Karl Popper, the great philosopher of science and the open society, once remarked that, “No rational argument will have a rational effect on a man who does not want to adopt a rational attitude.”

It’s a truism to keep in mind as we watch the inexorable politicization of the controversy over childhood vaccination for measles and other highly communicable diseases. The current measles outbreak is a self-inflicted wound, the product of indulging willfully narcissistic parents’ desire to substitute hazy, anxious fantasies for sound medical advice and allowing them to withhold vaccines from their children. Partisan reductionism is another of our self-inflicted traumas, a bitter narrowing of discernment and reflection that transforms every question of life or policy into a political litmus test or electoral wedge.

There was a kind of morbid fascination in watching this all play out, as a variety of Republican presidential aspirants scrambled to turn the measles outbreak into the sort of political capital that is the currency of choice in their party’s primaries, where the GOP’s right-wing wields disproportionate influence.

Kentucky Sen. Rand Paul, a physician, predictably staked out the most extreme position: “I have heard of many tragic cases of walking, talking, normal children who wound up with profound mental disorders after vaccines,” he told an interviewer. “I’m not arguing vaccines are a bad idea. I think they are a good thing. But I think the parent should have some input. The state doesn’t own your children. Parents own the children, and it’s an issue of freedom and public health.”

Where to start? As one Republican political consultant who inhabits the real world with the rest of us immediately pointed out, vaccinations are “not a liberty issue; they’re a public health issue.” Moreover, the notion that children are their parents’ property is grotesque. Parents have the principle role in safeguarding their children’s welfare, providing for their education and acculturating them with the values in which they believe. That relationship, however, is custodial and not absolute as “ownership” implies. Were it not so, how could we have laws against child abuse? This is another example of Paul’s hare-brained affinity for libertarianism, a pseudo-philosophy whose devotion to hyper-individualism ultimately undermines the very concept of a common good, which is the foundation of a rational public health policy.

New Jersey Gov. Chris Christie inevitably sought a middle ground where there is none. “You know it’s much more important what you think as a parent than what you think as a public official,” he said. “And … parents need to have some measure of choice in things as well, so that’s the balance that the government has to decide.” This, of course, is the governor who against all epidemiological science and advice fueled the Ebola hysteria by insisting on mandatory quarantines for volunteer health workers returning from West Africa. Why lead, when you can pander?

The 19th century British wag might well have had Christie in mind, when he described a parliamentary opponent as someone “who wants to run with the fox and hunt with the hounds.”

Wisconsin Gov. Scott Walker took what amounts to the moderate position in this field, arguing that decisions over public health laws ought to be left to the states. That’s good conservative ideology, but wretched science and public health policy, since the vaccination model requires that 90 percent or more of those susceptible to infection be inoculated to defeat a disease. That’s what the United States had done until early in this century, when the anti-vaccine irrationality began to take hold in certain affluent communities. In Santa Monica and parts of Orange County, for example, renewed attention to this issue has revealed that in some preschools barely 50 percent of the children have been vaccinated.

This week’s comedic high point or rational nadir occurred when Thom Tillis, a Republican senator from North Carolina mused on how he opposes government regulations that compel restaurant employees to wash their hands after using the rest room. In the face of that notion of “freedom” there is little to do, but to suggest that this family not let him book the reservation when they next dine out.

Beyond grim amusement, there is a more troubling issue lurking here, and that is the Republican Party’s ever-more deeply entrenched hostility to scientific knowledge. In part, that’s a consequence of the right-wing’s reflexive antipathy to anything that can be characterized as “elite opinion,” though science by virtue of its method is one of the most democratic of human pursuits. In part, it’s a result of the importance of Evangelical Christians — many of them Biblical literalists — in the new Republican base.

Whatever the reason, the GOP risks becoming not only the party of the white, the nativists, the Southern and the old, but also of the insistently ignorant. Recent polling shows that a plurality of Republicans still reject the concept of evolution and hold to some form of “intelligent design” or a literal reading of Genesis. Similarly, an even larger plurality refuses to believe in the reality of climate change. An even larger percentage say that, even if climate change is occurring, human activity has no role in the process. If anti-vaccine sentiment is now to become a litmus test among the party’s White House hopefuls, it will make a perfect trifecta of willed ignorance.

On the party’s television arm, Fox News, this past week, the network’s legal analyst, Andrew Napolitano, not only praised Paul for making “the pro-freedom case,” but also argued “that under the Constitution (and the Declaration of Independence) people are free to reject ‘scientific orthodoxy.’ ” That’s perfectly true; Americans are free to hold all sorts of eccentric, outlandish and, even, wicked opinions. The rest of us, however, are just as free not to give such views any weight when it comes to formulating public policy, particularly in areas like health, where a mature political intelligence always is obliged to seek the common good.

As Popper said on another occasion, “True ignorance is not the absence of knowledge, but the refusal to acquire it.”

Tim Rutten is a columnist for the Los Angeles News Group. ruttencolumn@gmail.com.