The debates of the four remaining Republican presidential candidates appear to be over, and it is no secret that Republican voters remain dissatisfied with the field. The analysts and TV talking heads keep dwelling on the same particular defects of each candidate, such as Romney’s inauthenticity, Newt’s Jekyll and Hyde character, Santorum’s fixation on social issues and Ron Paul’s dodgy foreign policy. But the entire field has shared one common defect from the start; none of them talk with any serious depth about what used to be close to the center of many presidential campaigns in times of tumult: how we should interpret the Constitution.

True, the Constitution gets a brief mention now and then. But it is amazing that there’s been virtually no serious question asked of the candidates about their extended views of, for example, the Commerce Clause of Article I, and whether they think Obamacare is compatible with it. It would provide an occasion for each candidate to anchor their limited government views in our charter of limited government, and remind the American people of the fundamental principles of that document. Ron Paul seemingly does the best job overall, referencing a strict view of the enumerated powers of Congress in Article I, Section 8, but he doesn’t really offer a fully developed constitutional philosophy.

This contrasts sharply with previous presidents and successful presidential campaigns, which often signaled important changes in direction in our understanding of the Constitution by making sustained arguments about its meaning. In modern times, Franklin Roosevelt made an extensive argument, on the eve of the 1932 election, about why the Constitution needed to be understood in new ways amidst the crisis of the Great Depression, and then again in his infamous “court packing” crusade in his second term. A few years before FDR, Calvin Coolidge, who was not the “Silent Cal” of historical repute, argued vigorously against the Progressive Era idea that’s come to be known as the “living Constitution.” And the most prominent champion of that idea was Woodrow Wilson, who enjoys the dubious reputation of being the first president to criticize the Constitution openly.

With only a few exceptions (Ronald Reagan was one), for some reason in recent decades presidential candidates have grown increasingly illiterate about the Constitution, supinely surrendering to the view that constitutional interpretation is a matter relegated to the Supreme Court. Presidents and candidates for the office throughout the whole of the 19th century took seriously not merely their duty to the Constitution, as spelled out in their oath of office “to preserve, protect, and defend” it, but their indispensable role as teachers of the American people. Most inaugural addresses of 19th-century presidents devoted half their length to discussing the Constitution and our obligations to uphold it. Today it typically receives a brief and almost ceremonial mention in most inaugural addresses.

Both liberal and conservative candidates do themselves and the American people a disservice in reinforcing the idea of judicial supremacy — the idea that the Constitution is what the Supreme Court says it is, rather than belonging to all three coequal branches of government and, ultimately, to the people. Maybe we shouldn’t blame the candidates alone for this strange gap in our modern practices. The media doesn’t reflect much on the Constitution beyond self-interested particulars of the First Amendment. And most of the leading textbooks about the presidency contain little or no discussion of the constitutional context of the office, instead treating the president as just a grander variation of a corporate CEO. This is why my “Politically Incorrect Guide™ to the Presidents” assigns letter grades on modern presidents’ “constitutional quotient” rather than judging them on their whole record, which often depends on circumstances.

It is amazing how many modern presidents had little or no constitutional philosophy of their own, even if they performed well in office in most other respects. Woodrow Wilson and Franklin Roosevelt had the most fully developed liberal philosophies of the Constitution; Harry Truman, a good president in my mind, had little, and LBJ had none. Calvin Coolidge was the most constitutionally literate Republican president of the last century, followed closely by Ronald Reagan. Eisenhower, another excellent president overall, had no constitutional philosophy of his own, and it showed in his two dreadful Supreme Court appointments, Earl Warren and William Brennan.

Judging our presidents and candidates for the office by the simple standard of whether they have a serious idea of what it means to “preserve, protect, and defend” the Constitution might be one way of prompting them to step up their game, such that we can have more confidence and enthusiasm that we’re backing someone worthy of the eminent office.

Steven F. Hayward is a resident scholar at the American Enterprise Institute, and author of “The Politically Incorrect Guide™ to the Presidents: From Wilson to Obama.”