I thoroughly appreciate the conceit that documentary director Robert Kenner (Food, Inc.) uses to introduce his latest feature — Merchants of Doubt — which explores the flim-flam nature of public relations in the service of creating skepticism surrounding hot-button topics like tobacco and global warming. He posits that such underhanded efforts are similar to the chicanery of a magician or a street-corner con artist working a game with his shill, but we are warned by a practitioner of sleight of hand that his game in particular is different because he is “an honest liar,” meaning that his audience knows from the start that he’s going to trick them.

In addition, the stakes are much lower than, say, concerns about cancer or the survival of the planet. The “scientists” and public relations specialists who fought to persuade consumers against the dangers of smoking (supported by studies from the tobacco companies themselves) or who continue to stand in opposition to the overwhelming scientific evidence of man’s role in global warming practice something more insidious than mere dishonesty. Kenner’s film highlights not only the impact of their lies on those in pursuit of the truth, but also the willful (and downright gleeful) harm they cause to the reputations of those who have done nothing more than dedicate their lives to finding answers to real problems. The game is rigged, but once we see the strings being pulled, we can’t “unsee” them ever again. (PG-13) Grade: A-