Having earned a doctorate, you may pursue a career as an independent researcher in academia, business, government, etc., with the ultimate goal of making meaningful contributions to society. In fact, the purpose of higher education should be to improve oneself and the world via applying one’s newly gained knowledge, not just to add more accolades to one’s CV for self-validation or social status.
Once you’ve reached this point, you have two options. The first is to pursue deep applications based on the subject’s doctrine to advance to higher levels, as did former Indian President Mr. APJ Abdul Kalam. The second is to pursue the same university degree but as a specialist in a different topic or subject if possible.
Additionally, you can go for a post-doctoral degree. Post-doctoral research adds an average of two to three years to the time required to complete a dissertation. Once they graduate, they generally find work in academics, while jobs in the industry are also possible. Unless you have an MD/Ph.D., which is superior to a regular Ph.D. because of its clinical opportunities, you will need to do a post-doc.
To be competitive for a teaching job after earning a Ph.D., candidates must complete one, two, or even three post-doc. A post-doc is required to become a Ph.D. adviser and apply for full professor (or similar) posts in academia in certain countries, such as France or Germany. In many cases, a Ph.D. alone is insufficient; further training is needed, often in the form of a degree known as “habilitation” or its many variations. The habilitation process in France typically takes one year and serves as a “Mini-PhD” thesis.
In “habilitation,” you must describe your study in a document that includes reviewers, a defense before a jury made up solely of full professors or their equivalent, and highlights your vision, management, and supervision abilities. Consider habilitation the equivalent of a secret level in a video game where the Ph.D. defense is the ultimate boss. You may still supervise a Ph.D. student even if you lack habilitation; you’ll have to do it in conjunction with an established scholar. It’s OK as long as there’s at least one rehabilitated supervisory team member. You may get the necessary experience in supervision this way, and subsequently, take your habilitation.
Having more than one degree paves the way for permanent posts like those of tenure-track assistant professors and junior research associates. These are entry-level posts designed for talented young researchers who don’t yet have the necessary expertise to serve as supervisors or in managerial capacities. The hope is that those with experience in supervisory and managerial roles can use that background to advance to the level of full professor or senior research scientist.
In short, after completing your doctoral degree, it’s not compulsory but necessary to do a Post-Doc degree if you want a supervisory role at any prestigious institute.