McGuire was different. In the first place, he was mobile. He was in command of a spacecraft. In a sense, he was the spacecraft, since it served him in a way that was analogous to the way a human body serves the human mind. And he wasn't in charge of millions of objects with a top velocity of a hundred and fifty miles an hour; he was in charge of a single object that moved at velocities of thousands of miles per second. Nor did he have a set, unmoving highway as his path; his paths were variable and led through the emptiness of space.
Unforeseen emergencies can happen at any time in space, most of them having to do with the lives of passengers. A cargo ship would be somewhat less susceptible to such emergencies if there were no humans aboard; it doesn't matter much to a robot if he has no air in his hull.
But with passengers aboard, there may be times when it would be necessary to give orders—fast! And that means verbal orders, orders that can be given anywhere in the ship and relayed immediately by microphone to the robot's brain. A man doesn't have time to run to a teletyper and type out orders when there's an emergency in space.
That meant that McGuire had to understand English, and, since there has to be feedback in communication, he had to be able to speak it as well.
And that made McGuire more than somewhat difficult to deal with.
For more than a century, robotocists have been trying to build Asimov's famous Three Laws of Robotics into a robot brain.
First Law: A robot shall not, either through action or inaction, allow harm to come to a human being.
Second Law: A robot shall obey the orders of a human being, except when such orders conflict with the First Law.