Ezra Klein says he didn't find Tom Geoghegan's argument about the unconstitutionality of the filibuster convincing. Fine. But he just lost my vote for Chief Justice of the Supreme Court.
But as long as we're on the subject, let me add one further argument. The following sentence is pretty much the sum total of what the constitution has to say about how the Supreme Court operates:
The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish.
The constitution does assume that there will be multiple judges on the Supreme Court. However, it doesn't say that rulings require only a majority vote of the justices. Why? Because it never occurred to the framers that they had to say so. It was such an obvious and common convention that they just assumed it. And if anyone today tried to create a rule that effectively prevented a majority of justices from issuing opinions, they'd be (pardon the expression) laughed out of court.
The same is true for Congress. As Geoghegan notes, the framers specifically spelled out cases where non-majority votes were required, something that pretty clearly demonstrates that majority voting was the baseline they were working from. If it had ever occurred to them that anyone would seriously suggest otherwise, is there really any question that they wouldn't have made it explicit?