House of War.

The Legacy of Jihad: Islamic Holy War and the Fate of Non-Muslims, edited by Andrew G. Bostom (Prometheus, 759 pp., $28)

HISTORIAN Robert Conquest recently pondered why so many of his fellow scholars had been for so long incapable of grasping the true nature of the Soviet regime. He concluded by blaming "a clerisy that has hardly heard of opinions other than those appearing to be . . . the acceptable expression of concern for humanity" and that has demonstrated "a strong tendency to silence those who disagree with one or another of the accepted beliefs."

As the fourth anniversary of the 9/11 attacks came and went, it was difficult not to experience a sense of deja vu. The failure of Western elites to acknowledge the totalitarian terror of the 20th century is eerily similar to their current failure to confront the Islamic totalitarian movements of the 21st. The same historical forces--and, in some cases, the very same individuals--are at work, not only trivializing accounts of the existential threat, but also legitimizing the enemy as political actors with rational grievances with whom one can treat on the basis of some ever-elusive common ground while condemning skeptics to political and academic obloquy.

Against this depressing backdrop, two welcome developments have recently taken place. The first was the acknowledgement by President Bush, in an October speech to the National Endowment for Democracy, that America is engaged in a struggle not only against terrorism the tactic, but also against the specific ideology that has inspired the most virulent manifestations of terrorism. "Some call this evil Islamic radicalism; others, militant Jihadism; still others Islamofascism," Bush said--and noted that this ideology is "very different from" Islam and, in fact, "exploits" it.

The second development is the publication of the new book The Legacy of Jihad, an impressive compendium that meticulously documents the terror that is jihad--using historical and contemporary Muslim theological and juridical texts, as well as the accounts of some of the most eminent Muslim and non-Muslim scholars of Islam in the days before political correctness squelched academic freedom.

The 750-page tome is by no means an easy read. It is a maze of primary texts and secondary studies, barely held together by the editor's lengthy but useful introduction. Perseverance, however, is rewarded: The wide-ranging anthology--including commentaries by representatives of Shiite as well as all four schools of Sunni jurisprudence, historical accounts of regional jihad campaigns, and analyses of current conflicts--takes the reader from the religious roots of the jihad ideology to the havoc that it has wrought across the continents of Asia, Africa, Europe, and, now, America.

Scholars of Islam will undoubtedly have criticisms, some of which may be justified. After all, the book's editor, Andrew G. Bostom, is not an academic specialist in Islam: He is a clinical epidemiologist on the faculty of Brown Medical School. But not being a card-carrying member of the contemporary academic fraternity of Middle East scholars gives Bostom the distinct advantage of being exempt from the shackles with which the field's regnant orthodoxies hobble many of his would-be competitors. Unburdened by the constraints of political correctness, Bostom provides an unparalleled documentary history of nearly 14 centuries of jihad, and of the non-Muslims who have been subjugated as a result of that relentless campaign. His account is a somber warning of the mortal challenge posed to free societies by the ongoing jihad of the militants.

Scholars as well as general readers owe a debt of gratitude to Bostom for making available a number of very important texts--including, for the first time in English, the commentaries on the Koran's ninth sura (the text on jihad) by al-Baydawi, al-Suyuti, al-Zamakhshari, al-Tabari, and al-Ghazali. But he won't be receiving many congratulatory messages from academia, which will feel the sting of the evidence he adduces against some of its cherished shibboleths--including what Bernard Lewis has called "the myth" of a "Golden Age of equal rights" in Islamic-ruled Spain.

Muslim scholars like UCLA law professor Khaled Abou El Fadl, author of a widely quoted post-9/11 text on moderate Islam, may be right that "Islamic tradition does not have a notion of holy war" and that jihad "simply means to strive hard or struggle in the pursuit of a just cause" (although Bostom unearths a 1999 article in which the same El Fadl asserted the contrary). And Koranic passages like the ninth sura may be misinterpreted by radicals. In time, perhaps, voices of reason within the Muslim community may prevail. For now, however, the widespread support that the terrorists have enjoyed throughout the Muslim world suggests that their jihad ideology represents a current that is not that far out of the historical mainstream. In any event, the logic of terrorism requires only a fanatical few to unleash destruction on the many.

If it is the destiny of the contemporary West to be tested in the forge of unrelenting jihadist warfare, then its defenders would do well to be armed with an understanding of the ideology that motivates its foes. The Legacy of Jihad is a very good place to start.

Mr. Pham is director of the Nelson Institute for International and Public Affairs at James Madison University and an academic fellow at the Foundation for the Defense of Democracies.