Comments
Having a standard way to negate resources would be extremely valuable. Negation (i.e. saying something has not been done or not been observed) is quite frequently encountered in FHIR, although how it is achieved is different in every resource. Sometimes, this is indicated by certain value(s) of a status element, and sometimes there are specific elements such as "wasNotGiven." Some resources that arguably should have negation possibility (e.g. Procedure) do not have a negation attribute. There is no consistency in how negation is handled across FHIR. Since negation is something that can occur for almost any action or observation (including Procedure), it would be useful to make this a general property or feature. If the method for indicating negation could be made consistent across FHIR, many things would become simpler and more transparent; for example, one could have a general search pattern to find exclude negated resources.

Grahame's Comments
Again, it makes no sense to negate non-action resources. Grahame/Bo to add this to the mix when looking at resource design consistency meta patterns

Disposition
Not Persuasive

Disposition Comment
Negation is introduced into core when it is "part of the 80%". I.e. When most systems typically capture negated instances as part of the same structure the use to capture non-negated instances. For places where this does not fall into the 80%, this is handled using extensions. If you feel the assertion of the 80% is not correct, then identify specific instances with evidence of broad existing implementer support.