Mostly Harmless [16]
The familiar H-shaped building of the Hitch Hiker's Guide offices rose above the outskirts of the city, and Ford Prefect had broken into it in the familiar way. He always entered via the ventilation system rather than the main lobby because the main lobby was patrolled by robots whose job it was to quiz incoming employees about their expense accounts. Ford Prefect's expense accounts were notoriously complex and difficult affairs and he had found, on the whole, that the lobby robots were ill-equipped to understand the arguments he wished to put forward in relation to them. He preferred, therefore, to make his entrance by another route.
This meant setting off nearly every alarm in the building, but not the one in the accounts department, which was the way that Ford preferred it.
He hunkered down behind the storage cabinet, he licked the rubber suction cup of the toy arrow, and then fitted it to the string of the bow.
Within about thirty seconds a security robot the size of a small melon came flying down the corridor at about waist height, scanning left and right for anything unusual as it did so.
With impeccable timing Ford shot the toy arrow across its path. The arrow flew across the corridor and stuck, wobbling, on the opposite wall. As it flew, the robot's sensors locked on to it instantly and the robot twisted through ninety degrees to follow it, see what the hell it was and where it was going.
This bought Ford one precious second, during which the robot was looking in the opposite direction from him. He hurled the towel over the flying robot and caught it.
Because of the various sensory protuberances with which the robot was festooned, it couldn't manoeuvre inside the towel, and it just twitched back and forth without being able to turn and face its captor.
Ford hauled it quickly towards him and pinned it down to the ground. It was beginning to whine pitifully. With one swift and practised movement, Ford reached under the towel with his No.3 gauge prising tool and flipped off the small plastic panel on top of the robot which gave access to its logic circuits.
Now logic is a wonderful thing but it has, as the processes of evolution discovered, certain drawbacks.
Anything that thinks logically can be fooled by something else which thinks at least as logically as it does. The easiest way to fool a completely logical robot is to feed it the same stimulus sequence over and over again so it gets locked in a loop. This was best demonstrated by the famous Herring Sandwich experiments conducted millennia ago at MISPWOSO (The MaxiMegalon Institute of Slowly and Painfully Working Out the Surprisingly Obvious).
A robot was programmed to believe that it liked herring sandwiches. This was actually the most difficult part of the whole experiment. Once the robot had been programmed to believe that it liked herring sandwiches, a herring sandwich was placed in front of it. Whereupon the robot thought to itself, "Ah! A herring sandwich! I like herring sandwiches."
It would then bend over and scoop up the herring sandwich in its herring sandwich scoop, and then straighten up again. Unfortunately for the robot, it was fashioned in such a way that the action of straightening up caused the herring sandwich to slip straight back off its herring sandwich scoop and fall on to the floor in front of the robot. Whereupon the robot thought to itself, "Ah! A herring sandwich..., etc., and repeated the same action over and over and over again. The only thing that prevented the herring sandwich from getting bored with the whole damn business and crawling off in search of other ways of passing the time was that the herring sandwich, being just