Much can go wrong, and, inevitably, something always does. So your thesis planning has to mix practical thinking with scientific vision. Your adviser and readers will usually be quite concerned that you have considered both the practical and the visionary in your preparation for your thesis research. A judicious balancing of these approaches will help you produce a project that is interesting and meaningful enough to warrant the great time and effort it will require of you. In a thesis there is usually a clearly specific theoretical rationale as well as the provision of new empirical evidence.
Theoretical work is a necessary part of a thesis.
In contrast, the provision of new empirical evidence is not absolutely necessary as part of a contribution to knowledge. Empirical tests of the predictions of existing theories also contribute to knowledge by assessing the validity of current understanding. Finally, through the careful implementation of a well-motivated plan, a researcher can be reasonably assured of obtaining empirical evidence that makes a contribution to knowledge in that it provides constraints on theories of the domain in question. In contrast, conducting a successful theoretical thesis involves developing a new basis for explaining important empirical phenomena that is substantially and demonstrably better than previous explanations. Most theses done in the Department include substantial empirical work.