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Proportionality; Ergonomics; Cognitive Reducibility

The following was posted to the alt.architecture newsgroup into a thread about metric/imperial measurement and is worth reproducing here:

The problem with the metric measurement as applied to architecture is that it violates three important parts of architectural composition/design:

1. Proportionality: The traditional (American Standard or British Imperial -- which are slightly different from each other, as any American who has ever worked on an old Jaguar knows) system of measurement was created by people who did not use digital calculators or need to measure machine parts to micrometer tolerances. It was created to measure out human scale objects in proportion to each other without complex calculations. For instance, most simple divisions of a foot result in whole number increments of inches (1/2=6", 1/3=4", 1/4=3", 1/6=2", etc.), while the only whole-number division proportion of a metric unit is either 1/2 or 1/5. This, in my opinion makes metric an inferior tool for proportional design.

2. Ergonomics: related to proportionality, the traditional measurement systems are specifically oriented toward the ergonomics of human physiology. They developed out of obscurity for precisely this reason. The human mind is geared toward judging its perceived environment in relation to the scale of its own body, not an arbitrary convention defined by the distance light will travel in a very short period of time (a centimeter or meter). Traditional systems of measurement are specifically oriented toward the mind's intuitive grasp of scale.

3. Cognitive Reducibility: Anyone familiar with cognitive science and/or epistemology will tell you that the human mind has a limited number of slots in its active consideration buffer. The average number of cognitive units any one person can consider at any one time ranges from 5 to 9, with 7 being very typical (ever wonder why telephone numbers usually have 7 digits? that's why). You will sometimes hear this referred to as the "Crow Epistemology" (from an observation about crows that they are incapable of distinguishing members of groups of entities greater than three).

The Crow Epistemology in humans means that we have to go to great lengths to cognitively reduce the number of items we are considering at any one time when dealing with complex issues. Design measurements are one such case. It is much easier for me to remember that I am 6'-5" tall than to remember that I am 195.58 cm or 1.9558 m tall. the difference is between two cognitive units and six (including the decimal point). Similarly, the proportional and ergonomic relationships described above are likely to be more consistently applied for this same reason.

Before I get flamed for putting down the hallowed Metric System, let me state that I have experience in using SI on real projects in Australia, and have found the above to be true in practice (laying out building foundations in centimeters makes about as much sense as laying them out in multiples of half-inches--i.e. 975 cm or 768/2" vs. 32 feet). The primary value of SI applies to the sciences, where the above issues are not of high importance. Architecture, however is not science. I argue that adopting metric merely because our calculators don't do standard is a silly reason, and does harm to good design.

Actually, based on the above argument, I would propose that Metric would be a much better measurement system if it were modified in the following ways:

  1. Made into a base-12 system on all scales, rather than base-10
  2. Re-scaled to human ergonomics

A measurement system is like any tool -- you've got to use the right one for the job. The right tool for the job of architecture is not metric. American Standard may not be the right tool for that job either (certainly debatable). However, it does have some inherently superior qualities with regard to architectural design. Archtitects throughout the ages have been trying to come up with an ideal measurement system for architecture (classical orders, Corbusier, etc.). None have totally succeeded yet. My argument was that the uniform, unthinking adoption of Metric will set that progress back, not contribute to it.

Now, I am not saying that Metric is a bad system of measurement. I am merely saying that it is not really well suited to doing architecture. There are ways it could be made more suitable, while retaining some of its inherent benefits, but that is another issue.

Additional note:
Some others have been stating that we need metric to have international standards of measurement. I argue that these people obviously have little experience dealing with countries other than their own. Nearly every nation which uses the metric system uses a slightly different version of it, just as the American version of British Imperial (known as American Standard) is not exactly the same as British Imperial. Measurement standards are great things to pay lip service to, but putting them into practice never seems to work out as perfectly as their proponents would like. Japanese metric, Australian Metric, and French Metric all have their quirks and eccentricities. Granted, these tend to be most pronounced at a small scale (auto parts, being a major one), but the point is important.

Standards of measurement are tools, nothing more. Different people use different tools for different jobs. The Metric Gestapo needs to start taking this into account, as do those who resolutely refuse to consider anything other than Imperial or Standard. There is plenty of intellectual laziness being displayed in both camps, on what is really a very simple issue. I brought this whole subject up just so that people would think about it, and maybe apply themselves to dreaming up a new standard superior to both.

J. Gregory Wharton
Architect / Philosopher
Seattle, Washington, USA




10 nov 99