&gt; ... and then someone finds a bug in the <i>specification</i> which is provably correctly implemented.<p>As a programmer, if the specification is wrong, it&#x27;s Not My Fault (tm). If you want me to write specifications, well, pay me to do it! I guarantee dramatically better results than the usual crap.<p>&gt; The machine as a whole isn&#x27;t provably correct.<p>As a programmer, defects in the machine are Not My Problem (tm). In any case, hardware vendors have a much better track record than software developers at delivering products that meet strict quality standards.