 A full account must say much more than this about precisely what it is to consider a scenario as actual, and what it is for a scenario to be endorsed by a particular belief. In order to consider a scenario, we must have a complete description of some sort. On the other hand, there must be restrictions on the vocabulary in which the description is expressed. In particular, it cannot contain expressions like ‘water’, for which Twin Earth examples can be constructed. Chalmers offers a detailed account that addresses such questions. (This is presented briefly in Chalmers 2002 and Chalmers 2003, and in much more detail in Chalmers 2006.) Here is the short version (Chalmers 2002, p. 611):