“A foolish consistency,” the philosopher Ralph Waldo Emerson once noted, “is the hobgoblin of little minds.” No one has accused Gov. Brown of being small minded. Why be surprised when he completely reverses himself as he did the other day on vaccinations?

Less than three years ago, Mr. Brown signed into law a plan allowing parents to place in public schools children who had not been vaccinated for diseases like polio, measles, mumps, smallpox and whooping cough. These once were plagues that killed thousands of children yearly, but by the end of the last century they had been virtually eradicated from industrialized countries. Vaccinations did that job.

The bill Mr. Brown signed in 2012 required parents not wanting to meet schools’ vaccination standards to present written proof they had heard from a health professional the pluses and minuses of getting the shots, which are often dispensed free, at public expense. He attached a signing message that essentially negated the law he had just helped create: It ordered public health officials to craft a form where parents could simply claim vaccinating their children violates their religious beliefs.

Never mind that no organized or even quasi-organized religion, from Roman Catholicism to Christian Science to Orthodox Judaism to Hinduism, Scientology and Wiccanism, opposed vaccination then. Only the black Muslim Nation of Islam does now.

The next 30 months saw two outbreaks of pertussis (whooping cough) and one – much more publicized – burst of measles that allegedly began at Disneyland, which has no vaccination rules.

No one blamed Mr. Brown for those disease flare-ups. No doubt he keeps track of the news and realized that if a similar outbreak ever reached epidemic proportions, he would be blamed. Disease, not construction projects like bullet trains or water tunnels, could become his most prominent legacy.

Which Way, Guv?

When a much tougher public school vaccination law reached his desk this month, he signed it instantly. It takes effect next year.

“The science is clear that vaccines dramatically protect children against a number of infectious and dangerous diseases,” went his latest signing message, “…the evidence shows that immunization powerfully benefits and protects the community.”

Where in 2012 Brown spokesmen rationalized his move by saying he aimed “to take into account First Amendment religious freedoms through an extremely narrow exemption,” this time there was no mention of either religion or an exemption, other than for home-schooled kids and children with medical reasons not to be vaccinated.

No form this time where parents too lazy or too fearful to get their kids vaccinated can easily lie by checking a box saying they are religiously opposed to the shots.

No foolish consistency here from Mr. Brown, who has not just vacillated, but completely reversed himself in the space of three years. It is not the first time he has done that, the most famous prior occasion coming after the June 1978 passage of the Prop. 13 property tax limits. Back then, Mr. Brown had spent the spring as the chief opponent of the initiative, sponsored by anti-tax gadflies Howard Jarvis and Paul Gann.

When it passed – by 30 percent – Mr. Brown instantly became its most active proponent, quickly meeting with Messrs. Jarvis and Gann, signing enabling legislation that still plagues the state with nonsensical definitions of what constitutes a change of ownership.

Back then, there were no crazies to dog Mr. Brown’s path toward embracing Prop. 13. This time, there are plenty of misinformed parents still determined not to vaccinate their kids. They may qualify a referendum for next fall’s ballot, trying to cancel the new law. They’re still staging vocal protests.

Don’t expect Mr. Brown to change his mind again. He is far too practical (some call it opportunism). He knows, as he did when he issued his signing message in 2012, that opposition to vaccination is based primarily on the widely circulated myth of a link to autism, since recanted by the British academic whose flawed study is at its base.

Don’t expect Mr. Brown ever to acknowledge his signing message of three years ago was a big-time error. While he’s prone to reversing himself, public mea culpas are not a habit for this former seminarian.

This reversal was strictly a practical matter. As Messrs. Jarvis and Gann discovered long ago, Jerry Brown can be pragmatism (or opportunism) personified.

Mr. Elias is author of the current book “The Burzynski Breakthrough: The Most Promising Cancer Treatment and the Government’s Campaign to Squelch It,” now available in an updated third edition. He may be contacted at tdelias@aol.com