For a long time, people used to think that the brain was a rather simple organ. Apart from the bits that control the body machinery, there seemed to be a vast empty space in the young child's mind destined to be filled with whatever education, culture and personal experience provided. This view of the mind was never too plausible, since after all the liver and the gut are much more complex than that. But we did not know much about the way minds develop, so there were no facts to get in the way of this fantasy of a "blank slate" where experience could leave its imprint. The mind was like those vast expanses of unexplored Africa that old maps used to fill with palm trees and crocodiles. Now we know more about minds. We do not know everything, but one fact is clear: the more we discover about how minds work, the less we believe in this notion of a blank slate. Every further discovery in cognitive science makes it less plausible as an explanation. (3)
Back to Pascal Boyer's Religion Explained . . . then above passage from quite early on in the book.
This a pretty bad start on things. For one thing, Boyer is immediately sallying forth into an area that really doesn't have much to do with his topic. The history of attitudes toward human nature is just not fundamental to the topic of what religion is. He might just start by saying something like "The explanations put forward in this book assume that the human brain is an evolved entity, with certain inherent tendencies which . . ."
Instead we get the Blank Slate straw man. Why straw man? Because the man who proposed the idea, back in 1690, didn't think human beings had no inherent nature. he thought they had no inherent ideas. Durkheim, another supposed "blank slate" proponent specifically rejects the idea. And of course, before 1690, Western thought was dominated by precisely the opposite sorts of notions--that certain ideas were innate, that man had a fallen nature from birth, etc., etc.
So for a long time, since the beginning of the time we began thinking about what the nature of our minds or souls or brains was, the question has been dominated by the notion that in has a fairly specific nature, not by the fantasy of a "blank slate." In fact, this line of inquiry has been pretty heavily distorted by interested assertions as to what that specific nature is.
What Boyer really means to say here is that, for a few decades, the idea has been prevalent in anthropological circles that the contents of our brains are determined by our cultures, not by any inherent characteristics and that he and his book are part of the reaction against that prevalent notion.
There is nothing world-historically innovative in the idea that our brains have an inherent nature. This is the dominant line of thinking on this matter generally. It always has been.
The fantasy of a blank slate is today far less common that the fantasy of its absolute dominance in recent thought.
So why begin the book with the idea of some "Blank Slate" demon at large in the intellectual streets? Because what we are about to read will only impress when set against a backdrop of the most abject ignorance? ("Well, this is all pretty commonplace, but at least it is better than what those veritable flat-earthers think over there . . .)
Or maybe it's just a declaration of allegiance with the contemporary forces of expansionist science? Or maybe its just a failure of perspective from someone who has spent too much time in academic infighting. Or too much time in France.
I think the answer is probably one of the latter options, but nevertheless, it's a bad start to a book that as least pretends at a broad and objective attempt to explain religion.