Why Don't People Use Formal Methods?
Formal methods don't make a lot of sense when the product changes from week to week, or month to month, or even year to year.It seems like the advocates of formal methods assume a waterfall method of software development wherein you develop a spec, formalize it, prove that it works, and then deliver it. That's just not how software works in industry. A lot of it never had formal specs and never will, and whatever specs exist change frequently. By the time a spec is perfected it is out of date and we are already moving on to the next thing.Agile development killed waterfall development and formal methods have not adapted to the agile methodology.