As typical for a discussion of memes (of the Richard Dawkins variety), I'm about to talk about something completely unoriginal to me, but that I've modified to some degree after thinking about it.
The thesis is this: there's a tendency for people to have more interest in explaining the spread of ideas they think are false, when compared to ideas they think are true.
For instance, there's a lot written about how and why religion spread through the world. On the other hand, there's comparatively little written about how and why general relativity spread through the world. But this is strange -- they are both just ideas that are spread via regular communication channels.
One could say that the difference is that general relativity permits experimental verification, and therefore it's no surprise that it spread through the world. The standard story here is that since the idea is simply true, the explanation for why it became widespread is boring -- people merely became convinced due to its actual veracity.
I reject this line of thought for two reasons. First, the vast majority of people don't experimentally verify general relativity, or examine its philosophical basis. Therefore, the mechanism by which the theory spreads is probably fairly similar to religion. Secondly, I don't see why the idea being true makes the memetic history of the idea any less interesting.
I'm not really sure about the best explanation for this effect -- that people treat true memes as less interesting than false ones -- but I'd like to take a guess. It's possible that the human brain seeks simple single stories to explain phenomena, even if the real explanation for those phenomena are due to a large number of factors. Furthermore, humans are bored by reality: if something has a seemingly clear explanation, even if the speaker doesn't actually know the true explanation, it's nonetheless not very fun to speculate about.
This theory would predict that we would be less interested in explaining why true memes spread, because we already have a readily available story for that: namely, that the idea is true and therefore compels its listeners to believe in it. On the other hand, a false meme no longer permits this standard story, which forces us to search for an alternative, perhaps exciting, explanation.
One possible takeaway is that we are just extremely wrong about why some ideas spread through the world. It's hard enough to know why a single person believes what they do. The idea that a single story could adequately explain why everyone believes something is even more ludicrous.
I agree with your point that people frequently seem more interested in the spread of enemy ideas than their own. Only a lazy thinker would hold the opinion that bad ideas because of one cause. I saw a paper just yesterday detailing that advocates of religious terrorism tended to have at least some college. That research only just recently seems to have become mainstream. Why so? The causal mechanisms are not simple for single person.
On the other hand, for looking at a group, that doesn't mean the causal mechanism has to be MORE complicated. It might even be more simple. A single person can come to a belief for complex reasons, but perhaps the same belief can propagate through society for a simpler reason than the reason each individual comes to embracing it, such as, "it's included in every 9th grade textbook" or "it allows one to find a spouse more easily." Maybe this begs the question though? How did the idea get included in every textbook? Why does the idea allow one to find a spouse more easily?
Peter Adamson's History of Philosophy without Any Gaps does not discuss the history of how ideas have spread explicitly, but he does deal with the history of the interaction of major philosophical concepts and schools of thought. Beneath the content of the arguments is the story of the history of education, literacy, and evangelization. You pick up any history of Christianity, and it will still go into detail about how different tactics and strategies for the spread of the Christian idea: domestic proselytization, missionaries offering services to kings, centers of literacy, outreach to poor people, conversions of whole households, military force, etc. In some instances we even have the tactics recorded. The Jesuits sent thousands of letters to their superiors detailing their attempts to spread Christianity among Native Americans in the Great Lakes Region.
The Rationalsphere has not even begun to develop a method or programmatic approach to the spread of rationality.
It seems to me like the field of History and Philosophy of Science does look at why scientific ideas spread and they usually don't answer it with "the idea was simply true".
I has the impression that when people write about the history of science, they tend to write about who discovered what, and how, but very little about what happened to the idea afterwards. I don't expect to find many chapters of history of science titled, "How scientific theories are spread through the world" but it's trivial to find an equivalent chapter on religion, or say, communism.
I think I'd expect to find chapters like that even if the book was written by an adherent of the religion or of communism. If I'm right, that seems to somewhat point away from "if it's true, we don't feel the need to explain it".
Possible complicating factors there are belief-in-belief effects, the knowledge that other people don't believe the thing, and desire to evangelize.
I would theorize that in the brain there are parameters that determine how likely and to what effect that they will remember and spread the idea. Then in general populations these parameters fit general trends. So any idea could fit these parameters but false ideas are more malleable to fit the parameters and thus increasing their spread.
false ideas are more malleable to fit the parameters and thus increasing their spread.
1) Or if you create something that fits the parameters (esp. a lot of parameters) it's probably false. (Too widely popular.)
2) While something true may fit well, something false that takes the parts that fit well and turns them up to 11 fits better. (Too strongly popular.)