However, he is best remembered now as the originator of a variety of unorthodox theories, especially his opinion that a 14th Century conspiracy forged practically all literature traditionally believed to have been written before that era.

[1] Although Hardouin has been called "pathological" and "mad,"[2][3] he was only an extreme example of a general critical trend of his time, following authors like Baruch Spinoza, Thomas Hobbes or Jean Daillé, who had started to identify and discard mistaken attributions or datings of medieval documents or Church writings.

On the advice of Jean Garnier (1612–1681) he undertook to edit the Natural History of Pliny for the Dauphin series, a task which he completed in five years.

[5] Hardouin was appointed by the ecclesiastical authorities to supervise the Conciliorum collectio regia maxima (1715); but he was accused of suppressing important documents and including apocryphal ones, and by the order of the parlement of Paris (then in conflict with the Jesuits) the publication of the work was delayed.

[11] The most noteworthy work which appeared in the 1733 Opera varia was Hardouin's Athei detecti (The Atheists Exposed), in which the atheists in question were Cornelius Jansen, André Martin, Louis Thomassin, Nicolas Malebranche, Pasquier Quesnel, Antoine Arnauld, Pierre Nicole, Blaise Pascal, René Descartes, Antoine Le Grand, and Pierre-Sylvain Régis.

According to the Gospels, Jesus gave his disciple Simon son of Jonah a new name given in Aramaic and Greek versions as "Cephas" and "Peter.

[39][40] In 1707, Michel Le Tellier [fr] launched an investigation into Hardouin's system at the behest of the Jesuit Superior General, Michelangelo Tamburini.

Nearly a dozen Jesuits wrote to Tamburini, all opining that Hardouin's ideas were so dangerous to the Society of Jesus and the Catholic Church as to warrant their suppression.

[41] Maturin Veyssière La Croze, a Protestant author, assailed Hardouin's system in a work written in French,[42] and then another printed in Latin.

In February 1709, a "Declaration" appeared in the Mémoires pour l'Histoire des Sciences & des beaux-Arts (generally known as the Journal de Trévoux) signed by Le Tellier and the superiors of the Jesuit houses in Paris, and attesting to Tamburini's approval of the statement as well, in which they said that the Amsterdam edition contained works they wished had never seen the light of day or would fall into oblivion.

[52] Likewise, though Hardouin admitted the authenticity of Horace' Epistles and Satires, he composed a work purportedly demonstrating the spuriousness of the Odes, the Epodes, the Carmen saeculare, and the Ars poetica.

[54][55] Hardouin perceived anachronisms and heterodoxy in the Divine Comedy, which he believed had been falsely attributed to Dante Alighieri by its true author, a follower of John Wycliffe.

[58] In the 1713–4 Boyle Lectures, Benjamin Ibbot cited Hardouin's belief in the spuriousness of nearly all ancient literature as an example to demonstrate that the opinion of one prestigious author in the face of an otherwise universal consensus did not lend credibility to such patently absurd ideas.

[59] The historian Isaac-Joseph Berruyer had his Histoire du peuple de Dieu condemned for having followed this theory, which has a modern heir in the Russian mathematician Anatoly Timofeevich Fomenko, whose conclusions being based on proprietary methods of statistical textual analysis and computational astronomy are even more radical, but considered to be pseudoscientific.