The final component of the MAIR is a 15 000 word thesis on a topic the student devises in consultation with their supervisor. 

A thesis might apply an established theory to a new body of evidence or set of cases.  It might try to develop a new theory about well known evidence.  A major part of the thesis writing process is establishing what research question you will ask and how you will go about answering that question.  The thesis should be an extended arguement addressing an intellectual question, problem or issue.  As it is 15 000 words in length, it must be divided into a number of sections or chapters, with an introduction and conclusion.