In chapter 7, Grant examines the various interventions that have been attempted in order to persuade anti-vaccine mothers from their stance. Attempts to criminally prosecute negligent mothers or disallow their children from attending school have so far yielded no effect. Another approach that proved ineffective was attempting to educate them: presenting research data about the safety of vaccines, the danger of measles, or the lack of correlation with autism—none of it changed their level of interest, and in some cases, they lost even more interest. Grant compares this phenomenon to a kind of immune system: failed attempts to persuade people only fortify their beliefs.

One social intervention, however, was found to have a relatively high success rate in producing positive behavioral changes in different contexts. It’s a practice known as “motivational interviewing,” and it encourages the practitioner to shift their approach from a paternalistic attitude (educating somebody as an authority) to a collaborative one (asking questions to help people recognize their own motivations and obstacles toward change). It begins with the assumption that a person’s problem starts from ambivalence—mixed feelings resulting from a lack of clarity or focus. The practitioner then asks the patient about their personal understanding of their situation, what they want, and what they have to gain or lose by staying or changing. When they start to contemplate change, the practitioner works to raise the patient’s confidence level, and then they begin to explore the different steps they can take to autonomously attain the desired outcome.

This practice has been effective in convincing skeptical mothers to vaccinate their children, but it is also applicable in a wider variety of contexts. In one case, a woman named Betty Bigombe volunteered to act as a diplomat to convince the rebel leader Joseph Kony into peace talks. Even though Kony’s camp was initially insulted by the idea of negotiating with a woman, Bigombe was able to meet Kony and even convince him to attend peace talks through the instinctual application of motivational interviewing.