What do we learn from this history? If Wade's speech offers the central rationale for [the 14th Amendment's] Section Four, the goal was to remove threats of default on federal debts from partisan struggle. Reconstruction Republicans feared that Democrats, once admitted to Congress would use their majorities to default on obligations they did disliked politically. More generally, as Wade explained, "every man who has property in the public funds will feel safer when he sees that the national debt is withdrawn from the power of a Congress to repudiate it and placed under the guardianship of the Constitution than he would feel if it were left at loose ends and subject to the varying majorities which may arise in Congress."
Like most inquiries into original understanding, this one does not resolve many of the most interesting questions. What it does suggest is an important structural principle. The threat of defaulting on government obligations is a powerful weapon, especially in a complex, interconnected world economy. Devoted partisans can use it to disrupt government, to roil ordinary politics, to undermine policies they do not like, even to seek political revenge. Section Four was placed in the Constitution to remove this weapon from ordinary politics.