Many of Vonnegut's recurring themes are prevalent in Cat's Cradle, most notably the issues of free will and man's relation to technology. The former is embodied in the creation of Bokononism, an artificial religion created to make life bearable to the beleaguered inhabitants of San Lorenzo through acceptance and delight in the inevitability of everything that happens. The latter is demonstrated by the development and exploitation of ice-nine, which is conceived with indifference but is misused to disastrous ends. In his 1969 address to the American Physical Society, Vonnegut describes the inspiration behind ice-nine and its creator as the type of "old-fashioned scientist who isn't interested in people," and draws connections to nuclear weapons.
More topically, Cat's Cradle takes the threat of nuclear destruction in the Cold War as a major theme. The Cuban Missile Crisis, in which world powers collided around a small Caribbean island, bringing the world to the brink of mutual assured destruction, occurred in 1962, and much of the novel can be seen as allegorical.