Or maybe it's bullshit, designed to scare people into voting for bad candidates.
Even Duverger himself did not consider it some universal law, merely as a statistical trend. A better formulation would be 'under these conditions, a third party has difficulty forming and attracting voters, and an established party can survive longer than it should, purely based on merit'. Says the exact same thing, but cannot be misinterpreted as easily.
no, the law is still very much real, statistical outliers, especially during times of significant upheaval, like complete economic collapse are to be expected with the word "tend", yet we see in basically every government of the world that follows said principle that this happens
There are two types of laws in science - absolute and statistical. Absolute laws always apply, at least within the framework in which they work. For example, the laws of thermodynamics. Statistical laws, on the other hand, are trends observed in nature. For example, Allen's rule. I do not question the fact that Duverger's law, in the form I quoted, is a statistical pattern. But a great deal of damage is caused by people who treat it as a law of nature, and try to metagame the electoral process.
I mean, it doesn't sound like we're in disagreement then.
I tend to be touchy on the subject because of some... unrealistic positions sometimes passed around ten minutes before an election in a two-party system.