Book excerpt: Denying History takes a bold and in-depth look at those who say the Holocaust never happened and explores the motivations behind such claims. While most commentators have dismissed the Holocaust deniers as antisemitic neo-Nazi thugs who do not deserve a response, historians Michael Shermer and Alex Grobman have immersed themselves in the minds and culture of these Holocaust "revisionists." In the process, they show how we can be certain that the Holocaust happened and, for that matter, how we can confirm any historical event. This edition is expanded with a new chapter and epilogue examining current, shockingly mainstream revisionism.