Sen. Rand Paul, R-Ky., center, with Sens. John Cornyn, R-Texas, left, and John Thune, R-S.D., speaks about Planned Parenthood on Capitol Hill in Washington, Wednesday, July 29, 2015. (AP Photo/Manuel Balce Ceneta)

The 300-odd young libertarians packed into Catholic University's student center were the elect of the elect. They'd scored invites to the Young Americans for Liberty annual conference because -- according to an email pitch to sponsors -- they could be "the future congressmen, entrepreneurs, policy makers, and activists that will restore our republic."

And they were not fans of Planned Parenthood. In a short evening of conversations, no young libertarian activist said he disagreed with Sen. Rand Paul's (R-Ky.) effort to bar any federal funds for the family planning group. At a bar near the conference, one table echoed with arguments about the ethics of abortion, and the politics of Paul's move.

"Planned Parenthood should not be funded by taxpayer dollars," said Hannah Malstrom, 26, a student at the University of Central Arkansas. "We were all once 20 weeks old. If I was ripped limb from limb, and my organs were sold on the black market, I would not be a happy camper. Another big stance in libertarianism is opposition to the death penalty. It's not right to play God when someone has done something wrong -- so why is it right to play God with someone who has done nothing wrong?"

[Rand Paul says the GOP can defund Planned Parenthood before the recess]

Rand Paul's politics are a constant source of debate on the libertarian right and left. Some think he's lurched too far toward military interventionism. Some think he's too close to the Republican establishment. but Paul's abortion views are less nettlesome than liberal observers of libertarianism seem to think. In April, ThinkProgress's Judd Legum wrote confidently that Paul was "not a libertarian"; his first evidence was that the senator "vehemently opposes abortion rights." This week, Little Green Footballs's Charles Johnson wrote that "Rand Paul likes to present himself as a civil libertarian, but his stance on reproductive rights is straight from the darkest, most regressive part of the Republican Party’s war on women."

Rand Paul says he will continue pushing to cut federal funding for Planned Parenthood over a dispute about fetal tissue. (Reuters)

The evidence for Paul's heresy is his sponsorship of legislation to define life as beginning at conception -- something liberals see as antithetical to "choice." Doctrinal libertarians don't necessarily agree.

When former Rep. Ron Paul (R-Texas) ran for president, he talked relentlessly about his career as an obstetrician. He told a story about seeing a viable-seeming baby in the garbage outside of a clinic, and of the shudder he felt. He said all that and founded Young Americans for Liberty, part of a largely successful effort to turn out young voters. Young Republicans, according to most polling, are even more anti-abortion than their Generation X or baby boomer parents.

"If you believe in the Constitution, and the protection of life under our Constitution, it's perfectly within the scope of libertarianism to protect life at all stages," said Rep. Justin Amash (R-Mich.), who endorsed both Pauls for president. "It's perfectly reasonable to apply the equal protection clause to protect that. Not just reasonable -- essential."

The libertarian-minded conservatives who've won elections have won them as Republicans; in the modern Republican Party, pro-life views are almost a precondition for success. Libertarians outside the arena have more of a debate about abortion. The Libertarian Party has generally nominated pro-choice candidates for office, like its 2012 presidential contender Gary Johnson. Some of the more anarchist or minarchist dabblers in libertarian politics view laws against abortion as the denial of a human right.

"The proper groundwork for analysis of abortion is in every man's absolute right of self-ownership," wrote the influential libertarian intellectual Murray Rothbard in his 1982 book The Ethics of Liberty. "This implies immediately that every woman has the absolute right to her own body, that she has absolute dominion over her body, and everything in it. This includes the fetus." And that logic has stuck with plenty of libertarians.

"The libertarian position is unequivocal: the mother has the absolute right to abortion, period," said Justin Raimondo, the editorial director of the libertarian AntiWar.com, and a sometime critic of Rand Paul's political choices. "The 'right to life' does not include the 'right' to life within someone else's body. Of course, one may consider abortion -- of, say, an 8-month-old fetus -- immoral, but many things are considered immoral by many people, and this is irrelevant to the question of whether it ought to be permitted."

But even libertarian advocates of abortion rights can see the case against taxpayer funds going to a family planning group. And one thing all libertarians have in common is a revulsion toward liberals trying to tell them what they really think.

"The fundamental question is about the moral status of the fetus," said Megan McArdle, a libertarian-leaning columnist for Bloomberg View. "If nothing is done, then in three or six or eight months, that fetus will be a person, who has a right to be protected from the use of force -- and most libertarians would not argue that the father has the right to beat it to death simply because he is coercively being forced to help feed and clothe it. Liberals have generally resolved the moral tension by clumsily reading the imminent life out of the calculation, which doesn't so much solve the problem as agree to pretend it doesn't exist."