College Ceremony Oration:

Arthur E. Mills Memorial Oration: Professionalism and the Limitations of Information Technology

by The Honourable Sir Guy Green AC KBE CVO
Administrator Of The Commonwealth Of Australia

Hobart – Monday 26 May 2003

I feel greatly honoured to have been asked once again to deliver the Arthur E. Mills Memorial Oration.

One of the defining characteristics of our age has been the enormous increase in the extent to which the creation and application of knowledge and the making of decisions have been systematized and mechanized. Two of the most prominent techniques for doing so are by modelling and the use of algorithms. And of course over the last 30 years or so our capacity to employ those techniques has been greatly enhanced by the advent of the computer.

Let me start by given giving a brief background sketch of those two techniques.

I am not confining the word algorithm to its strict sense of a set of rules for performing mathematical operations – I am using it in its broader sense of any fixed predetermined step by step procedure for reaching a conclusion or making a decision.

The origins of mechanical or automatic calculating or processing can be seen in the abacus, the slide rule and a largely forgotten family of logic machines which replicate logical processes or statements through the settings of wheels on machines, window cards which can be slid over each other in various combinations and geometric figures such as Venn diagrams. But what turned out to be the most fruitful line of development consisted of electrical circuits or electronic states which replicated logical processes and statements; this comprised the use successively of simple switches, relays, vacuum tubes, transistors and finally the integrated circuits of the modern computer.

The concept of mechanical programming was applied in the 18th century Jacquard loom which used punched metal plates to specify the pattern of the cloth. This was followed by the use of punched cards, perforated paper, magnetized wire and tape and finally the modern computer programme.

It can thus be seen that the computer and the algorithm were not solely the product of 20th century science and technology. That is significant because it shows that the impetus to automate and mechanise intellectual and decision making processes is not just a characteristic of our generation – it has been with us for a long time. What distinguished the 20th century was the development of the technology which made the use of algorithms possible on an unprecedented scale.

The origins of that other ubiquitous tool of modern life, the model, go back at least as far as Pythagoras.

A model is in essence a mapping device. It can be a physical device like a scale model of say a building or a bridge upon which tests can be performed in order to predict how the real thing will behave. But it can also be a theoretical model which use mathematical or other forms of description to represent and make predictions about the behaviour of some part of the physical world.

Modelling is a useful way of doing science. Indeed in the general sense of it being a technique which involves the representation or mapping of a manageable sub-division of the physical world a great deal of science can be seen in essence to be a form of modelling. As with algorithms, the advent of the computer has resulted in a great increase in the use of modelling and simulation so that today it would be hard to find any field which does not rely upon some form of the technique. That represents a significant advance. Computer modelling is useful for generating hypotheses, it facilitates research and design and enables investigations to be undertaken and tests conducted that would otherwise be impossible or at least would be impossible to conclude within a reasonable period of time.

The scientific revolution of the 16th and 17th centuries marked the liberation of science from what John Dryden called the tyranny of scholastic Aristotelian orthodoxy. In this talk I would like to raise the question of whether the ubiquitousness and great utility of the new technology, and the rapidity with which it has been introduced may have given rise to a new form of scholastic orthodoxy: an orthodoxy which is characterised by a failure to appreciate the limitations of models and algorithms and a tendency to indiscriminately apply them to inappropriate fields.

Let me start with modelling.

A basic but common error is to forget that a model is not real. That sounds a rather obvious thing to say but it needs to be said because the output of models is routinely presented in such a way as to suggest that the thing represented by the model is the thing itself. Thus one frequently reads in scientific literature statements to the effect that a model or simulation “proves” or “shows” that something in the physical world is the case whereas the only statements which a model can make are statements about itself.

There is also a tendency to overlook the limitations of models including that by definition all models are incomplete and that the validity of the output of a model is dependent entirely upon the validity and scope of the assumptions upon which it is based.

A dramatic example of over reliance upon modelling was provided by the construction of the Millennium pedestrian bridge across the Thames. This magnificent structure had to be closed two days after it had been opened because the synchronised responses of pedestrians to random movements in the bridge set up dangerous oscillations. The failure to predict this phenomenon was a direct result of over reliance upon computer models and a failure to conduct sufficient empirical tests.

Arthur E. Mills Memorial Oration (cont.) >>

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