This presupposition is derived from systems theory – the study of self-regulating systems. William Ross Ashby originally formulated the law to apply to controllers trying to keep a system stable – like the thermostat in a central heating system, to choose a very simple example.
Unfortunately (from a blogger’s point of view) Ashby doesn’t seem to have stated the law in a one-line form that makes sense out of context, but you can read a page or so of his ideas about it here. To put it into non-technical language, the law can be stated as: “the more options the controller has, the better able it is to deal with fluctuations in the system”.
Some people in NLP have reduced this to the idea that “the person with the greatest flexibility wins” – so the most flexible salesperson will be the one who closes the sale, or the most flexible manager will get their own way most often. This is a massive over-simplification. In his book “Whispering In The Wind” John Grinder points out that as any therapist knows, the idea of ‘controlling’ interaction with another human being is extremely optimistic.
Really, the law is more about adaptability and dealing with change. Think about dinosaurs. There were all kinds of shapes and sizes to make the most of various environmental niches. You had huge ones like the sauropods with long necks to browse from the tops of trees, you had horned ones like triceratops for browsing on grassland and seeing off predators, you had armoured spiky ones like ankylosaurus which were like living tanks.
During the last days when dinosaurs ruled the earth, the ancestors of mammals – our ancestors – were little furry animals resembling mice or shrews. They weren’t particularly specialised – they couldn’t run fast, they weren’t big enough to be good at fighting, they didn’t have wings or horns or armour. They pretty much kept out of the dinosaurs’ way.
Then, for whatever reason, the climate changed. Food became scarcer – and of course it takes a lot of food to keep something as big as a sauropod going. As they became scarcer, their predators, like the huge Tyrannosaurus Rex, also died out – there just wasn’t enough food available to keep sustain predators of that size.
The mammals survived because they were adaptable. They could eat pretty much anything, their coats and warm blood kept them warm, they had short reproductive cycles so they could recover quickly from population impacts when conditions improved again. They survived, and took over, because they had more options open to them.
So the Law of Requisite Variety in NLP is more about being able to adapt to change than about having to win everything. We might summarise it as “The more complex the situation you have to cope with, the more behavioural flexibility you need”, or even “If what you are doing isn’t working, do something different”.