Or a simple observation of facts on the ground?

無理が通れば道理引っ込む
(Muri ga tooreba douri hikkomu;
“When unreason pushes through, reason withdraws”)

Definition:

In a society where irrational force carries the day, reasonable thinking breaks down – and justice does as well. If people learn that they can get their way by being unreasonable, then people stop doing what is right. By extension, when people don’t listen no matter how logically you speak, it’s safer to keep your head down. (Disclaimer: this safety may depend on being a wealthy aristocrat with enough resources to isolate oneself from society at large; your results may vary.)

Breakdown:

We begin with the noun 無理 (muri), “unreason,” “force,” “excess,” etc. It’s marked as the subject by the particle が (ga), and the verb it performs is 通る (tooru), in conditional form. The result of this condition is the noun 道理 (douri), “reason,” “truth,” “what is right,” performing the verb 引っ込む (hikkomu), “to draw back.”

Notes:

Some versions of this saying include が after 道理 instead of eliding it. Replacing the first が with に (ni), however, is an error; 無理に通る is “to pass through [somewhere] by force.”

This kotowaza apparently comes to us from the Book of Han (漢書), in the section on Liu Xiang (劉向). It’s included as the む entry in the Edo iroha karuta set.

Example sentence:

「無理が通れば道理引っ込むで、町の中の運転手は皆少しずつ自分勝手になり、交通事故の件数が増えつつある」

(“Muri ga tooreba douri hikkomu de, machi no naka no untenshu wa minna sukoshi zutsu jibungatte ni nari, koutsuu jiko no kensuu ga fue tsutsu aru.”)

[“As reason withdraws when force prevails, so did the town’s drivers become increasingly self-centered, and the frequency of traffic accidents is on the rise.”]