Mick McQuaid

What are principles? Tufte tells us that we should do certain things. In Tufte (2006), he tells us that we should show comparisons, contrasts, differences. It’s his first principle of analytic design. In what sense is this a principle? How do we know that this is what we should do. I shared this “principle” with one of the most successful scholars I know, Judy Olson, and she replied that we should show what’s surprising. We should show differences where those differences are meaningful, but we should show similarities where those are meaningful. Some trends are surprising; some similarities are surprising.

It is not at all clear that these principles are grounded in any kind of theory. At the beginning of my other class, I offer a lengthy quote from Stephen Hawking about theory in A Brief History of Time on page 7.

A theory is a good theory if it satisfies two requirements. It must accurately describe a large class of observations on the basis of a model that contains only a few arbitrary elements, and it must make definite predictions about the results of future observations. For example, Aristotle believed Empedocles’s theory that everything was made out of four elements, earth, air, fire, and water. This was simple enough, but did not make any definite predictions. On the other hand, Newton’s theory of gravity was based on an even simpler model, in which bodies attracted each other with a force that was proportional to a quantity called their mass and inversely proportional to the square of the distance between them. Yet it predicts the motions of the sun, the moon, and the planets to a high degree of accuracy.

Note that Hawking is giving what we might call a normative definition, telling us what a theory should be. There might be plenty of things parading around under the theory banner that could be classed as bad theory. Note also that Hawking requires that a theory both describe and predict.

Why does theory have value? The theory of gravity can be used to decide what to do in a wide variety of situations. A theory of analytic design could be used to tell us about the causes and effects of different actions we take as designers. But what about the Principles of Analytic Design as articulated in Tufte (2006)? What are they good for? For example, the sixth principle tells us that content counts most of all. I sincerely hope that you don’t believe that and that you instead believe that content alone doesn’t count for much. There would be lines around the block at the Library of Congress otherwise. Clearly, I am not suggesting that you take Tufte’s principles at face value. So, why then, do I recommend reading his work?

Part of the answer can be found in Tufte (2003), where he discusses the Cognitive Style of Powerpoint. Tufte rails against a badly designed presentation tool that makes a lot of choices for you and makes most of the choices poorly. While railing, Tufte does what Tufte does best (and what you can also see on his blog): he demonstrates his ability to carry on a data-laced conversation. I believe that, to do this effectively, it helps to be exposed to exemplary work. For this reason, and this reason alone, I think it’s worthwhile to familiarize yourself with the normative perspective. Another way to familiarize yourself with this kind of work is to look at the Mathematica notebooks of our colleague Eytan Bakshy. In fact, let me use this opportunity to call upon Eytan to share a suitable example with us as another aid to our conversation about what you should and shouldn’t do.