Chapter 4. Ashby’s Law of Requisite Variety

Marcus Guest
5 min readSep 22, 2021


Pal’chinskii’s first principle was: Increase your chances of success by seeking out and experimenting with a variety of ideas. A few decades later W. Ross Ashby, a leading British scientist, echoed this principle in “An Introduction to Cybernetics”.[⁠1] Cybernetics is the science of communication and control in living and mechanical systems and what would become known as it’s ‘first law’ was ‘Ashby’s Law of Requisite Variety’, which stated that: If a system is to adapt to change its control mechanism must have at least as much variety as that found in the external environment. In other words, if the world is changing faster than your ability to respond to it you’re in trouble.

To understand ‘Ashby’s Law’ picture a room with a thermostat that’s linked to a heating system. The thermostat continually monitors the room’s temperature and, when it reaches a certain level, it switches the heating on (or off). If, however, the thermostat only checked the room’s temperature once a day it would switch the heating on (or off) too infrequently, meaning the room would become too hot (or too cold) for much of the day. In this situation the thermostat is the control mechanism and, if it’s going to respond effectively to any changes in temperature, it needs a sufficient variety of information flowing in.

In organisations management is the control mechanism choosing what to focus on, the people hired to do this, the incentives they are offered and the structure, processes and technologies invested in to help them deliver positive results. Yet unlike thermostats, which are engineered to control mechanical systems, managers are fallible human beings trying to control organic, unpredictable, living systems. And as humans — with a natural human aversion to uncertainty [⁠2] — managers often treat their organisations the way they wished they were (predictable machines) rather than how they really are (unpredictable organisms). Managers desperate for certainty and control in an uncertain and volatile world often simplify reality to make it manageable: Contrarian people (mavericks) are overlooked in favour of those considered a better ‘cultural fit’, (i.e. more of the same type of people); disruptive, risky ideas are ignored in favour of imitating “best practices⁠”[3] and knowable outputs are measured against Key Performance Indicators (KPIs) so the organisation operates like a well-oiled machine.

Forcing the messy reality of an organic world into ordered, repeatable mechanical processes helps managers create the comforting sense of certainty and control many seek. But it also creates a critical deficiency. When new ideas are continually left unexplored organisations fail to develop the requisite variety of responses they need to adapt when a shock (a game-changing new technology, a global crash, a pandemic) hits their system. When the landscape shifts these organisations are unable to respond as they’ve only ever relied on one way of doing things. Their only hope is for everything to go “back to normal” soon — but hope is rarely a viable strategy.

Adaptivity Intelligence (AQ)

Organisations lacking a requisite variety of responses to change are suffering from ‘Low-AQ’ (Adaptivity Intelligence) — they are “dead players”[⁠4] ‘incapable of working off-script and doing new things’. In contrast, organisations that have cultivated a requisite variety of responses over time by experimenting with new ideas and learning from them tend to be ‘High-AQ’ organisations — “live players” ‘able to do things they have not done before’. When told that something is “best practice” live players ask: Why is this best practice? for whom is this best practice? when was this best practice? and do those conditions apply to us today? Rather than unthinkingly imitating someone else’s ‘past practices’ they experiment with these ideas to discover what’s valuable (and what’s not) for them. They’re following Pal’chinskii’s first principle: Increasing their chances of success by seeking out and experimenting with a variety of ideas ahead of time (rather than scrambling to respond — often when its too late).

Live players protect themselves from the uncertainty inherent in the new by embracing Pal’chinskii’s second principle: Failure is inevitable, so do things on a small enough scale that it’s survivable. They don’t go all in on a single big bang change (ex, a digital, cultural or agile transformation) as they know major projects designed to shift them to some ideal future state are rarely completed before the world shifts again and they must adapt once more. Therefore they experiment with new ideas on a small-enough scale that any inevitable failure won’t cause a collapse. This safe-to-fail [5] approach means they can afford to experiment with multiple, even contradictory ideas, in order to learn more quickly what works or what doesn’t.⁠ This is how live players become High-AQ organisations — by developing the requisite variety of responses needed to not only survive but also thrive in a volatile and changing world.

Fig. 9: Ashby’s Law of Requisite Variety and Adaptivity Intelligence (AQ)

Adapted from ‘Complexity and Organization–Environment Relations: Revisiting Ashby’s Law of Requisite Variety’. Boisot and McKelvey (2011)

If managers are to be an effective control mechanism in organisations — like the thermostat continually checking the room’s temperature — they need to encourage greater inward flows of information from which new ideas emerge and can be tested. However, more information also means more ‘noise’ and uncertainty as information is often complex, ambiguous, unreliable or incomplete. And this is where Pal’chinskii’s third principle comes in: Quickly identify and select what’s working in the local context by developing effective feedback loops between decision-makers and those closest to the action. Organisations have to get their closer to their customers or end user to learn what they could and should be doing more or less of. Organisations need to attract employees with diverse backgrounds, varied experiences, and alternative ways of thinking to increase the breadth of perspectives so, rather than choosing a single path forward — such as an industry ‘past practice’ marketed as “best practice” — they can experiment with new ideas and find the next best move forward for them at this time. Continually making moves and learning as they go is how High-AQ organisations develop the requisite variety of responses they need to adapt and thrive in a changing world. In the next chapter we’ll take a look at one such organisation.

1 An Introduction to Cybernetics. W. Ross Ashby (1956)

2 See Chapter 1

3 On the futility of copying ‘best practices’ see the Introduction


5 This is the approach advocated in the Cynefin Framework when dealing with complex situations: Probe-Sense-Respond, which privileges launching experiments (probes) to learn what works or doesn’t in a particular context. Probes that have positive outcomes are then amplified, while probes with negative outcomes are dampened (and learnings are fed through to new probes).



Marcus Guest

Govern the state by being straightforward; And wage war by being crafty. — Laozi, Tao Te Ching

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