Notes On The PhD Degree
Comer of Purdue University
Last week at the department colloquium coffee hour, several students
engaged the faculty in a discussion about our Ph.D. program. It became clear
that many of the students did not understand the basics; they were surprised
at some of the questions and confused by some of the answers.
These notes provide basic information about the purpose of a Ph.D. program
in an attempt to help students decide whether to pursue a Ph.D. degree.
A Doctor of Philosophy degree, abbreviated Ph.D., is the highest academic
degree anyone can earn. Because earning a Ph.D. requires extended study and
intense intellectual effort, less than one percent of the population attains
the degree. Society shows respect for a person who holds a Ph.D. by
addressing them with the title "Doctor".
To earn a Ph.D., one must accomplish two things. First, one must master
a specific subject completely. Second, one must extend the body of knowledge
about that subject.
Mastering A Subject
To master a subject, a student searches the published literature to find
and read everything that has been written about the subject. In scientific
disciplines, a student begins by studying general reference works such as
text books. Eventually, the student must also search scholarly journals,
the publications that scientists use to exchange information and record
reports of their scientific investigations.
Each university establishes general guidelines that a student must follow
to earn a Ph.D. degree, and each college or department within a university
sets specific standards by which it measures mastery of a subject. Usually,
in preparing for Ph.D. work in a given field, a student must earn both a
Bachelor's and Master's degree (or their equivalent) in that field or in a
closely related field. To demonstrate complete mastery of the subject, a
student may be required to complete additional graduate-level courses,
maintain a high grade average, or take a battery of special examinations.
In many institutions, students must do all three.
Because examinations given as part of a Ph.D. curriculum assess expert
knowledge, they are created and evaluated by a committee of experts, each of
whom holds a Ph.D. degree.
The essence of a Ph.D., the aspect that distinguishes Ph.D. study
from other academic work, can be summarized in a single word: research.
To extend knowledge, one must explore, investigate, and contemplate. The
scientific community uses the term "research" to capture the idea.
In scientific disciplines, research often implies experimentation, but
research is more than mere experiments -- it means interpretation and deep
understanding. For Computer Scientists, research means searching to uncover
the principles that underlie digital computation and communication. A
researcher must discover new techniques that aid in building or using
computational mechanisms. Researchers look for new abstractions, new
approaches, new algorithms, new principles, or new mechanisms.
To complete a Ph.D., each student must present results from their research
to the faculty in a lengthy, formal document called a dissertation (more
popularly referred to as a thesis). The student must then submit their
dissertation to the faculty and defend their work an oral examination.
Relationship To Products
In some cases, the results of scientific research can be used to develop
new products or improve those that exist. However, scientists do not use
commercial success or potential commercial profits as a measure of their work;
they conduct investigations to further human understanding and the body of
knowledge humans have compiled. Often, the commercial benefits of scientific
research are much greater in the long-term than in the short-term.
Computer Science research can include such diverse activities as designing
and building new computer systems, proving mathematical theorems, writing
computer software, measuring the performance of a computer system, using
analytical tools to assess a design, or studying the errors programmers make
as they build a large software system. Because a researcher chooses the
activities appropriate to answer each question that arises in a research
investigation, and because new questions arise as an investigation proceeds,
research activities vary from project to project and over time in a single
project. A researcher must be prepared to use a variety of approaches and
A Few Questions To Ask
Many of you are trying to decide whether to pursue a Ph.D. degree. Here
are a few questions you might ask yourself.
1. Do you want a research career?
Before enrolling in a Ph.D. program, you should carefully consider your
long-term goals. Because earning a Ph.D. is training for research, you should
ask yourself whether a research position is your long-term goal. If it is,
a Ph.D. degree is the standard path to your chosen career (a few people have
managed to obtain a research position without a Ph.D., but they are the
exception, not the rule). If, however, you want a non-research career, a
Ph.D. is definitely not for you.
2. Do you want an academic position?
A Ph.D. is the de facto "union card" for an academic position. Although
it is possible to obtain an academic position without a Ph.D., the chances
are low. Major universities (and most colleges) require each member of their
faculty to hold a Ph.D. and to engage in research activities. Why? To insure
that the faculty have sufficient expertise to teach advanced courses and to
force faculty to remain current in their chosen field.
The U.S. State Department diplomatic protocol ranks the title "professor"
higher than the title "doctor". It does so in recognition of academic
requirements: most professors hold a Ph.D., but not all people who hold a
Ph.D. degree are professors.
3. Do you have what it takes?
It is difficult for an individual to assess their own capabilities.
The following guidelines and questions may be of help.
- In your college and graduate courses, were you closer
to the top of your class or the bottom? How well did
you do on the GRE or other standardized tests?
- Are you prepared to tackle a project larger than
any you have undertaken before? You must commit to
multiple years of hard work. Are you willing to
reduce or forego other activities?
- Research discoveries often arise when one looks at
old facts in a new way. Do you shine when solving
problems? Do you like "brain teasers" and similar
puzzles? Are you good at solving them? In school,
did you find advanced mathematics enjoyable or
- Intense curiosity:
- Have you always been compelled to understand the
world around you and to find out how things work?
A natural curiosity makes research easier. Did you
fulfill minimum requirements or explore further on
- Most students are unprepared for Ph.D. study. They
find it unexpectedly different than course work.
Suddenly thrust into a world in which no one knows
the answers, students sometimes flounder. Can you
adapt to new ways of thinking? Can you tolerate
searching for answers even when no one knows the
- By the time a student finishes an undergraduate
education, they have become accustomed to receiving
grades for each course each semester. In a Ph.D.
program, work is not divided neatly into separate
courses, professors do not partition tasks into little
assignments, and the student does not receive a grade
for each small step. Are you self-motivated enough
to keep working toward a goal without day-to-day
- If you choose to enroll in a Ph.D. program, you will
compete with others at the top. More important,
once you graduate, your peers will include some of
the brightest people in the world. You will be
measured and judged in comparison to them. Are you
willing to compete at the Ph.D. level?
- Compared to coursework, which is carefully planned by
a teacher, Ph.D. study has less structure. You will
have more freedom to set your own goals, determine
your daily schedule, and follow interesting ideas.
Are you prepared to accept the responsibility that
accompanies the additional freedoms? Your success
or failure in Ph.D. research depends on it.
A few warnings:
Students sometimes enroll in a Ph.D. program for the wrong reasons. After
a while, such students find that the requirements overwhelm them. Before
starting one should realize that a Ph.D. is not:
- Prestigious in itself
- Almost everyone who has obtained a Ph.D. is proud of
their efforts and the result. However, you should
understand that once you graduate, you will work among
a group of scientists who each hold a Ph.D. degree.
(One faculty member used to chide arrogant graduate
students by saying, "I don't see why you think it's
such a great accomplishment -- all my friends have a
- A guarantee of respect for all your opinions
- Many students believe that once they earn a Ph.D.
people will automatically respect all their opinions.
You will learn, however, that few people assume a
Ph.D. in one subject automatically makes you an
authority on others. It is especially true in the
science communicaty; respect must be earned.
- A goal in itself
- A Ph.D. degree prepares you for research. If all
you want is a diploma to hang on the wall, there are
much easier ways to obtain one. After you graduate,
you will have occasion to compare your record of
accomplishment to those of other scientists. You
will realize that what counts is the research work
accumulated after a scientist finishes their formal
- A job guarantee
- When an economy slows, everyone can suffer. In fact,
some companies reduce research before they reduce
production, making Ph.D.s especially vulnerable.
Furthermore, once a person earns a Ph.D., many
companies will not hire that person for a non-research
position. As in most professions, continued
employment depends on continued performance.
- A practical way to impress your family or friends
Your mother may be proud and excited when you enroll
in a Ph.D. program. After all, she imagines that she
will soon be able to brag about her child, "the
doctor." However, a desire to impress others is
insufficient motivation for the effort required.
- Something you can "try" to find out how smart you are
- Sorry, but it just doesn't work that way. Unless you
make a total commitment, you will fail. You will need
to work long hours, face many disappointments, stretch
your mental capabilities, and learn to find order
among apparently chaotic facts. Unless you have
adopted the long-range goal of becoming a researcher,
the day-to-day demands will wear you down. Standards
will seem unnecessary high; rigor will seem
unwarranted. If you only consider it a test, you will
eventually walk away.
- The only research topic you will ever pursue
- Many students make the mistake of viewing their Ph.D.
topic as a research area for life. They assume each
researcher only works in one area, always pursues the
same topic within that area, and always uses the same
tools and approaches. Experienced researchers know
that new questions arise constantly, and that old
questions can become less interesting as time passes
or new facts are discovered. The best people change
topics and areas. It keeps them fresh and stimulates
thinking. Plan to move on; prepare for change.
- Easier than entering the work force
- You will find that the path to successful completion
of a Ph.D. becomes much steeper after you begin. The
faculty impose constraints on your study, and do not
permit unproductive students to remain in the program.
- Better than the alternatives
- For many students, a Ph.D. can be a curse. They must
choose between being at the top among people who hold
a Masters degree or being a mediocre researcher. The
faculty sometimes advise students that they must
choose between being "captain of the B team" or a
"benchwarmer" on the A team. Everyone must decide
what they want, and which profession will stimulate
them most. But students should be realistic about
their capabilities. If you really cannot determine
where you stand, ask faculty members.
- A way to make more money
- While we haven't heard any statistics for the past
couple of years, graduate students used to estimate
the "payoff" using the starting salaries of Ph.D. and
M.S. positions, the average time required to obtain
a Ph.D., the value of stock options, and current
return on investments. For a period of at least five
years that we know, the payoff was clearly negative.
Suffice it to say that one must choose research
because one loves it; a Ph.D. is not the optimum road
The good news:
Despite all our warnings, we are proud that we earned Ph.D. degrees and
proud of our research accomplishments. If you have the capability and
interest, a research career can bring rewards unequaled in any other
profession. You will meet and work with some of the brightest
people on the planet. You will reach for ideas beyond your grasp, and in so
doing extend your intellectual capabilities. You will solve problems that
have not been solved before. You will explore concepts that have not been
explored. You will uncover principles that change the way people use
The joy of research:
A colleague summed up the way many researchers feel about their profession.
When asked why he spent so many hours in the lab, he noted that the
alternatives were to go home, where he would do the same things that millions
of others were doing, or to work in his lab, where he could discover things
that no other human had ever discovered. The smile on his face told the
story: for him, working on research was sheer joy.