When faced with parents who are hesitant with regards to vaccinating their children, physicians often trot out the same aphorisms. "Vaccines protect your children from harm", "vaccines protect society". But research has shown that, far from being persuasive, individuals who are hesitant with vaccination to begin with may become more entrenched in their beliefs when they are confronted with these types of arguments.

Now a new study, appearing in Nature Human Behavior, may tell us why, and it has to do with a concept called moral foundations theory.