Truth to Post-Truth in American Detective Fiction examines questions of truth and relativism, turning to detectives, both real and imagined, from Poe’s C. Auguste Dupin to Robert Mueller, to establish an oblique history of the path from a world where not believing in truth was unthinkable to the present, where it is common to believe that objective truth is a remnant of a simpler, more naïve time. Examining detective stories both literary and popular including hard-boiled, postmodern, and twenty-first century novels, the book establishes that examining detective fiction allows for a unique view of this progression to post-truth since the detective’s ultimate job is to take the reader from doubt to belief. David Riddle Watson shows that objectivity is intersubjectivity, arguing that the belief in multiple worlds is ultimately what sustains the illusion of relativism.