What type of experiences and training shape a great leader? Is it someone who from early on studied leadership, specialized in the subject and has rarely deviated from their goal? To be valuable as a professional and leader don’t we need to specialize?
David Epstein does a good job of putting our common thinking to the test in, Range[:] Why Generalists Triumph in a Specialized World (New York, NY: Riverhead Books, 2019). Epstein recaps at the end of his book what he tried to accomplish: “The question I set out to explore was how to capture and cultivate the power of breadth, diverse experience, and interdisciplinary exploration, within systems that increasingly demand hyperspecialization, and would have you decide what you should be before first figuring out who you are.” 
The Dangers of Specialization
Epstein marshals some startling facts and examples regarding the dangers of specialization in terms of its impact on an individual. He references the “Einstellung effect,” “a psychology term for the tendency of problem solvers to employ only familiar methods even if better ones are available.”  He says that specialists get so specialized that they can’t see outside the boundaries of their specialization to solve problems. In short, when you are a hammer everything looks like a nail.
Epstein argues that range means taking a different approach and that has many benefits. He cites interesting examples related to “lateral thinking with withered technology” which mean uses an apparently worthless technology with some new application. This can sometimes produce amazing results . He talks about the success of Nintendo’s Gameboy 
He also talks about how range aids the creative thinking process. With respect to comic book creators, “Broad genre experience made creators better on average and more likely to innovate.”  He discusses serial innovators: “they read more (and more broadly) than other technologists and have a wider range of outside interests” 
In short, Epstein argues that, “Facing uncertain environments and wicked problems, breadth of experience is invaluable. Facing kind problems, narrow specialization can be remarkably inefficient. The problem is that we often expect the hyperspecialist, because of their expertise in a narrow area, to magically be able to extend their skill to wicked problems. The results can be disastrous.” 
It gets worse yet. Why? “There is a particular type of thinker, one who becomes more entrenched in their single big idea about how the world works even in the face of contrary facts, whose predication become worse, not better, as they amass information for their mental representation of the world.” 
Epstein gives the comical explanation of political pundits and economic prognosticators on the TV news circuit. He says, “The average expert was a horrific forecaster.”  He gives the example as to how experts were taken by surprise regarding then sudden demise of the USSR and the reunification of Germany. So-called experts didn’t see it coming.
Learning To Drop Your Familiar Tools]
In a chilling chapter in the book titled, “Learning to Droop Your Familiar Tools,” he talks about the experts become entrenched in their approach, rather than think outside the box for new solutions. One danger is that experts are more prone to reach conclusions from incomplete data and rely on what’s in front of them 
Epstein talks about the NASA program and some of their colossal disasters, most notably the explosion of the Space Shuttle Challenger 73 seconds after launch on January 28, 1986.. NASA is the realm of specialized knowledge. He explains that, “Reason without numbers was not accepted. In the face of an unfamiliar challenge, NASA managers failed to drop their familiar tools.”  He explains how, “The Challenger managers made mistakes of conformity. They stuck to the usual tools in the face of an unusual challenge.”  Even though the mistake that led to the Challenger disaster could have been caught, it was the uniformity of thinking that lead to an organizational blind spot.
Was there no one who would defy conformity? No, that’s not the culture of many organizations, including NASA. “Congruence” is a social science term for cultural “fit” among an institution’s components—values, goals, visions, self-concepts, and leadership styles. Since the 1980s, congruence has been a pillar of organizational theory.”  Thinking outside the box is not a valued trait.
Leadership and Range
What are the implications for leadership? Epstein explains that researchers studied thousands of businesses and found that: “the most effective leaders and organizations had range; they were, in effect, paradoxical. They could be demanding and nurturing, orderly and entrepreneurial, even hierarchical and individualistic all at once. A level of ambiguity, it seemed, was not harmful. In decision making, it can broaden an organization’s toolbox in a way that is uniquely valuable.” 
The challenge: “Yet, over and over, the individual managers conformed to standard procedure no matter what the results told them, even when it clearly was not working, and even when a better system was easily discoverable.” 
The research showed…”that an effective problem-solving culture was one that balanced standard practice—whatever it happened to be—with forces that pushed in opposite directions.”  The difficulty is that many leaders don’t genuinely want contrary opinions.
“In professional networks that acted as fertile soil for successful groups, individuals moved easily among teams, crossing organizational and disciplinary boundaries and find new collaborators.”  The best organizations will build range into their corporate culture.
To sum up Parts I and II, David Epstein’s book offers a contrarian view to the drive for specialization and its virtues that permeate society from raising kids, solving problems, career and life planning, hiring people and leading organizations. This is manna from heaven from generalists everywhere.