What Adams later said is that he was inspired by a TV program about judo. From the program, he learned that if you have a problem, such as a nineteen-stone Japanese man in pajamas coming after you, you can turn that into a solution. If you can somehow trip or throw or deflect that man, the fact that he weighs nineteen stone quickly becomes his worry, rather than yours.

So, the problem Adams was having was that every solution he could come up with to the predicament of Ford and Arthur was wildly improbable. So what did he use to solve the problem? Improbability, in the form of the Infinite Improbability Drive, which gave him a whole new thing to write about.