Recently a friend of mine told me “I can’t get my head around the law of requisite variety”. I’ve heard that before. I have also heard the opposite and sometimes found it wasn’t the case. That’s why I wrote Variety – part 1 and part 2 back in 2013. Part 3 wasn’t that lucky to get published. But whatever was there and much more is now written and will be published as part of chapter 4, “Stimuli and Responses,” in the forthcoming book Essential Balances. Until then, here’s an elaboration of my response to “I can’t get my head around the law of requisite variety”.

First, as a reminder of the law, I’ll just reuse a paragraph from Variety – part 1 :

It’s stated as “variety can destroy variety” by Ashby and as “only variety can absorb variety” by Beer, and has other formulations such as “The larger the variety of actions available to control system, the larger the variety of perturbations it is able to compensate”. Basically, when the variety of the regulator is lower than the variety of the disturbance, that gives high variety of the outcome. A regulator can only achieve desired outcome variety if its own variety is the same or higher than that of the disturbance.

That sounds way too technical, so we need an example. As this medium is text, it will be easier to count the variety of words. The variety of cuckoo is four, as there are four different letters. If your goal is to count the variety of a word, as long as you can distinguish these letters, you have enough variety to achieve your goal. But what about the variety of melon and lemon? It’s five for both of them. If these are two hands of five playing cards, they are exactly equal in strength. But that doesn’t mean there won’t be a winner. The cards will be played in certain order. And it is also (and only!) the order of letters that helps us distinguish melon and lemon. The different type of letters, size and order all may participate in measuring the variety of a word. If the font or the colour of letters is different, that would be another criterion for distinction, depending on how it matters for the goal that you have. And then, there was the assumption that the elements of a word are the letters, which is a common and fair assumption. But if your goal is to print them clearly, then you would be more interested in the number of pixels¹You won’t have this problem with the sketch below as it’s in vectors. You can scale it up as much as you want without loss of quality..

Like gravity, the Law of Requisite Variety is omnipresent. Whenever there are purpose and interaction, it’s there. To demonstrate this, I can use just the complaint that triggered this post: “I can’t get my head around the law of requisite variety”. It contains this popular idiom “I can’t get my head around” which can be seen as a conceptual metaphor²See Metaphors We Live By and Philosophy in the Flesh by Lakoff and Johnson. See also here QUTE and Human Resources? for some examples. where a certain problem or theory is seen as something physical, and the ability to wrap it is the ability to understand it.

• 1
  You won’t have this problem with the sketch below as it’s in vectors. You can scale it up as much as you want without loss of quality.
• 2
  See Metaphors We Live By and Philosophy in the Flesh by Lakoff and Johnson. See also here QUTE and Human Resources? for some examples.