A prior post reviewed the recent Ezra Klein column (and related book) that argued for “reducing the polarization of American politics by democratization, including “proportional representation and campaign finance reform; . . .[making] voter registration automatic and. . . [giving] Washington, D.C., and Puerto Rico the political representation they deserve.” https://dwkcommentaries.com/2020/02/14/u-s-needs-more-democratization/
Two respected political commentators–Norman J. Ornstein, a noted author and resident scholar at the American Enterprise Institute, and Ross Douthat, a self-proclaimed conservative New York Times columnist–have discussed the Klein book, which was the basis for his column.
The Klein book cites research by political scientists showing that split ticket voting in presidential and congressional elections has virtually disappeared, that self-proclaimed independents now vote more predictably for one party over another and that such voters are now more motivated by their antipathy for the other party rather than affinity for their own. Related to all of this is the emergence of political mega-identities: “Republicans have become more cultlike and resistant to compromise or moderation” while “Democrats have an immune system of diversity and democracy.”
Ornstein also endorses Klein’s opinion that “baked into the political system devised by our framers is an increasing bias toward geography and away from people. As the country becomes more diverse, the representation and power in our politics will grow even less reflective of that dynamism. . . . At some point, the fundamental legitimacy of the system will be challenged.”
Therefore, in the book, Klein calls for eliminating the Electoral College and the Senate filibuster, allowing Puerto Rico and the District of Columbia to become states and taking steps to make the House of Representatives more reflective of the country. “Of course, even these measures , commendable though they may be, are a very heavy lift.”
Douthat also takes on the more expansive statement of Ezra Klein’s opinions in his book, “Why We’re Polarized.” 
This book, says Douthat, correctly debunks the theory that “the cure for division is just to educate people about the Right Answers to complicated policy disputes.”
Then Douthat counters Klein by relying on two other recent books, Christopher Caldwell’s “Age of Entitlement: America Since the Sixties” and Michael Lind’s “The New Class War: Saving Democracy From the Managerial Elite.”
According to Douthat, Caldwell, another conservative author and New York Times contributing opinion writer, sees the current polarization as due to the 1960’s reformers creating “through the Civil Rights Act, a structure of judicial and bureaucratic supervision and redress that gradually expanded into a rival constitutional system. This so-called ‘Second Constitution’ is organized around the advancement of groups claiming equality, not the protection of citizens enjoying liberties. And so the claims these groups make must be privileged over and against both the normal legislative process and the freedoms of speech and religion and association that the original Constitution protects.”
Lind’s book, says Douthat, sees the current polarization as “the consolidation of economic power by a ‘managerial’ upper class'” and the resulting weakening of “any institution — from churches and families to union shops and local industries — that might grant real power to groups outside the gilded city, the Silicon Valley bubble, the Ivy League gate.” This phenomenon coupled with libertarianism of Regan and Thacher promoted “economic and social permissiveness . . . [and] a new class divide, between thriving meritocratic hubs and a declining and demoralized heartland, . . . [that] explains both the frequency of populist irruptions and their consistent futility.”
The above two books, however, in Douthat’s opinion, fail to acknowledge the importance of the “secularization and institutional-Christian decline” and resulting religious polarization as important trends contributing to polarization. which Douthat will address in a future column.
Note that Douthat does not address Klein’s point about American polarization being connected with the structure of American government giving greater weight to geographical units than to the number of people.
 Ornstein, Why America’s Political Divisions Will Only Get Worse, N.Y. Times Book Review (Feb. 9, 2020).