Arnold is the chief engineer at the park, and he's Malcolm's foil. Arnold has his concerns about the park, but he fundamentally disagrees with Malcolm's theoretical objections to the project—and with Malcolm's theorizing in general. A small, nervous man, Arnold goofs big when trying to restore power to the park and reload the computer system. He should have trusted himself a little bit less and actually verified the success of his actions. Like a lot of the book's characters, he gets himself into trouble because he thinks he's in control when he really isn't.