Description versus interpretation
A recent examiner has noted that the thesis he was considering was heavy on description but light on interpretation. He thought that descriptive theses are acceptable at the Masters level but that the goal of the PhD is to generate new knowledge and go beyond description.
This is an interesting point that has come up in lots of examiners' reports. It is at the core of the question about how much theory a PhD thesis should contain. So what is the answer?
Our university's definitions state the following:
The Masters thesis must be a substantial work generally based on independent research, showing sound knowledge of the subject, some evidence of independent thought, and it must be presented in clear and concise language.
The PhD thesis must make a substantial and original contribution to knowledge.
Neither of these definitions makes reference to a distinction between description and interpretation, nor to theory, yet this is a point that examiners come back to again and again. A thesis that merely describes the state of the subject area (the facts) will have more difficulty passing as a PhD than one that explores the meaning of these facts. The meaning, or the interpretation, is the basis of the theory, and a theory has predictive power: it allows the consumer of this new knowledge to know more than the mere collection of presented facts. A theory provides an insight that can be applied to other, similar, systems of study.