W. Ross Ashby is one of the founding fathers of both cybernetics and systems theory. He developed such fundamental ideas as the homeostat, the law of requisite variety, the principle of self-organization, and the principle of regulatory models. Many of these insights were already proposed in the 1940's and 1950's, long before the presently propular "complex adaptive systems" approach arrived at very similar conclusions. Whereas the concepts surrounding the complexity movement are often complicated and confused, Ashby's ideas are surprisingly clear and simple, yet deep and universal.

Photo: W.R. Ashby, dec. 1955, Stanford (Copyleft. 2002. No Rights Reserved)

This elegance of thought is illustrated in particular by the present book, which is still the only real textbook on cybernetics (and, one might add, system theory). It explains the basic principles with concrete examples, elementary mathematics and exercises for the reader. It does not require any mathematics beyond the basic high school level. Although simple, the book formulates principles at a high level of abstraction. For more concrete and extensive illustrations of systems principles, you may refer to our other electronic books, "The Macroscope" and "The Phenomenon of Science". For a similar abstract, high-level, but technically simple approach, this time to physics, you can check "Representation and Change".

The electronic version of Ashby's book has been formatted as a PDF file (1.9 Mb), with two pages of the original book per printed A4 page. This format, although it can be read on-screen, is basically meant for printing out. The print-out will be similar to the original book, including the original figures, formulas, answers to exercises, table of contents and index. You can read or print it with the free PDF reader from Adobe.

Table of Contents 1: WHAT IS NEW

The peculiarities of cybernetics

The uses of cybernetics

PART ONE: MECHANISM

2: CHANGE

Transformation

Repeated change

3: THE DETERMINATE MACHINE

Vectors

4: THE MACHINE WITH INPUT

Coupling systems

Feedback

Independence within a whole

The very large system

5: STABILITY

Disturbance

Equilibrium in part and whole

6: THE BLACK BOX

Isomorphic machines

Homomorphic machines

The very large Box

The incompletely observable Box

PART TWO: VARIETY

7: QUANTITY OF VARIETY

Constraint

Importance of constraint

Variety in machines

Transmission from system to system

Transmission through a channel

9: INCESSANT TRANSMISSION

The Markov chain

Entropy

Noise

PART THREE: REGULATION AND CONTROL

10: REGULATION IN BIOLOGICAL SYSTEMS

Survival

11: REQUISITE VARIETY

The law

Control

Some variations

12: THE ERROR-CONTROLLED REGULATOR

The Markovian machine

Markovian regulation

Determinate regulation

The power amplifier

Games and strategies

13: REGULATING THE VERY LARGE SYSTEM

Repetitive disturbance

Designing the regulator

Quantity of selection

Selection and machinery

14: AMPLIFYING REGULATION

What is an amplifier?

Amplification in the brain

Amplifying intelligence

REFERENCES

ANSWERS TO EXERCISES

INDEX

