What causes Dark Ages?

(Original post by Captain Haddock)
There was never a 'Dark Age'. Though it was once a fashionable view, it's ludicrous to write off the ~800 or so years between the fall of Rome and the Italian Renaissance as a period of decline, stagnation and ignorance. For that matter, I also take issue with the term 'Renaissance', as there was never any definable point of 'rebirth', as the name implies; instead there was a continuation of developments that had been taking place throughout the Middle Ages. Certainly few people at the time believed they were living through a golden age. Quite the opposite, in fact. Many contemporary authors wrote of an 'age of iron' - a time of great hardship and struggle. This was, after all, a period of extreme violence and (perceived or actual) social decline. Many of the stereotypical aspects of the 'Dark Ages' - tyrannical kings, bloody wars, witch hunts and persecution - actually intensified in the early modern period. In fact, if there was ever a 'Rennaisance', it would probably be fairer to say it took place during the 12th Century, in the midst of the 'Dark Ages'. This is where we see the appearance of our first European universities, the rise of the town, a boom in industry and trade, the translation of ancient Greek works into Latin via Arabic, huge advances in architecture, the rise of centralised bureaucratic states, and the birth of scholasticism together with a new emphasis on logic and reason. If Western Civilisation had a birthday, it would be somewhere in the 12th century.