The world about us can be looked at in a variety of ways. One way is to see the world as made up from many interacting systems: weather, societal, ec… - Derek Hitchins

A system is an open set of complementary, interacting parts, with properties, capabilities and behaviours of the set emerging both from the parts and from their interactions to synthesize a unified whole.

Hard systems viewpoints are basically those held by designers and engineers who are trying to create systems to meet an understood need in an effective and economic manner. Those in the soft camp caricature the approach as head-down, concerned with optimization, obsessed with quantitative metrics and highly pragmatic. So much so, in fact, that the term system thinking has been purloined by the soft camp as though they alone thought! The soft camp use the term engineer’s philosophy, not too endearingly, to describe the hard approach, in which the requirement is stated by a customer and the engineer satisfies the requirement without question.

The motives for conceiving modern systems engineering are to be found, at least in part, in past disasters. Arthur D. Hall III cites: the chemical plant leakage in Bhopal (1986); the explosion of the NASA Challenger space shuttle (1986) and the Apollo fire (1967); the sinking of the Titanic (1912); the nuclear explosion in Chernobyl (1986) and the disaster at Three Mile Island power plant (1979). He cites, too, the capture of markets by Japan from the U.S., the decline in US productivity and the failure of the US secondary school system. He identifies the millions of people dying of starvation every year while other nations stockpile surplus food, medical disasters such as heart disease, while governments subsidize grains used to produce high cholesterol meat, milk and eggs; and many more. One implication is clear: systems engineering faces challenges well beyond the sphere of engineering.