Beer, [30] and [31], has
proposed that the purpose of a system is ‘what it does’.
In considering the implications for PMSs, we restate
the point as ‘a system can only produce what it is
capable of producing.’ Capability is a function of both
design and execution of the system. The resulting
system outputs (patterns, products, and services) and
outcomes (impacts) of the system in operation are ‘the’
products of the system, regardless as to whether or not
we have a complete understanding of the system.