[mkishi]

It probably doesn't, but I think "to propagate" is easily deemed an active engagement as opposed to a passive one. eg. while one can propagate an idea by doing nothing but waiting for people to come to them, I'd expect most people to assume "let's propagate this new idea" to mean a more active role in disseminating it — even if not quite directly reaching out to people.

[j4yav]

Would you assume some particular method of transfer was in play if someone said “the idea propagated out from the capital city”? To me it could be any number of ways, but in the end it spread out. It sounds like some people take this usage to mean the only possibility is that people from the capital city must have been going out and evangelizing it actively, not that people were visiting the capital and hearing it or something.

[Nition]

> It sounds like some people...

I'd be that person. "Propagate" strongly implies a push model to me; parent-to-child reproduction like an organism.

[Talanes]

I've always read it as a purposeful lack of describing effect. A word used when you don't want to address the "how" question, just that the spread happened.

[j4yav]

Exactly, I think that’s a better way to describe it. “Propagation occurred from inside out, rather than outside in” is talking about a state changing over time, but saying nothing about how that happened.

[inopinatus]

That isn't how organisms reproduce, either.

[mkishi]

I was actually careful not to equate "active" with "directly reaching out to people," but taking any active means of furthering the spread of the idea.

And, yes, I'd personally consider word-of-mouth to be largely push-based. But I concede it could just as well be people asking (perhaps too many) questions.