It wasn't the big countries that set off this thing. It was the little ones, the Irresponsibles.
  

John makes this comment in Chapter Three when he is discussing the cause of the war with Dwight and Peter. With this one statement, Shute quietly shows that a nuclear war is possible. Optimists argue that humans are too rational to destroy themselves; Shute agrees that collectively people are rational, but believes that nuclear weapons can fall into hands of irrational minority. In the war that precedes the events of the novel, a nuclear bomb falls on Tel Aviv without any a answer of who dropped it or why. When bombs begin to drop in other countries, the response to send retaliatory bombs seemed rational to the military reasoning of the time. Shute's argument is that it is not rational to have bombs in the first place. Some critics have found fault with Shute's blaming the war on small countries and taking the blame away from the larger countries. Regardless, Shute's warning about the dangers of nuclear proliferation is a striking one, and was even more so at the time of the novel's publication, in the midst of the tensions of the Cold War.