Whenever there is a vacancy on the Supreme Court, the public gets a short refresher course on the judiciary and an introduction to the legal philosophies of the nominee and of the senators who must consent to the nomination. Then most Americans forget. What they forget particularly is that the Court and the Constitution are always vulnerable to the distorting power of ideology. And we have today a Court and a dominant political theory of the Constitution that treat the document as a tool for ideological action.

For a generation or more, the American right has controlled the terms of public debate over the Constitution. In concocting doctrines of “strict construction” and “original intent,” the legal-intellectual complex of contemporary conservatism has given the appearance of theoretical heft to potent political slogans like “don’t legislate from the bench” and “just call balls and strikes”—all in service of an ideological program to reverse the social and economic progress of the last 75 years and to protect the powerful from further infringements upon their power.

If the Constitution is the bible of America’s civic religion, then it is no exaggeration to brand today’s right constitutional creationists. These creationists take the word of the text literally and infallibly—though only when it suits them. They are not unaware that it’s impossible to be a creationist consistently and constantly. Even Justice Antonin Scalia, their patron saint, calls himself a “faint-hearted originalist,” and will at times join rulings at odds with his purported methodology (frequently, it seems, in cases where originalism produces answers he does not like). But the politicians among them are quite aware that it is the pose of certitude that makes their program appealing to so many lay Americans. It is perhaps what is most notable about the right’s approach to the Constitution: not the creationism per se but the fixity of the fundamentalist attitude that undergirds it.

But the Framers of our Constitution gave us something that they knew should not be set in amber—that could be amended over time. What were the original values that animated the document, and how can we remain faithful to them? That is the question Americans—progressives and conservatives alike—must learn to address like grown-ups.

For too long progressives have wrestled with the question only to come short of the answer. They have complained about the right’s step-by-step co-opting of the conversation about the Constitution, but they have not countered with their own narrative. One rebuttal to constitutional creationism is, of course, constitutional evolution: You have original DNA. Then life happens, and you must adapt and evolve. But some progressives have been reluctant to go in this direction, fearing, with justification, that talk of a living or evolving Constitution activates precisely those fears of relativism and judge-driven subjectivity that fuel the political success of “strict construction.”

In the following exchange, the third installment of our “First Principles” series, we explore that disagreement. How should progressives frame and develop their counterarguments against the conservative theories that have proven so persuasive? Geoffrey R. Stone of the University of Chicago Law School and William P. Marshall of the University of North Carolina School of Law find the answer in what they call “The Framers’ Constitution”: the idea that the principles set forth in the Constitution do not change, but that interpretation must evolve over time.

Doug Kendall of the Constitutional Accountability Center and Jim Ryan of the University of Virginia School of Law embrace the “new textualism” theory advanced by thinkers such as Yale’s Akhil Amar. They argue that progressive values are inherent in the Constitution and the amendments that have followed, and that liberals should always base their constitutional arguments on text.

It’s a debate that has been playing out lately and with intensity in progressive jurisprudential circles, and we are delighted to have the opportunity to bring it to the wider community. We have few tasks more important than rebutting the conservative line on the law. The provocative dialogue in these pages will help us do that more effectively.