A useful starting-point in considering the theory-practice problem is that any professional or semi-professional practice has a body of theory to which it relates. Historically, it has been the development of a body of theoretical knowledge with a clear relationship to either the natural or the human/social sciences, which has marked out a practice as a ‘profession’. However, at the same time, it has been precisely the possession of a body of theoretical knowledge and what the relationship of this knowledge is to practice that has been the source of problems.