Why logic rules

NZ Lifestyle Block - - Contents - Words Mur­ray Grim­wood

We can some­times credit in­di­vid­u­als with su­per­hu­man pow­ers. The peo­ple who seem to ar­rive at ge­nius so­lu­tions while the rest of us are still for­mu­lat­ing the ques­tion.

It took me a long time to work out that logic was all we need. It gets us non-ein­steins 90% of the way down the track for free. But think­ing log­i­cally re­quires us to di­vest our­selves of in­stincts, as­sump­tions and be­liefs. It’s no mean feat.

I dis­tinctly re­mem­ber the day my per­sonal penny dropped. I was in a Bondi back­yard, sweat­ing, strug­gling to re-en­gine a Fal­con ute to tow the boat we’d built. The pres­sure was on be­cause we’d ter­mi­nated our lease.

The old clutch had been a me­chan­i­cal link­age on the driver’s side but the new one was hy­draulic and on the other side. When we pushed the old top-hung pedal down we needed to phys­i­cally pull the new clutcharm back to­wards the pas­sen­ger seat.

Thoughts turned to a Bowden ca­ble, the ones you get on push-bike brakes where a wire moves in­side a tube. We found a hefty one from the hand-brake of a derelict Valiant, then used a yacht­ing pul­ley bolted un­der the dash­board so the in­ner wire went from the pedal, around the pul­ley, back through the fire-wall, through the outer ca­ble (the tube) and bent around un­der the en­gine.

But it wasn’t long enough to bend round and face for­ward so we could pull the arm back with the in­ner wire in the time-hon­ored man­ner. Out of ideas, I made a quick call from a phone box (this was 1980) to Dad in Dunedin.

He had no idea what I was do­ing. It took him two sec­onds to solve the prob­lem from a stand­ing start.

“Why don’t you put the outer against the clutch-arm, and bolt the in­ner to the floor un­der the seat? They’ll still pull to­wards each other.” Ge­nius. I won­dered how it was he could get there so quick. He dis­agreed. He said he’d just turned the prob­lem into a log­i­cal ques­tion. The mis­take I’d made was in pre­sum­ing that only the in­ner ca­ble could do the mov­ing, be­cause I’d never seen any­thing else.

When you study what we con­sider to be other peo­ple’s land­mark ef­forts of ge­nius, you find that many of them were just hard slogs gath­er­ing em­pir­i­cal data.

Wil­bur Wright did it with flight. He rea­soned that there would be a best wing­shape. He built a wind tun­nel, ap­plied spring bal­ances and tested shape af­ter shape. He did the same with pro­pel­lers, pro­file af­ter pro­file tested, tested, tested.

He didn’t be­gin by at­tempt­ing to fly a mo­tor or even a hu­man. First it was a teth­ered glider, then a manned glider, then he added a mo­tor. Em­pir­i­cal, log­i­cal.

Wil­bur spent his fi­nal years try­ing to de­fend his in­ven­tion. And los­ing. You can un­der­stand why he in­stinc­tively did so. If you’ve just spent the best years of your life search­ing for the op­ti­mal wing shape, pro­peller pro­file and all the rest, you can be for­given for think­ing you’ve pro­duced the ul­ti­mate.

We know now that tech­nolo­gies like Wil­bur’s tend to be im­proved upon, rapidly. Just 30 years later we would see the DC3, and 70 years later we had the stun­ning Con­corde and 747, af­ter which im­prove­ments be­came in­cre­men­tal. Wil­bur could have worked that out if he’d ap­plied logic.

Once I’d learnt the les­son of logic, it was easy to ap­ply it. Down­hill trol­ley rac­ing? Three wheels must be less re­sis­tant than four, a long trol­ley won’t be as twitchy to steer (and thus will waste less en­ergy) and the driver ly­ing prone must in­duce the least air re­sis­tance.

Ef­fi­cient fridge? Must be top-load­ing (so the cold air doesn’t fall out) and placed out­side the house, prefer­ably on the south side (no need to work as hard and some­times no need to work at all).

And so on. A life based on iden­ti­fy­ing the prob­lem and work­ing out the sim­plest, least-ef­fort way of solv­ing it. Of­ten, that turns out to be the cheap­est too.

An added bonus. If you asked me what our so­ci­ety is most short of, logic would be the only item on the list. With­out it, you’re just rolling dice. n

A Bowden ca­ble. Wil­bur and Orville Wright’s first flight. Photo: John T Daniels, United States Li­brary of Congress’s Prints and Pho­to­graphs

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