Derek Hitchins quotes
The term (system-of-systems) is being applied to the creation of new systems by bringing together existing operational systems under a single umbrella and, presumably, creating or adapting links and interactions between the operational systems, which become subsystems of the higher level umbrella system..
Derek Hitchins
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, economic, ecological, floral, faunal, tectonic plate, oceanic, and so on. This is very much a connected view of the world: nothing is isolated and totally independent; everything is part of something bigger, and everything comprises many interacting parts - subsystems.
Derek Hitchins
Soft systems viewpoints are those held by behavioural, management, social anthropology, social psychology and other science students concerned with observing the living world, and in particular the human world. Human activity systems (HASs) are messy, in that they do not exhibit a clear need or purpose - if they can be said to exhibit purpose at all. Indeed, so complex is the real world of people that the idea of driving towards optimal solutions may be a non-starter - perhaps we should see if we can simply understand and concern ourselves with improving the situation.
Derek Hitchins
Emergence is not really mysterious, although it may be complex. Emergence is brought about by the interactions between the parts of a system. The galloping horse illusion depends upon the persistence of the human retina/brain combination, for instance. Elemental gases bond in combination by sharing outer electrons, thereby altering the appearance and behavior of the combination. In every case of emergence, the source is interaction between the parts - sometimes, as with the brain, very many parts - so that the phenomenon defies simple explanation.
Derek Hitchins
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.
Derek Hitchins
The motives for conceiving modern systems engineering are to be found, at least in part, in past disasters. Arthur D. Hall III [1989] 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.
Derek Hitchins
