no one at all. Precisely," said Fastolfe, ignoring the irony. "The humaniform robots have brains - and, I might add, bodies - constructed in conscious imitation of the human being. The positronic brains are extraordinarily delicate and they take on some of the fragility of the human brain, naturally. Just as a human being may have a stroke, though some chance event within the brain - and without the intervention of any external effect, so a humaniform brain might, through chance alone the occasional aimless drifting of positrons - go into mental - "
"Can you prove that, Dr. Fastolfe?"
"I can demonstrate it mathematically, but of those who could follow the mathematics, not all would agree that the reasoning was valid. It involves certain suppositions of my own that do not fit into the accepted modes of thinking in robotics."
"And how likely is spontaneous mental freeze-out?"
"Given a large number of humaniform robots, say a hundred thousand, there is an even chance that one of them might undergo spontaneous mental freeze-out in an average Auroran lifetime. And yet it could happen much sooner, as it did to Jander, although then the odds would be very greatly against it."
"But look here, Dr. Fastolfe, even if you were to prove conclusively that a spontaneous mental freeze-out could take place in robots generally, that would not be the same as proving that such a thing happened to Jander in particular at this particular time."
"No," admitted Fastolfe, "you are quite right."
"You, the greatest expert in robotics, cannot prove it in the specific case of Jander."
"Again, you are quite right."
"Then what do you expect me to be able to do, when I know I nothing of robotics."
"There is no need to prove anything. It would surely be sufficient to present an ingenious suggestion that would make spontaneous mental freeze-out plausible to the general public."
"Such as - "
"I don't know."
Baley said harshly. "Are you sure you don't know, Dr. Fastolfe?"
"What do you mean? I have just said I don't know."
"Let me point out something. I assume that Aurorans, generally, know that I have come to the planet for the purpose of tackling this problem. It would be difficult to manage to get me here secretly, considering that I am an Earthman and this is Aurora."
"Yes, certainly, and I made no attempt to do that. I consulted the Chairman of the Legislature and persuaded him to grant me permission to bring you here. It is how I've managed to win a stay in judgment. You are to be given a chance to solve the mystery before I go on trial. I doubt that they'll give me a very long stay."
"I repeat, then - Aurorans, in general, know I'm here and I imagine they know precisely why I am here - that I am supposed to solve the puzzle of the death of Jander."
"Of course. What other reason could there be?"
"And from the time I boarded the ship that brought me here, you have kept me under close and constant guard because of the danger that your enemies might try to eliminate me judging me to be some sort of wonderman who just might solve the puzzle in such a way as to place you on the winning side, even though all the odds are against me."
"I fear that as a possibility, yes."
"And suppose someone who does not want to see the puzzle solved and you, Dr. Fastolfe, exonerated should actually succeed in killing me. Might that not swing sentiment in your favor? Might not people reason that your enemies felt you were, in actual fact, innocent or they would not fear the investigation so much that they would want to kill me?"
"Rather complicated reasoning, Mr. Baley. I suppose that, properly exploited your death might be used to such a purpose, but it's not going happen. You are being protected and you will not be killed."
"But why protect me, Dr. Fastolfe? Why not let them kill me and use my death as a way of winning?"
"Because I would rather you remained alive and succeeded in actually demonstrating my innocence."
Baley said, "But surely you know that I can't demonstrate your innocence."
"Perhaps you can. You have every incentive. The welfare of Earth hangs on your doing so and, as you have told me, your own career."
"What good is incentive? If you ordered me to fly by flapping my arms and told me further that if I failed, I would be promptly killed by slow torture and that Earth would be blown up