Until the advent of materialism and 19th c. dogma, Western Civilisation was superior to anything Islam had developed. Islam has not aided in the development of the modern world; in fact civilisation has only been created in spite of Islam. Proof of this resides in the 'modern' world and the unending political-economic and spiritual poverty of Muslim states and regions. Squatting on richer civilisations is not 'progress'. Islam is pagan, totalitarian, and irrational.
Tyerman is a pretty good and reasonably stable medieval historian. Like Michael Wood the populist historian, Tyerman attempts to link history with real life; real people; real events. He doesn't indulge in the usual revisionist claptrap so beloved by academic trivia – at least not as much as some of his a-historical friends. In a chapter within a new book, 'The Medieval World' updated from its 2001 edition, he attempts to locate the Crusades in the time, place and space of the medieval world. It is not a bad attempt, but misses the main point.
The Crusades to recapture Jerusalem would never have occurred without Islam. It was the Moslem cult of Muhammad, whom Tyerman incorrectly states is not a god in Islam [Muhammad is most certainly a replacement for Christ and is linked throughout the Koran with Hub'Al the moon deity or Allah]; which devastated, raped, enslaved, butchered, eradicated and throttled Christianity from it birthplace to southern France, Moscow, Kyiv, Poland, and even Iceland. It took Christians 400 years to fight back. Ignoring the Moslem causation of the Crusades [7 in total]; is about as intelligent as stating that there is no causal force to motion within nature; or that a reaction occurred independently of a first action. It is bizarre and yet so depressingly common.
Tyerman's chapter in this book does not mention the Moslem Jihad once. Weird, but in an age of Orwellian language, fantasy as fact, and fiction as truth; it is unsurprising. Whilst some of his analysis is just and premised on some variety of empirical evidence, evading the topic of Islam and why the Crusades had to occur if civilization was to survive and the modern world to develop, is to put it mildly, stupid. But that is academia and trivia for you. The fetish today is that Islam, a bronze age barbarism which equates Muhammad with a moon idol 'god', and which has murdered some 150 millions in 1400 years of Jihad is 'good'. Christianity which created science, mathematics, technology, the agricultural and early industrial revolutions, universities, public schools and hospitals and a true moral-ethical code is 'bad'. Nice.