The note is aimed at informed commentators and therefore takes some knowledge for granted – for example of terminology, recent literature and the principal concepts. Its focus is on why and where opinions differ, and the objective is to highlight questions and disagreements, but not answer or resolve either. A more general introduction to the subject is provided in the project scoping note and protocol.
Feedback and comment is invited on all of what follows, and in particular on the set of summary questions at the end of this note.
The remainder of this note covers the following topics: