I don’t know is there is already a specific term for this error, but I have no doubt that it can be addressed with more conventional labels. Still, I think this is a common enough issue, that it might be worth giving it it’s own name, so I’m coining one here. Presumptuous, I know, but I’m doing it anyway. So,…
This occurs when somebody tries to counter quantitative research by raising the prospect of a confounding variable without considering the way the research might already have addressed that variable. For example, someone counters claims about anthropogenic global warming by stating that global temperatures vary considerably over time, thus ignoring the fact that such variations are considered in research on the topic to begin with. Another common example occurs when people try to counter a claim that links a given ethnic group with a stigmatized activity by speculating on the reasons someone specific might engage in the activity. (E.g. __% of this people commit suicide.” “…Well, maybe someone lost his job or his girlfriend left him.”) Absent a reason to believe the issue actually skews the results of the study, this information would not count as evidence against it; It might well help to round out the story, but it would not help to refute the initial observation.
Such suggestions should certainly be taken seriously if they are framed in terms of questions about methodology. Legitimate questions about the representativeness of a statistical sample or the possibility that a confounding variable could result in a misleading correlation are common, and they they are an important check on bad research, but this should be distinguished from variables raised as objections without addressing the methodology in any meaningful way.
What makes this style of reasoning an error is the complete absence of any attempt to engage the initial study (or studies). The allegedly confounding variable is offered as an alternative story preferred by the speaker without any serious effort to address the likelihood that it really invalidates the initial claims in question. In many cases, the appeal seems to be rooted in story telling. The speaker would simply rather tell this story than that one; the numbers don’t enter into it.
Arguably, this is just a variety of circular argument, but it is a very specific form of circular reasoning that seems common enough to merit some focus of its own.