Gary Marcus


The Haphazard Construction of the Human Mind


It has been said that man is a rational animal. All my life I have been searching for evidence which could support this.


ARE HUMAN BEINGS “noble in reason” and “infinite in faculty” as William Shakespeare famously wrote? Perfect, “in God’s image,” as some biblical scholars have asserted? Hardly.

If mankind were the product of some intelligent, compassionate designer, our thoughts would be rational, our logic impeccable. Our memory would be robust, our recollections reliable. Our sentences would be crisp, our words precise, our languages systematic and regular, not besodden with irregular verbs (sing-sang, ring- rang, yet bring-brought) and other peculiar inconsistencies. As the language maven Richard Lederer has noted, there would be ham in hamburger, egg in eggplant. English speakers would park in parkways and drive on driveways, and not the other way around.

At the same time, we humans are the only species smart enough to systematically plan for the future — yet dumb enough to ditch our most carefully made plans in favor of short-term gratification. (“Did I say I was on a diet? Mmm, but three-layer chocolate mousse is my favorite… Maybe I’ll start my diet tomorrow?) We happily drive across town to save $25 on a $100 microwave but refuse to drive the same distance to save exactly the same $25 on a $1,000 flat-screen TV. We can barely tell the difference between a valid syllogism, such as All men are mortal, Socrates is a man, therefore Socrates is mortal, and a fallacious counterpart, such as All living things need water, roses need water, therefore roses are living things (which seems fine until you substitute car batteries for roses). If I tell you that “Every sailor loves a girl,” you have no idea whether I mean one girl in particular (say, Betty Sue) or whether I’m really saying “to each his own.” And don’t even get me started on eyewitness testimony, which is based on the absurd premise that we humans can accurately remember the details of a briefly witnessed accident or crime, years after the fact, when the average person is hard pressed to keep a list of a dozen words straight for half an hour.

I don’t mean to suggest that the “design” of the human mind is a total train wreck, but if I were a politician, I’m pretty sure the way I’d put it is “mistakes were made.” The goal of this book is to explain what mistakes were made — and why.

Where Shakespeare imagined infinite reason, I see something else, what engineers call a “kluge.” A kluge is a clumsy or inelegant — yet surprisingly effective — solution to a problem. Consider, for example, what happened in April 1970 when the CO2 filters on the already endangered lunar module of Apollo 13 began to fail. There was no way to send a replacement filter up to the crew — the space shuttle hadn’t been invented yet — and no way to bring the capsule home for several more days. Without a filter, the crew would be doomed. The mission control engineer, Ed Smylie, advised his team of the situation, and said, in effect, “Here’s what’s available on the space capsule; figure something out.” Fortunately, the ground crew was able to meet the challenge, quickly cobbling together a crude filter substitute out of a plastic bag, a cardboard box, some duct tape, and a sock. The lives of the three astronauts were saved. As one of them, Jim Lovell, later recalled, “The contraption wasn’t very handsome, but it worked.”

Not every kluge saves lives. Engineers sometimes devise them for sport, just to show that something — say, building a computer out of Tinkertoys — can be done, or simply because they’re too lazy to do something the right way. Others cobble together kluges out of a mixture of desperation and resourcefulness, like the TV character MacGyver, who, needing to make a quick getaway, jerry-built a pair of shoes from duct tape and rubber mats. Other kluges are created just for laughs, like Wallace and Gromit’s “launch and activate” alarm clock/coffeemaker/Murphy bed and Rube Goldberg’s “simplified pencil sharpener” (a kite attached to a string lifts a door, which allows moths to escape, culminating in the lifting of a cage, which frees a woodpecker to gnaw the wood that surrounds a pencil’s graphite core). MacGyver’s shoes and Rube Goldberg’s pencil sharpeners are nothing, though, compared to perhaps the most fantastic kluge of them all — the human mind, a quirky yet magnificent product of the entirely blind process of evolution.

The origin, and even the spelling, of the word kluge is up for grabs. Some spell it with a d (kludge), which has the virtue of looking as clumsy as the solutions it denotes, but the disadvantage of suggesting the wrong pronunciation. (Properly pronounced, kluge rhymes with huge, not sludge.)[1] Some trace the word to the old Scottish word cludgie, which means “an outside toilet.” Most believe the origins lie in the German word Kluge, which means “clever.” The Hacker’s Dictionary of Computer Jargon traces the term back at least to 1935, to a “Kluge [brand] paper feeder,” described as “an adjunct to mechanical printing presses.”

The Kluge feeder was designed before small, cheap electric motors and control electronics; it relied on a fiendishly complex assortment of cams, belts, and linkages to both power and synchronize all its operations from one motive driveshaft. It was accordingly temperamental, subject to frequent breakdowns, and devilishly difficult to repair — but oh, so clever!

Virtually everybody agrees that the term was first popularized in February 1962, in an article titled “How to Design a Kludge,” written, tongue in cheek, by a computer pioneer named Jackson Granholm, who defined a kluge as “an ill-assorted collection of poorly matching parts, forming a distressing whole.” He went on to note that “the building of a Kludge… is not work for amateurs. There is a certain, indefinable, masochistic finesse that must go into true Kludge building. The professional can spot it instantly. The amateur may readily presume that ‘that’s the way computers are.’”

The engineering world is filled with kluges. Consider, for example, something known as vacuum-powered windshield wipers, common in most cars until the early 1960s. Modern windshield wipers, like most gizmos on cars, are driven by electricity, but back in the olden days, cars ran on 6 volts rather than 12, barely enough power to keep the spark plugs going and certainly not enough to power luxuries like windshield wipers. So some clever engineer rigged up a kluge that powered windshield-wiper motors with suction, drawn from the engine, rather than electricity. The only problem is that the amount of suction created by the engine varies, depending on how hard the engine is working. The harder it works, the less vacuum it produces. Which meant that when you drove your 1958 Buick Riviera up a hill, or accelerated hard, your wipers slowed to a crawl, or even stopped working altogether. On a rainy day in the mountains, Grandpa was out of luck.

What’s really amazing — in hindsight — is that most people probably didn’t even realize it was possible to do better. And this, I think, is a great metaphor for our everyday acceptance of the idiosyncrasies of the human mind. The mind is inarguably impressive, a lot better than any available alternative. But it’s still flawed, often in ways we scarcely recognize. For the most part, we simply accept our faults — such as our emotional outbursts, our mediocre memories, and our vulnerability to prejudice — as standard equipment. Which is exactly why recognizing a kluge, and how it might be improved upon, sometimes requires thinking outside the box. The best science, like the best engineering, often comes from understanding not just how things are, but how else they could have been.

If engineers build kluges mostly to save money or to save time, why does nature build them? Evolution is neither clever nor penny-pinching. There’s no money involved, no foresight, and if it takes a billion years, who’s going to complain? Yet a careful look at biology reveals kluge after kluge. The human spine, for example, is a lousy solution to the problem of supporting the load in an upright, two-legged creature. It would have made a lot more sense to distribute our weight across four equal cross-braced columns. Instead, all our weight is borne by a single column, putting enormous stress on the spine. We manage to survive upright (freeing our hands), but the cost for many people is agonizing back pain. We are stuck with this barely adequate solution not because it is the best

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