Sinek opens this part by recounting a series of experiments developed by Yale professor Stanley Milgram that examined ethical dilemmas—but removed the participants’ personal sense of responsibility. Milgram’s hypothesis is as follows:

Were we humans such lemmings that if someone who outranked us, someone in a position of authority, ordered us to do something entirely counter to our moral code, our sense of right and wrong, we would simply obey? Sure it’s possible on a small scale, but on a mass scale (123)?

The “mass scale” in question being the willful obedience of Germans during the Holocaust. Milgram’s experiments sought to understand just how this tragedy happened. His findings led to a central conclusion: The more people became abstractions, dehumanized to the point of representing nothing but ideas, the more likely they were to suffer harm.

In order to counter this tendency to turn people into numbers on a spreadsheet, Sinek argues that those in authority shouldn’t have control over groups of 151 or more (Dunbar’s Number; the 150-person model). When leaders are able to get to know each of their employees personally, they proactively avoid resorting to abstraction. Relationships are a key factor in circumventing harmful decision-making on a mass scale.