Changing the standard of evidence or the definition of success after it's been met — so that no evidence can ever be sufficient to establish a claim.
During the early COVID-19 pandemic, a common pattern: when vaccines showed 90%+ efficacy against infection, the response was "but what about transmission?" When transmission data came in, it shifted to "but what about long-term effects?" Each standard was reasonable in isolation — but they were deployed serially as the previous one was satisfied, suggesting the conclusion ("vaccines are ineffective") was fixed and the standards were selected to protect it.
Moving the goalposts feels like rigorous skepticism. "I just want more evidence" sounds like intellectual virtue. The manipulation lies in never applying the same scrutiny symmetrically — the shifting standard only applies to the unwanted conclusion, not to the preferred one. It makes genuine inquiry look like an endless obligation.
When a critic's evidentiary demands escalate rather than converge as more evidence is provided — and when the pattern is asymmetric (they never apply the same shifting standards to claims they want to believe).