“A generation which ignores history has no past and no future.” - Robert Heinlein
To know history is to know the mistakes of those who came before us. To understand history is to know why those mistakes happened. Generally speaking, mistakes happen due to our nature.
The ignorance of history is the assumption of mankind's evolution beyond the mistakes made during the entirety of history, including events as recently as our youth. Are we vain enough to believe we can evolve that far in one generation? I would say yes.
How many people in the world deny the Holocaust took place? How many people believe in global warming, when 30 years ago it was supposed to be global cooling? How many Mexicans claim that America stole land from them, completely ignoring the fact the Spanish stole Mexico from the Aztecs?
I would not go so far as Heinlein and say we have no future. Though I will say our future is going to look a lot like our past.