Republican Sen. Thom Tillis wants forgiveness for helping advance some of President Donald Trump’s choices. The retiring North Carolina senator is admitting regret, but his latest explanation suggests he still has not grasped the damage at the heart of those decisions.

Tillis is promoting “How to Lose Friends and Antagonize Presidents,” his new memoir and political manifesto about Trump’s mistakes and his own role in advancing them. The book is presented, at least partly, as an exercise in accountability.

That reckoning includes Tillis’ support for Robert F. Kennedy Jr., a vaccine conspiracy theorist whose brain worms outnumber his medical degrees. Kennedy was part of the rogues’ gallery of Trump Cabinet nominees whom Republicans helped place in positions of power.

Kennedy later fired every member of the Vaccine Advisory Board and selected multiple fellow vaccine skeptics as replacements. The reconstituted board overhauled the vaccine schedule, including recommendations involving measles, which is making a comeback in states including Pennsylvania and South Carolina.

Before Kennedy’s confirmation, Tillis said he hoped the outsider would “go wild” with new ideas. Even a worm could have predicted that putting a conspiracy theorist in charge might produce precisely that sort of chaos.

During an appearance on “The Weeknight” to promote his book, Tillis faced a personal question from cohost Luke Russert. Russert is the father of a 10 week old daughter who is far too young for the routine measles vaccine, which begins at 12 to 15 months.

Russert asked Tillis, “Did he go wild enough for you?” It was a direct question about the consequences of empowering Kennedy and the risks created for children who are not yet old enough to receive the routine vaccine.

Tillis responded, “I’m not worried about your daughter because you’re going to make an informed decision and you have the means and the access.” The answer treated a public health danger as though it were merely a matter of individual education and resources.

Russert then explained that, under the longtime guidance of actual experts, infants cannot receive the measles vaccine until after 12 months. Tillis replied, “Is it illegal to get it sooner?”

Tillis continued by saying Russert “don’t have to worry” about the new vaccine schedule because “you’ve got an educated choice in the resources.” But at 10 weeks old, the child did not have the choice Tillis appeared to imagine.

The exchange captured a deeper problem with the MAGA philosophy and the Republicans who enabled it. Tillis seemed to view the danger as an individual problem with an individual solution, detached from the decisions and circumstances of everyone else.

Under that approach, the United States becomes not a united country but a collection of hundreds of millions of rugged individualists whose choices supposedly never affect their neighbors. Public health, however, makes the absurdity of that thinking especially clear.

The same narrow logic says people with enough retirement money need not care whether Social Security helps their neighbors. It says parents with children in a good school can ignore a collapsing educational system, while people living on a hill can disregard flooded homes in the valley.

Ignoring neighbors carries moral implications, including the decidedly old fashioned question of whether people are their brother’s keeper. It also fails as a practical matter because neighbors who are sick, poor or uneducated will eventually affect the wider community.

Vaccinations do not protect only the person receiving them. They also protect neighbors who cannot be vaccinated because they are too young, are undergoing cancer treatment or have immune systems compromised by an autoimmune disorder.

When enough people receive vaccines, a virus has a much harder time gaining a foothold. That protection, known as herd immunity, extends to people who cannot safely be vaccinated and children who remain too young to receive a shot.

Kennedy now intends to establish a new clinic at the National Institutes of Health focused on vaccine injuries. The move would devote more government resources to an agenda constructed around the same crackpot conspiracies that defined his rise.

In theory, Tillis should regret helping make that agenda possible. His exchange with Russert suggested something more troubling than an unfortunate vote: Even while asking for forgiveness, he may still not understand why his choice was wrong.