Pitfalls of formality in early system design

One of the advantages of using formal methods in design should be that we can be precise about where our methods fail. However, it is rare to find discussions in the literature of problems in applying formal methods—particularly in the early stages of design. One reason for this is that failures are often caused by the context in which a method is applied, rather than by some purely technical limitation. Using examples from research in which I have been involved I shall describe some of the pitfalls I have encountered and which I have observed frequently in the research of others.