The talented National Review writer Charles C.W. Cooke has a new book out, The Conservatarian Manifesto, arguing for the rise of a new sensibility of people who "feel libertarian around conservatives, and conservative around libertarians."

I should note by way of disclosure that I feel a certain kinship with Cooke, another European writer who identifies more with the American conservative movement than the politics of his home continent.

The idea of "fusionism," meaning of a natural political and philosophical kinship between libertarians and conservatives, has a long and storied history in American politics, dating back to at least William F. Buckley's founding of National Review. Indeed, fusionism was often considered key to the successes of the Reagan and Gingrich revolutions.

But to get a sense of the necessity of Cooke's argument, one need only think back to the heady — and very distant — days of Obamania, where a parallel (and much more clunkily named) movement came to the fore: "liberaltarianism."

The political calculus for libertarians is relatively straightforward: They are a small minority — albeit an influential one — and are not completely at home in either party, but can get a lot done if they ally with one in particular. Many libertarians, quite understandably, felt betrayed by the Bush administration, especially by its foreign adventurism, new government programs like Medicare Part D, and insouciance when it came to civil liberties. They felt that they could no longer in conscience be associated with the Republican Party.

Meanwhile, the left looked increasingly amenable to libertarian ideas. The left had always been solidly socially liberal, and had moved in a much more pro-market direction in the 1990s. It looked like only a shove was needed to turn the Democratic Party quasi-libertarian.

But what really got the liberaltarian juices flowing was, of course, the genius of Candidate Obama, with his "I have heard you" rhetorical style and his ability to present a Rorschach test to almost all voters and constituencies. Obama certainly seemed progressive on social issues (is there a single person alive who believed his once-professed opposition to same-sex marriage?). He talked a great game about humility in American foreign policy and protecting civil liberties and the Constitution, about which libertarians justly feel passionate. And he seemed, at least, a moderate when it came to economic liberalism. What's more, Obama (it is so hard to recall nowadays) promised a post-partisan politics of ideas, exactly the kind of politics that would suit libertarianism best.

The apogee of this spasm of self-delusion was, of course, the endorsement of Obama by the libertarian-leaning conservative writer Andrew Sullivan, and his advocacy of the candidate over the course of not one, not two, but three Newsweek cover stories (one of which, famously, pictured Obama with a halo).

And self-delusion it was: On every issue of importance, the left has betrayed libertarians (if "betrayed" is the right word, given that they never actually bothered to promise them anything). Obama's treatment of the Constitution has been as roughshod as any of his predecessor's.

The Snowden revelations have shown that the Obama Administration has engaged in egregious spying with at least as much abandon as Dick Cheney. He invaded Libya and kills people with drones wherever he pleases. And on economics, not only has he raised taxes, but his two most significant economic policies were the Recovery Act and ObamaCare, both concepts out of the old left playbook — Keynesian fiscal stimulus and universal health care, respectively. In the meantime, on the other side of the aisle, the rise of the Tea Party has infused the Republican Party with a renewed sense of libertarianism, not only propelling Rand Paul in the Senate but also increasing the importance of the philosophy within the conservative movement.

The reason why liberaltarianism was always doomed to fail is because, at the end of the day, progressivism is an all-encompassing ideology. And while libertarians won't agree with conservatives on everything, the two can certainly agree on a lot, because of a key bedrock principle of libertarianism that is shared with conservatives but not progressives: the importance of localism.

Conservative attachment to subsidiarity — the principle that any given issue should be handled at the most local level that can handle it — and to epistemic humility offers obvious points of compromise with libertarians. For example, many conservatives are not wild about the idea of marijuana legalization — but most of them are also open to the idea of allowing states to experiment with it. Same-sex marriage is also an issue where the contrast is stark: while many conservatives straightforwardly oppose same-sex marriage, a good number believe in allowing each state to liberalize same-sex marriage, out of epistemic humility and beliefs in limited government; meanwhile, pro-same-sex marriage activists are not content with the clear victories they are winning in opinion polls and the ballot box, and are desperately trying to get the Supreme Court to invent a constitutional right to same-sex marriage.

It is exactly this sort of ideological, moralistic progressive urge that makes progressivism and libertarianism like oil and water and makes the conservative movement the natural home of libertarians. At the end of the day, an alliance with the conservative movement is the only plausible way for libertarians to effect meaningful political change in America.