Engines of Our Ingenuity

No. 194:
WHAT'S REASONABLE?

by John H. Lienhard

Click here for audio of Episode 194.

Today, we expect to be surprised. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Gilbert and Sullivan warn us that,

Things are seldom what they seem,
Skim milk masquerades as cream;
Highlows pass as patent leathers;
Jackdaws strut in peacock's feathers
.

And a demographer named Joel Cohen agrees with them. He warns us that our complex world can surprise us.

For example, the first line of common sense says that adversaries will resolve their differences if they just sit down and talk. But when we describe negotiation mathematically, we have to include the rate at which negotiation hardens the positions of the negotiators. Whether opposing parties eventually agree, or trigger a nuclear holocaust, depends on how fast that hardening goes. Of course, that's why we have professional counselors and arbitrators. That's why we limit contact between leaders during summit meetings.

In another example, Cohen thinks about including crossroads between crowded highways. We certainly expect that crossroads will increase driver options and speed traffic. But analysis shows that such roads often make matters worse by creating local traffic jams.

Cohen shows that adding redundancy to a design doesn't always make it safer. He shows that successful paths of pursuit should often be indirect ones, and so forth. At first we're intrigued by his arguments, but then a second realization kicks in. It is that we'd live in a deadly dull world if common sense alone could lead us through all the mazes around us!

Technologists of every stripe are trained to think abstractly. They study mathematics and complex science. That's because it's the very nature of the creative process to take us where we don't expect to go. Analysis helps us to see things that direct vision doesn't reveal.

The simple fact is that if what we learn is what we expect to learn, then we haven't learned anything at all. Sooner or later, every student of heat flow finds out that adding insulation to a small pipe can sometimes increase the heat loss from it. You don't learn that from common sense. By the same token, no one ever put liquid in tension until a 19th-century scientist first showed that it was theoretically possible to do such a strange thing.

Common sense is that center of gravity that we return to from our flights of fancy. But it's the delicious surprise -- the idea that precedes expectation -- that makes science, technology, and invention such a delight to work in.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


Cohen, J.E., The Counterintuitive in Conflict and Cooperation. American Scientist, Vo. 76, No. 6, 1988, pp. 576-584.

This episode has been greatly revised as Episode 1778.



The Engines of Our Ingenuity is Copyright © 1988-1997 by John H. Lienhard.


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