Research doctorates are programs of advanced study and supervised research. They are mainly comprised of three stages. The first stage is a series of preliminary course, seminar and laboratory studies, which candidates need to pass in order to proceed with doctoral studies. The second part contains advanced seminars during which the student selects a subject for the dissertation and designs his own research. Completing the dissertation, which can take from one to several years, and defending it during a public oral examination, will lead to the doctorate degree, the most common of which is the Doctor of Philosophy (Ph.D.). Apart from this degree are several other research doctorates, equivalent in level, such as Doctor of Industrial Technology (D.I.T.) and Doctor of Education (Ed.D.).
Certain fields of study in the United States, such as law, medicine and psychology, have professional doctorates, where students are not committed mainly in scholarly research, but in a profession. Professional doctorates focus on the holder's competency in practicing the acquired theory. The Juris Doctor (JD) and Doctor of Psychology (Psy.D.) are only two examples of such qualifications. Many are also referred to as 'first professional degrees,' as they are the first degrees students acquire in their fields.
An honorary doctorate, or honoris causa degree, is awarded to individuals for their contribution to a specific field, such as science or arts. Skipping the prerequisites for a degree, such as enrolling in a course and passing examinations, universities award the degree as a means of honoring the recipient's achievements, or even for publicity purposes. The honorary degree does not have the same importance as research and professional doctorates, even though many of its recipients, such as Maya Angelou and the journalist Hunter S. Thompson, insisted on using the title of Doctor after they received their honoris causa degrees.
Doctorate degrees signify the recipients' expertise in a given field and their ability to practice it, either by teaching or in their everyday professions, which demand nothing less than the highest level of knowledge. It would be difficult to think of a doctor or a lawyer, responsible for a man's life or reputation, being hesitant during an operation or at court. In addition, you cannot expect the teachers in higher education institutions to be less than experts on their subject. The most secure way to assess their ability to live up to their expectations is through a doctorate, hence the difficulty in obtaining a doctoral degree (honorary degrees are excluded).