Arguments

Science is about likelihood, not epistemological hubris. So we can use deduction to arrive at a conclusion. We do not simply deny categories of evidence because there at newer techniques, especially not if science is less progressed in this area however easier that makes pure critique. That is a god of the gaps, and a weird hybrid of appeal to ignorance, arguing from incredulity, and raising the bar.
Which is how skeptics always argue: pure critique

People fall for this but the issue is you have to pick from flawed ideas and solutions, preferring the one which is more likely to occur and deals with what you actually need done or averted, and arguing from pure critique doesn't make that clear.

Or is supported by evidence, has predictive validity, and preferably is simpler than the alternatives. Exact mechanistic explanations are useful, but lower priority since one can always return to that with better analysis and tools

In the case of ethnonationalism, for example, if you let them engage in pure critique you are essentially arguing against their perfect unexamined civic nationalism. However, if you question them on that and make them defend the likelihood of their ideal then you present the strengths of ethnonationalism rather than defending its faults (relative to their utopia). Which is the issue. Civic nationalism just isn't going to happen. Right or wrong, identity simple is.

Save can be seen in debates between capitalism and socialjsm