If one human being says "jump left," and another says "jump right," the robot is unable to evaluate which human being has given the more valid order. Feed enough confusing and conflicting data into a robot brain, and it can begin behaving in ways that, in a human being, would be called paranoia or schizophrenia or catatonia or what-have-you, depending on the symptoms. And an insane robot is fully as dangerous as an insane human being controlling the same mechanical equipment, if not more so. So the seventh model had been modified. The present McGuire's brain was impressed with slight modifications of the First and Second Laws. If it is difficult to define a human being, it is much more difficult to define a _responsible_ human being. One, in other words, who can be relied upon to give wise and proper orders to a robot, who can be relied upon not to drive the robot insane. The robotocists at Viking Spacecraft had decided to take another tack. "Very well," they'd said, "if we can't define all the members of a group, we can certainly define an individual. We'll pick one responsible person and build McGuire so that he will take orders only from that person." As it turned out, I was that person. Just substitute "Daniel Oak" for "human being" in the First and Second Laws, and you'll see how important I was to a certain spaceship named McGuire. * * * * * When I finally caught the beam from Ceres and set my flitterboat down on the huge landing field that had been carved from the nickel-iron of the asteroid with a focused sun beam, I was itchy with my own perspiration and groggy tired. I don't like riding in flitterboats, sitting on a bucket seat, astride the drive tube, like a witch on a broomstick, with nothing but a near-invisible transite hull between me and the stars, all cooped up in a vac suit. Unlike driving a car, you can't pull a flitterboat over and take a nap; you have to wait until you hit the next beacon station. Ceres, the biggest rock in the Belt, is a lot more than just a beacon station. Like Eros and a few others, it's a city in its own right. And except for the Government Reservation, Viking Spacecraft owned Ceres, lock, stock, and mining rights. Part of the reason for Viking's troubles was envy of that ownership. There were other companies in the Belt that would like to get their hands on that plum, and there were those who were doing everything short of cutting throats to get it. The PSD was afraid it might come to that, too, before very long. Ceres is fifty-eight million cubic miles of nickel-iron, but nobody would cut her up for that. Nickel-iron is almost exactly as cheap as dirt on Earth, and, considering shipping costs, Earth soil costs a great deal more than nickel-iron in the Belt.