The Joe Biden We Know

It took three tries and more than 30 years, but Joe Biden will finally accept the Democratic Party nomination for President Thursday evening. The moment is a personal triumph, and a credit to the former Vice President’s doggedness and the alliances he has formed over decades. Yet despite all of his many years in public life, it still isn’t clear what kind of President Mr. Biden would make.

Let’s assume that the gilded testimonials to Mr. Biden’s personal character at this week’s Democratic convention are true. He is by all…