On Sept. 11, 2001, Andrew Bostom, an academic research physician at Rhode Island Hospital, did what many outraged and shocked Americans did. On his way home from work, he stopped at a bookstore and bought a book about Islam.

As he recalls, it was something by Karen Armstrong, who, he didn't know at the time, is famous -- infamous -- for being a serial apologist for Islam. Reading parts of the book aloud that same night to his wife, also an academic, as they went about accounting for friends and family in their native New York City, he found the book "treacley" and superficial, lacking not only the scholarly heft he was used to in scientific research, but also a connection to unfolding events. Even a more extensive survey of readily available works on Islam yielded similar platitudes rooted less in Islamic theology and history than in the contemporary political dictates of multiculturalism. The scientist in him wanted to know more.

Thus marked the unexpected beginning of a rigorous and illuminating academic odyssey deep into the study of Islam -- "this depressing obsession of mine," as Bostom calls it. It has also acquainted the medical researcher with a global fraternity of Islamic scholars, which includes the two he calls his mentors: the Egyptian-born historian of dhimmitude, Bat Ye'or, and the Pakistani-born scholar of Islam and the West, Ibn Warraq.

So far, his studies have resulted in two meticulously researched and trail-blazing tomes of his own: "The Legacy of Jihad," published in 2005, and "The Legacy of Islamic Antisemitism," which has just come out, garnering enthusiastic advance comment from academics ("a ground breaking event" said Steven T. Katz, director of the Elie Wiesel Center for Judaic Studies, Boston University), historians ("It is magnificent," said Martin Gilbert, official biographer of Winston Churchill), and experts ("One of the most important books of our time," said Ayaan Hirsi Ali, author, "Infidel").

The obvious question is: How does a medical researcher studying homocysteine's effect on cardiovascular disease in patients suffering from chronic kidney problems shift his focus to the study of jihad and anti-Semitism in Islam?

Answer: He doesn't. That is, while embarked on his Islamic studies, Bostom -- a lifelong Democrat, by the way -- has remained the Principle Investigator in a $40 million, decade-long National Institutes of Health renal study involving more than 4,000 patients in the United States, Canada and Brazil. Not only that (and this is something that has impressed me, both as what you might call a confrere in Islamic inquiry and also as a friend), he has applied essentially the same scientific principles he uses in medical research to the study of Islam.

"We are used to analyzing things very critically and taking almost everything with a grain of salt," Bostom explained recently, discussing his work as a medical researcher at Rhode Island Hospital, the major teaching hospital affiliated with Brown University. Such analysis includes, for example, monthly gatherings known as morbidity and mortality reviews where errors and oversights in medical treatment are critically examined. "We are trained to think the stakes are never higher because we are dealing with life and death. If you get something wrong, you kill people."

Bringing such skepticism and urgency to the study of Islam (where, he maintains, "getting something wrong" can kill even more people), Bostom soon found himself butting up against consensus teachings contradicted by the voluminous evidence he was gathering. Take anti-Semitism in Islam, the subject of his new book. The view that Islamic anti-Semitism is a relatively recent import into Islam from Christian Europe and Nazi Germany is declared as settled fact by historians such as Bernard Lewis and popular authors such as Lawrence Wright ("The Looming Tower"). Bostom's conclusions, based on an array of religious texts and commentaries, historical analyses and eyewitness accounts, which he presents in "The Legacy of Islamic Antisemitism," suggest otherwise.

Both the anti-Semitism book and the jihad book before it are constructed similarly. They open with long introductory essays by Bostom, comparable, he says, to scientific grant proposals. In these essays, he presents his hypothesis based on his interpretation of the evidence and data reproduced in the rest of the book. In both books, such "raw material" includes key works from both Muslim and non-Muslim sources that have never before been translated into English. Such materials serve "as a reality check," Bostom says, "for people to read for themselves" in order to test his hypothesis.

After all, in history, as in science, the truth lies in the evidence.