What does this mean? First, let's consider idaafa. Idaafa is a construction that expresses the possessive relationship between two nouns in Arabic. The other day I likened it to the German genitive, and the more I learn about idaafa, the more I think that this is a very good analogy. It is a very useful way to understand this idea, at least for those who have studied German. For example, das Buch des Vaters is a genitive construction in German. Arabic will have the exact same construction with kitab-u al-waalidi. Like anything in a German genitive construction, the idaafa must take genitive case endings. Tanween, meanwhile, is the concept of doubling the last vowel in a word. To have the nominative indefinite, you double the damma, which is equivalent to our short 'u', but if you have the tanween al-fatha (this phrase is itself idaafa) you double the fatha (equivalent to a short 'a'). This has the effect of making the noun accusative, and you cannot have a random accusative floating around in a genitive construction. At least, that's what I've managed to understand so far. Now admit it--you really wanted to know that.
If I haven't lost you yet and you have gone on to read this part, you should know that the rest of this post, like its predecessor, will be about something entirely different. A few years ago a book came out called Crossroads to Islam. To call it a revisionist history is to state the case too weakly. It would also tend to give revisionist history a very, very bad name. In the future, I will probably have more extended remarks about this book, but for the moment I will focus mainly on the book's claims about Byzantine religious policy, as that is my main interest in the book.
Crossroads to Islam has many controversial interpretations of early Islam and 6th and 7th century Byzantium. In fact, to call them controversial once again fails to capture how bizarre they are. One of the its principal claims is that Islam as anything like the distinctive monotheistic religion that it was later did not exist in the seventh century in any way. This is not just a claim that Islam developed over time or borrowed heavily from Jewish and Christian sources, both of which are familiar and more or less defensible arguments. The book's claim is that Muhammad never existed, the entire tradition about him was invented substantially later, at the end of the seventh century under Caliph Abd al-Malik, and that Islam as its own religion is a product of the eighth and ninth centuries. Again, this is not merely a claim that Christians initially believed Islam to be a new Christian heresy (which they did), but that everything distinctive about Islam was only created much later. Oh, yes, and Mu'awiya was the first caliph. All of this allegedly comes from rock inscriptions, archaeological research and recourse to "contemporary sources." However, "contemporary sources" on the Muslim side are essentially non-existent as far as literary records go, and on the Byzantine side every piece of evidence suggests that this revisionism is dead wrong.
I trust that there are Islamicists more competent than I am in early Islamic history who have and will continue to make the necessary arguments to refute these claims. The claims about Byzantine policy are equally odd, if less inherently offensive to hundreds of millions of people, and they are no more defensible. The main claim is that Byzantine religious policy from the late sixth century onwards was a deliberate effort to alienate the Near Eastern, non-Chalcedonian populations of the empire with increasingly confrontational religious policies. I am certainly sympathetic to revision of Byzantine religious history, but this is ridiculous. Besides being based mainly on conjecture derived from secondary sources, such as Aziz Atiya's History of Eastern Christianity, most of which are not even the standard references for Byzantinists, the evidence for a planned Byzantine withdrawal from some of its richest territories is that the Byzantines used the Ghassanids as foederati. This supposedly proves that the Byzantines were giving up on the Near East, even though most of their subjects and tax revenues came from the provinces they were apparently in a hurry to cast off.
There are obvious reasons why this is completely unpersuasive. States are not in the business of hiving off their richest territories and actively pursuing policies that they know and hope will cause their subjects to welcome the end of their rule. States may be indifferent to their subjects' attitudes towards the rulers, but they are definitely not indifferent to a decline in revenues and power. On the religious side, without giving away too much of my dissertation, I will simply say that the authors of Crossroads to Islam do not understand some of the most basic theological questions involved in the religious disputes of the sixth and seventh century in the Christian Near East. They say, for instance, that the "result of the religious policy which Byzantium pursued during these crucial years was to remove the remaining vestiges of Chalcedonianism from the eastern provinces, by unifying both churches, Orthodox and Monophysite, in acceptance of a non-Chalcedonian position." (p. 61) This would be interesting, if there were any truth to it. The problem with monotheletism was not that it was non-Chalcedonian, but that it was Chalcedonian while also trying to sound ever-more extremely Cyrilline. Chalcedonianism did not cease to exist in the eastern provinces, but split into two factions over this very question, while the non-Chalcedonians went on their merry way, being largely quite indifferent to a dispute between "Synodites." There are additional problems with the book's treatment of monotheletism (and virtually everything else), but this gives a basic sense of the kind of mistakes that the authors make.