The third of the devil’s tricks is historicism. In Fides et Ratio Pope John Paul II teaches, “the fundamental claim of historicism is that the truth of a philosophy is determined on the basis of its appropriateness to a certain period and a certain historical purpose. At least implicitly therefore, the enduring validity of truth is denied. What was true in one period, historicists claim, may not be true in another.“

Historicism is stated in popular terms as a disdain for anything that comes from a previous time period, and along with this is the assumption that ‘new is better’ and that what we know now must be more advanced than what they knew long ago. So the Middle Ages are referred to as ‘the Dark Ages.’ Historicism is usually mixed up with sentimentality in the popular media. So along with the assumption that the Middle Ages (or any previous age) is backward, ignorant and benighted, goes a popular mental image of this awful age. Thus the people of the Middle Ages are pictured as deformed, stunted, ugly, smelly, diseased, superstitious and ignorant. Likewise people from any previous age. They are all pictured as only slightly more advanced than Neanderthal man.
The sentimental historicist never stops to realize that while there were certainly ignorant, diseased and brutish people in the Middle Ages, that our own society is riddle with equally poor specimens of humanity, and conversely, just as we have some bright, good looking and wonderful people, so did previous ages.
Historicism, therefore holds hands with its sister: Progressivism. Progressivism is historicism run riot. This is the logical conclusion from historicism: the belief that “every day in every way we’re getting better and better.” While this may be true on the technological front it patently not true on the spiritual, intellectual and moral front. 
Finally, in the nightmare scenario the progressivist holds hands with the utilitarian and the join forces to usher in what they consider to be a ‘brave new world’. Believing that humanity (and mostly themselves) can only be getting better and better every day, and believing that what is best is what works they bring about the most monstrous tyranny, slaughter, bloodshed, injustice of every kind and ultimately genocide.
And they do all this thinking they are doing the very best for humanity