*face palm*That would be because you don't know nearly as much about American jurisprudence as you think you do. Posner's a senior lecturer at University of Chicago (as in "Chicago school" University of Chicago) and retired Justice of the Seventh Circuit Court. Regardless whose list you're reading of most influential jurists, he's going to be at the top or damned near it. Sure, he's a prolific writer on a broad range of topics, but I'm speaking exclusively to his citations as a legal scholar and jurist.
That is being representative on a specific topic; it's the dictionary definition of it.
Yes, I know who he is. Way to miss the point, which had zilch to do with anything outside of law.
He's very widely cited on a broad range of LEGAL questions. That says precisely bugger all about whether his opinion on the topic of DRED SCOTT is representative of the consensus.
(Putting aside for a moment that that's not even close to the definition of being representative anyway).