This is an interesting discussion, but unfortunately the term observability is overloaded. It is used in control theory as "a measure for how well internal stat

This is an interesting discussion, but unfortunately the term observability is overloaded. It is used in control theory as "a measure for how well internal states of a system can be inferred by knowledge of its external outputs" [1]. For several years I've been using the term "inspectability" to refer to the kind of observation of code execution to which the author refers. Inspectability is an important concept, especially for computer security, and is not often discussed. It's interesting to note that malware written in a language like OCaml would often be harder to reverse engineer than malware written in C, precisely because of the points the author makes. http://en.wikipedia.org/wiki/Observability http://en.wikipedia.org/wiki/Observability