When combined, 蛮不讲理 (mán bù jiǎng lǐ) literally translates to “barbarically not heeding reason.” It paints a vivid picture of someone forcefully and crudely ignoring all logic and principles, choosing brute force or sheer stubbornness over sensible discussion.
In Chinese culture, great value is placed on 理 (lǐ), or reason. To “讲理” (jiǎng lǐ - to be reasonable) is a mark of a civilized, educated, and respectable person. Engaging in reasoned discussion is the foundation of resolving conflicts and maintaining social harmony. Therefore, accusing someone of being 蛮不讲理 is a serious social criticism. It implies they are abandoning the very principles that hold society together. This contrasts with the Western concept of “stubborn.” In English, “stubborn” can occasionally be neutral or even a backhanded compliment (e.g., “she has a stubborn determination to succeed”). However, 蛮不讲理 is always negative. It's not about determination; it's about a willful and aggressive ignorance of facts, logic, and the feelings of others. It suggests a character flaw that makes productive communication impossible.
This is a common, informal term used to express frustration and criticism. You will hear it in arguments, complaints about customer service, descriptions of difficult family members, and online rants.