I don't have a name for this. A person can make a statement "X", and X can be true, but the person's act of claiming "X" was in no sense caused by "X" being true. In my head I call this "causal disconnection" or similar phrases, but it's not a good name.
The underlying idea here is that, when you are told "X", it's useful to think about the causal chain that resulted in you being told "X". Is the truth of X a powerful force in that chain? Is it one of many competing forces? Or is it, perhaps, totally irrelevant? In some sense this is a Bayesian viewpoint on the question "suppose somebody makes a claim -- how much should you update your probability that that claim is true?"
Politics obviously abounds with this, but a good non-political example is pop-sci rumors. For instance, I often hear the claim that cicadas sleep for prime-numbered years because that minimizes the probability of overlapping/conflicting/getting-caught-by other species (explanations vary). Now, without making much effort to evaluate the truth of this statement, think about what causes people to make this claim. Well, clearly, it sounds very good, so it'll spread quickly (as a meme). Now, what if the claim was false -- how much would that fact impede its spread? Probably not so much.
(Somewhat remarkably, this suggests a concrete reason to be wary of oft-repeated claims. The fact that a claim is often repeated suggests that it spreads quickly. The reason you're hearing the claim, then, may be because it spreads quickly, and not so much because it's true.)
It's really important that the truth or falsehood of the claim has nothing to do with the question of the nature of the causal chain underlying the claim.
A related idea is that one must have great respect for -- and fear of -- social processes. I'm far from fully appreciating the consequences of this. This is also related to another comment in this thread about evolutionary processes, because those are often the causal forces behind people making claims.