I came across this word while browsing and could not browse its definition. I understand amnesia, have heard of retrograde amnesia,but cultural amnesia appears jarring to my mind.
The expression "cultural amnesia" would likely come from the lips of someone who bemoans the tendency of some people to forget about their roots, particularly the values, customs, mores, taboos, and ideals which may have once been embraced by a people-group as a whole but have now been forgotten and replaced by different customs, mores, taboos, and ideals.
Generally speaking (i.e., painting with a very broad brush), conservatives are more likely to miss the "good old days." On the other hand, liberals are more likely to embrace change, pointing out that the "good old days" were not necessarily that good, just old! To them, it's time to get with it, to go with the flow, and so on.
This is not to say that liberals might not say the same thing, particularly if they are appealing to an ideal or value which was once embraced by the culture but has since fallen by the wayside and now needs to be revivified and embraced.
Either way, whether from the mouth of a liberal or a conservative, cultural amnesia has a negative connotation, and could be a rallying cry of someone who claims the culture at large is missing something important.
By the way, the simplest and best definition of culture I've ever come across:
Culture is the way we do things around here.
Cultural amnesia, then, would be revealed in a widespread ignorance of what used to be important but has now fallen into desuetude.
It does prove to be surprisingly hard to Google. In general, my sense is that it primarily means social amnesia, the collective, often deliberate forgetting of something important by a group, with additional connotations of both a culture of amnesia (meaning a culture that represses memories), and the forgetting or abandonment of things of specific cultural importance (long held social values, for example).
It is hard to guess the author's intent without seeing the context, but I would assume it is referring to the failure of a society or group of people to remember important aspects of their history, or a willingness to pretend that their cultural history is other than it is.
I think it is related to the repeated mistakes during the human history. We should learn from these mistakes, trying not to do it again, but it doesn't happen. However there's this book from Clive James with the same name. It's about ''destroying'' the conception we have about notable people '' to burnish these memories of a Western civilization that James fears is nearly lost'' (from goodreads).