The irony of anti-conspiracy
The novel suggests that perhaps the true conspiracy was to stage an assassination to blame the Communists in Cuba to start a war with them. The theory is far-fetched and ironic, given the typical approach to the issue of conspiracy. Specifically, most people speculate that the original conspiracy was an attempt on Kennedy's life, but this theory holds that the CIA intentionally put him in harms way, intending the shot to miss.
Oswald's normal life
Lee Harvey Oswald's character in this book has regular opinions about much of life, and his time is spent being mostly normal, it seems. This is a long shot from what most people have made him out to be. This novel doesn't show Oswald as a wicked criminal mastermind. The most ironic aspect of the novel is that Oswald is described as a normal person, basically.
The irony of disenfranchisement
The plot suggests that perhaps Oswald's willingness to help in the CIA conspiracy might have been tied to his chronic disenfranchisement as a veteran of the Marine Corp, having married a Russian and sided with the Communists. He is ironically persecuted for these decisions, and his feeling of social disenfranchisement plays an ironic role in his willingness to execute the president, because he feels marginalized by the country. They picked the wrong person to "miss the shot."
The layers of normal life
The novel shows that the same conspiracy theory approach that many take when attempting to understand Kennedy's assassination—it can be used to analyze regular life. This ironic complexity and interconnectedness is explored through DeLillo's wandering associative prose, and it is demonstrated in the interconnectedness of the plot's minor characters. The novel itself could be read through an analytical lens.
The irony of fate
If the premise of conspiracy theories is that surely, coincidence cannot be so strange and timely as real life is, then the irony of fate is that, actually, real life seems to follow a strangely fateful plot. The novel explores this by disarming various conspiracy theories and by suggesting that actually, it could be regular old normal life that brought Oswald to his unimaginable fate. It could also be regular life that brought Kennedy to his untimely demise. Why? Because of the unexplainable nature of human fate.
