"The President and his cabinet," Stafford offered tensely. "An ultimate decision like this has to be his. He bears the moral responsibility."

"But the decision," the engineer spoke up, "is not a moral question, Stafford. It only looks like it is. Actually the question is only a technical one. Is Genux-B working properly or has it broken down?"

And that's why you rousted me from bed, Stafford realized with a thrill of icy dismal grief. You didn't bring me here to implement your jerry-built jamming of the computer. Genux-B could be neutralized by one shell from one rocket launcher towed up and parked outside the building. In fact, he realized, in all probability it's effectively neutralized now. You can keep that Phillips screwdriver wedged in there forever. And you helped design and build the thing. No, he realized, that's not it. I'm not here to repair or destroy; I'm here to decide. Because I've been physically close to Genux-B for fifteen years – it's supposed to confer some mystic intuitive ability on me to sense whether the thing is functioning or malfunctioning. I'm supposed to hear the difference, like a good garage mechanic who can tell merely by listening to a turbine engine whether it has bearing knock or not, and if so how bad.

A diagnosis, he realized. That's all you want. This is a consultation of computer doctors – and one repairman.

The decision evidently lay with the repairman, because the others had given up.

He wondered how much time he had. Probably very little. Because if the computer were correct -

Sidewalk gum machines, he pondered. Penny-operated. For kids. And for that it's willing to pacify all Northern California. What could it possibly have extrapolated? What, looking ahead, did Genux-B see?

It amazed him: the power of one small tool to halt the workings of a mammoth constellation of autonomic processes. But the Phillips screwdriver had been inserted expertly.

"What we must try," Stafford said, "is introduction of calculated, experimental – and false – data." He seated himself at one of the typewriters wired directly to the computer. "Let's start off with this," he said, and began to type.

HERB SOUSA, OF SACRAMENTO, CALIFORNIA, THE GUM MACHINE MAGNATE, DIED SUDDENLY IN HIS SLEEP. A LOCAL DYNASTY HAS COME TO AN UNANTICIPATED END.

Amused, one of the FBI men said, "You think it'll believe that?"

"It always believes its data," Stafford said. "It has no other source to rely on."

"But if the data conflict," the engineer pointed out, "it'll analyze everything out and accept the most probable chain."

"In this case," Stafford said, "nothing will conflict with this datum because this is all Genux-B is going to receive." He fed the punched card to Genux-B then, and stood waiting. "Tap the outgoing signal," he instructed the engineer. "Watch to see if it cuts off."

One of the FBI men said, "We already have a line splice, so that ought to be easy to do." He glanced at the engineer, who nodded.

Ten minutes later the engineer, now wearing headphones, said, "No change. The Red Alert is still being emitted; that didn't affect it."

"Then it has nothing to do with Herb Sousa as such," Stafford said, pondering. "Or else he's done it – whatever it is – already. Anyhow, his death means nothing to Genux-B. We'll have to look somewhere else." Again seating himself at the typewriter, he began on his second spurious fact.

IT HAS BEEN LEARNED, ON THE ADVICE OF RELIABLE SOURCES IN BANKING AND FINANCIAL CIRCLES IN NORTHERN CALIFORNIA, THAT THE CHEWING GUM EMPIRE OF THE LATE HERB SOUSA WILL BE BROKEN UP TO PAY OUTSTANDING DEBTS. ASKED WHAT WOULD BE DONE WITH THE GUM AND TRINKETS CONSTITUTING THE GOODIES WITHIN EACH MACHINE, LAW-ENFORCEMENT OFFICERS HAZARDED THE GUESS THAT THEY WOULD BE DESTROYED AS SOON AS A COURT ORDER, NOW BEING SOUGHT BY THE ASSISTANT DISTRICT ATTORNEY OF SACRAMENTO, CAN BE PUT INTO EFFECT.

Ceasing typing, he sat back, waiting. No more Herb Sousa, he said to himself, and no more merchandise. What does that leave? Nothing. The man and his commodities, at least as far as Genux-B was concerned, no longer existed.

Time passed; the engineer continued to monitor the output signal of the computer. At last, resignedly, he shook his head. "No change."

"I have one more spurious datum I want to feed it," Stafford said. Again he put a card in the typewriter and began to punch.

IT APPEARS NOW THAT THERE NEVER WAS AN INDIVIDUAL NAMED HERBERT SOUSA; NOR DID THIS MYTHOLOGICAL PERSON EVER GO INTO THE PENNY GUM MACHINE BUSINESS.

As he rose to his feet, Stafford said, "That should cancel out everything Genux-B knows or ever did know about Sousa and his penny-ante operation." As far as the computer was concerned, the man had been retroactively expunged.

In which case, how could the computer initiate war against a man who had never existed, who operated a marginal concession which also never existed?

A few moments later the engineer, tensely monitoring the output signal of Genux-B, said, "Now there's been a change." He studied his oscilloscope, then accepted the reel of tape being voided by the computer and began a close inspection of that, too.

For a time he remained silent, intent on the job of reading the tape; then all at once he glanced up and grinned humorously at the rest of them.

He said, "It says that the datum is a lie."

IV

"A lie!" Stafford said unbelievingly.

The engineer said, "It's discarded the last datum on the grounds that it can't be true. It contradicts what it knows to be valid. In other words, it still knows that Herb Sousa exists. Don't ask me how it knows this; probably it's an evaluation from wide-spectrum data over an extensive period of time." He hesitated, then said, "Obviously, it knows more about Herb Sousa then we do."

"It knows, anyhow, that there is such a person," Stafford conceded. He felt nettled. Often in the past Genux-B had spotted contradictory or inaccurate data and had expelled them. But it had never mattered this much before.

He wondered, then, what prior, unassailable body of data existed within the memory-cells of Genux-B against which it had compared his spurious assertion of Sousa's nonexistence.

"What it must be doing," he said to the engineer, "is to go on the assumption if if X is true, that Sousa never existed, then Y must be true – whatever 'Y' is. But Y remains untrue. I wish we knew which of all its millions of data units Y is."

They were back to their original problem: Who was Herb Sousa and what had he done to alert Genux-B into such violent sine qua non activity?

"Ask it," the engineer said to him.

"Ask what?" He was puzzled.

"Instruct it to produce its stored data inventory on Herb Sousa. All of it." The engineer kept his voice deliberately patient. "God knows what it's sitting on. And once we get it, let's look it over and see if we can spot what it spotted."

Typing the proper requisition, Stafford fed the card to Genux-B.

"It reminds me," one of the FBI men said reflectively, "of a philosophy course I took at U.C.L.A. There used to be an ontological argument to prove the existence of God. You imagine what He would be like, if He existed: omnipotent, omnipresent, omniscient, immortal, plus being capable of infinite justice and mercy."

"So?" the engineer said irritably.

"Then, when you've imagined Him possessing all those ultimate qualities, you notice that He lacks one quality. A minor one – a quality which every germ and stone and piece of trash by the freeway possesses. Existence. So you say: If He has all those others, He must possess the attribute of being real. If a stone can do it, obviously He can." He added, "It's a discarded theory; they knocked it down back in the Middle Ages. But" – he shrugged – "it's interesting."