Vulcan’s Hammer by Philip K. Dick

After the twentieth century’s devastating series of wars, the world’s governments banded together into one globe-spanning entity, committed to peace at all costs. Ensuring that peace is the Vulcan supercomputer, responsible for all major decisions. But some people don’t like being taken out of the equation. And others resent the idea that the Vulcan is taking the place of God. As the world grows ever closer to all-out war, one functionary frantically tries to prevent it. But the Vulcan computer has its own plans, plans that might not include humanity at all.