The degree of doctor of philosophy (Ph.D., or sometimes D.Phil.) is awarded by a university or similar body to those who have demonstrated competence in research within a specified academic discipline. A doctorate is a 'higher' degree, and traditionally the third tier of higher education (i.e., Bachelor's degree, Master's degree, Doctorate).
The Ph.D. is usually awarded after the evaluation of a research thesis reporting a substantive research project, or reporting a number of small related studies. It is expected that the work submitted is of 'publishable' standard, that is suitable for publication in a respected research journal. (In some countries the candidate is expected to demonstrate the publishable standard of the work, by having some of it published before the work is assessed for the degree.)
The doctoral candidate is usually examined viva voce (orally) by a panel of examiners who have read the thesis – being questioned about the work and the field within which it is located. In some national contexts the viva is a critical part of the examination process and is conduced in private, but in some contexts the oral examination only takes place after the examiners have decided to pass the submitted thesis, and is open to anyone who wishes to attend, and acts as a public celebration of the completion of the degree.
Commonly, the Ph.D. candidate must be registered as research student for several years, and initially follows a programme of research training and is provided with thesis supervision, but is expected to demonstrate the potential to operate as an independent researcher by the end of the process.
Sometimes a university will accept, from someone who has not been registered as a student, a portfolio of previously published research papers accompanied by a commentary as a submission for examination for the degree of Ph.D. This route is seen as suitable for an experienced independent researcher who does not need research training and supervision.
Although the title of the degree includes the term 'philosophy' this is understood in a broad sense of a contribution to public knowledge and Ph.D. degrees are awarded in all academic disciplines, not just philosophy. The holder of a Ph.D. is entitled to use the title Dr (doctor).
