There was only one catch and that was Catch-22, which specified that a concern for one’s own safety in the face of dangers that were real and immediate was the process of a rational mind. Orr was crazy and could be grounded. All he had to do was ask; and as soon as he did, he would no longer be crazy and would have to fly more missions. Orr would be crazy to fly more missions and sane if he didn’t, but if he was sane he would have to fly them. If he flew them he was crazy and didn’t have to; but if he didn't want to he was sane and had to. Yossarian was moved very deeply by the absolute simplicity of this clause of Catch-22 and let out a respectful whistle. “That’s some catch, that Catch-22,” he observed. “It’s the best there is,” Doc Daneeka agreed.
This passage from Chapter 5 marks the novel’s first mention of the paradoxical law called “Catch-22.” Over the course of the novel, Catch-22 is described in a number of different ways that can be applied to a number of different aspects of wartime life; here, however, Catch-22 affects Yossarian most specifically. Catch-22 is alarmingly persuasive; even Yossarian accepts what seems to be its logical infallibility. But Catch-22 is an abstract thing; we find out later that Yossarian believes that Catch-22 does not really exist. It is a trap made up of words, and words are faulty things, often misrepresenting reality. What is so upsetting about the way Catch-22 is applied throughout the novel is that real men are sent into real peril based on a few unreal and unreliable words.