is almost complete consensus between physicists, and the interpretation of the meaning of the quantum mechanical concepts, where no agreement has been reached and all existing interpretations have been found wanting.

The ‘orthodox’ Copenhagen interpretation in terms of state reduction by external measurement loses credit because it becomes meaningless for the universe as a whole. There have been a number of proposals to change the structure of quantum mechanics, e.g., through pilot waves ([Bohm]{} [@Bohm]), consistent histories (e.g., [Omn[è]{}s]{} [@Omn]), event enhancement ([Blanchard & Jadczyk]{} [@BlaJ]), or gravitational objective reduction ([Penrose]{} [@Pen]).

Perhaps the main reason why there is so little progress on the meaning of quantum mechanical concepts is that it is usually seen as thoroughly enmeshed with measurement problems. I believe that this is a mistake, and that more clarity can be obtained by separating the analysis of meaning from that of observability. The discussion thereby becomes more concise and clear.

Here I refer to [*meaning*]{} as a conceptual, logically consistent mathematical framework that allows one to speak unambiguously about [*all*]{} the terms used in the theory, in a way intuitively related to corresponding concepts of external reality. This part is often elegant and concise.

On the other 