Just a reminder again, it is a summary based on the self-opinions and the complete article is linked to the title.
At the 2007 Commencement to the USC Law School, Munger explained it this way:
I frequently tell the apocryphal story about how Max Planck, after he won the Nobel Prize, went around Germany giving the same standard lecture on the new quantum mechanics.
Over time, his chauffeur memorized the lecture and said, “Would you mind, Professor Planck, because it’s so boring to stay in our routine, if I gave the lecture in Munich and you just sat in front wearing my chauffeur’s hat?” Planck said, “Why not?” And the chauffeur got up and gave this long lecture on quantum mechanics. After which a physics professor stood up and asked a perfectly ghastly question. The speaker said, “Well I’m surprised that in an advanced city like Munich I get such an elementary question. I’m going to ask my chauffeur to reply.”
The point of the story is not the quick wittiness of the protagonist, but rather — to echo Richard Feynman — it’s about making a distinction between knowing the name of something and knowing something.
Two Kinds of Knowledge
One is Planck knowledge, the people who really know. They’ve paid the dues, they have the aptitude. And then we’ve got chauffeur knowledge. They’ve learned the talk. They may have a big head of hair, they may have fine temper in the voice, they’ll make a hell of an impression.
Real knowledge comes when people do the work.
One way to tease out the difference between Planck and chauffeur knowledge is to ask them why.
True experts recognize the limits of what they know and what they do not know. If they find themselves outside their circle of competence, they keep quiet or simply say, “I don’t know.” This they utter unapologetically, even with a certain pride. From chauffeurs, we hear every line except this.