopting similar standards to those of the anglophone PhD degree for their research doctorates (see the Bologna process).[42]
A PhD student or candidate is conventionally required to study on campus under close supervision. With the popularity of distance education and e-learning technologies, some universities now accept students enrolled into a distance education part-time mode.
In a "sandwich PhD" program, PhD candidates do not spend their entire study period at the same university. Instead, the PhD candidates spend the first and last periods of the program at their home universities and in between conduct research at another institution or field research.[43] Occasionally a "sandwich PhD" will be awarded by two universities.[44]
A career in academia generally requires a PhD, although in some countries it is possible to reach relatively high positions without a doctorate. In North America, professors are increasingly being required to have a PhD, and the percentage of faculty with a PhD may be used as a university ratings measure.[45]
The motivation may also include increased salary, but in many cases, this is not the result. Research by Bernard H. Casey of the University of Warwick, U.K, suggests that, over all subjects, PhDs provide an earnings premium of 26% over non-accredited graduates, but notes that master's degrees already provide a premium of 23% and a bachelor's 14%. While this is a small return to the individual (or even an overall deficit when tuition and lost earnings during training are accounted for), he claims there are significant benefits to society for the extra research training.[46]However, some research suggests that overqualified workers are often less satisfied and less productive at their jobs.[47] These difficulties are increasingly being felt by graduates of professional degrees, such as law school, looking to find employment. PhD students may need to take on debt to undertake their degree.[48][49]
A PhD is also required in some positions outside academia, such as research jobs in major international agencies. In some cases, the Executive Directors of some types of foundations may be expected to hold a PhD[citation needed]. A PhD is sometimes felt to be a necessary qualification in certain areas of employment, such as in foreign policy think-tanks: U.S. News & World Report wrote in 2013 that "[i]f having a master's degree at the minimum is de rigueur in Washington's foreign policy world, it is no wonder many are starting to feel that the PhD is a necessary escalation, another case of costly signaling to potential employers".[50] Similarly, an article on the Australian public service states that "credentialism in the public service is seeing a dramatic increase in the number of graduate positions going to PhDs and masters degrees becoming the base entry level qualification".[51]
The Economist published an article in 2010 citing various criticisms against the state of PhDs. These included a prediction by economist Richard B. Freeman that, based on pre-2000 data, only 20% of life science PhD students would gain a faculty job in the U.S., and that in Canada 80% of postdoctoral research fellows earned less than or equal to an average construction worker ($38,600 a year). According to the article, only the fastest developing countries (e.g. China or Brazil) have a shortage of PhDs.[47] In 2022, Nature reported that PhD students' wages in biological sciences in the US do not cover living costs.[52]
The U.S. higher education system often offers little incentive to move students through PhD programs quickly and may even provide incentive to slow them down. To counter this problem, the United States introduced the