The shortcomings of the approach used by Parsons and the erroneous conclusions that were drawn from it highlight the importance of facts and data to supplement any qualitative analysis. Without data to adjudicate theoretical disagreements, qualitative analysis is at best informed opinion. However, this is not to say that data is a panacea to otherwise intractable disagreements in theory as there are limits to what data can tell you. Thus, the best approach is to use hard data, like statistics, in conversation with soft data, like ethnographies. In the case explicated by this reading, even this hybrid approach used by Eberstadt is incapable of any definite answers, but in leveraging data analysis to refine the scope of theoretical inquiry, a social scientist is at least able to to move closer to an answer.
Given technological and conceptual limits, there are, by necessity, plenty of things that are unknowable to us now. However attempting to place limits on human knowledge and capability is a fool’s errand. Just as people a hundred years ago would not have predicted the speed of the development of medical technology or electronic communication, people now are ill-equipped to declare insurmountable technological and conceptual barriers to human understanding. As such, to preemptively declare certain things unknowable and avoid seeking their answers is to impose unjustified and ultimately self-defeating limitations.
I agree with your assertion that the piece, without its hard supporting data is really an “informed opinion.” There was definitely not enough evidence to support the claim at the end of the piece to form a conclusion. Either this could be the beginning of a longer study to actually find supporting information for a claim on the mortality of Russians or this is a phenomenon that cannot be explained at the moment.
There are however qualitative studies in political science that do not need hard quantitative data to be able to form a conclusion. In this case it is the quantitative nature of what is being studied, the increased mortality rate of a country, that warrants the quantitative evidence. Had the focus just been on the mental reactions of the Russian people to the fall of the Soviet Union, deep immersion resulting in personal accounts might be able to draw more convincing conclusions