In Chinese culture, which often values social harmony (和谐, héxié) and the preservation of “face” (面子, miànzi), direct confrontation is generally avoided. To call someone's idea a 谬论 (miùlùn) is therefore an extremely strong and direct move. It's not just a disagreement; it's a complete dismissal of the other person's intellectual position. Compare this to the Western concept of “calling out a logical fallacy.” In English-speaking internet culture or academic debate, identifying a “straw man” or “ad hominem” argument can be a common, almost technical, part of a discussion. In China, using 谬论 is less about pinpointing a specific type of logical error and more about a wholesale rejection of the entire premise. Using it in a casual setting would be seen as overly aggressive and could cause the other person to lose face, damaging the relationship (关系, guānxi). It is primarily reserved for formal debate, academic critique, or political rhetoric where the stakes are high.
谬论 is a formal and serious term. You will most often encounter it in written form or in formal speech.
Its connotation is always negative, dismissive, and authoritative. You would never use it to describe your own past beliefs unless you wanted to strongly distance yourself from them.