Susan Jacoby's Freethinkers is an important, essential work of American history that's unfortunately married to a naively unproblematic (and thus very American) concept of Enlightenment rationalism. First the good news: the great value of this book lies in Jacoby's recovery of the forgotten and suppressed history of the American secular ideal and its champions, such almost entirely unknown figures as the early American radical freethinker Elihu Palmer, the orator Ernestine L. Rose (whom Jacoby calls "the Emma Goldman of the 1840s and 1850s"), and the famed "Great Agnostic" Robert G. Ingersoll. Ingersoll (1833-1899) was a household name in late 19th-century America, an influential Republican orator and outspoken opponent of organized religion whose public appearances drew large crowds (comparable to those drawn by his ideological opposites, the crusading evangelists). The fact that he is virtually unknown today says much about the troubling marginalization of religious dissenters in the official narrative of American history after about 1750. Jacoby's work thus does the best thing history writing can do: it rescues people from the footnotes and lacunae of traditional history and moves them into the center of a new and more complex version of the American story. It's a marvelous work.
My one serious reservation is directed toward the book's ideological underpinnings rather than it's wonderfully informative surface content. Jacoby's concept of the Enlightenment (which is also that of most American humanists, rationalists, secularists, etc.), owes much to the writings of Paine and Jefferson but seems innocent of the subsequent non-theological critical discourse of Enlightenment. Adorno and Horkheimer's idea that Enlightenment is inextricably entangled in domination or John Ralston Saul's more accessible critique of amoral technocracy in Voltaire's Bastards are just two nonreligious critical viewpoints that might have deepened Jacoby's book had she taken them into account. (I'm guessing that she considered these matters outside the scope of her work.)