PhD and Ph.D are both correct ways to indicate the title, or honorific, of a doctor. However, Ph.D isn’t nearly as common as PhD. In fact, Ph.D is an old-fashioned method of writing it. But, there’s nothing wrong with using it that way. However, it’s more visually correct and recognizable in the modern world as PhD.
So, while there aren’t really any rules to remember for using PhD or Ph.D, it’s important to understand what it means. Plus the history of it will give you a little trivia.
The earliest known documented use of Ph.D is from 1869. It’s an abbreviation of the Latin phrase, “Philosophiae Doctor” or “Doctor of Philosophy.” But “Philosophiae” has roots in ancient Greek, which translates into “love of wisdom.” To call someone a “doctor” is another way to say “learned person.”
Therefore, “Philosophiae Doctor” translates in literal terms to “love of wisdom by a learned person.” This can span a host of arts and sciences including medicine as well as biology, history, literature, sociology, politics, and many more.
The title PhD is the more common version in modern times and it means the same thing. These are people who receive doctorate degrees, which is the highest level of education someone can get. As it was back in 1869, the placement of the honorific can be before or after a name.
Examples of both PhD and Ph.D
The examples below show the myriad of ways in how to use and where to place PhD or Ph.D as an honorific for a person.
Dr. Ken Wellington, PhD
Marybeth Alistair, Ph.D., DDS
Professor Cynthia Kline, PhD
Michael Derringer, Ph.D., MD
You may notice additional acronyms after the use of Ph.D. This is the more common way to use it when you’re listing someone’s name and credentials. It’s frequent to see this in places like convention programs, office boards, or in newspapers. The DDS is Doctor of Dental Surgery and MD is Doctor of Medicine.
In many cases, doctors will have other degrees of study alongside their doctoral education. These additional honorifics indicate that.
Both PhD and Ph.D are correct when referring to the title of a doctor. These are almost always for writing purposes. You would never call a doctor PhD. It’s similar to how you would use Mr., Mrs., or Ms. before someone’s name.