Early leadership researchers like Robert Carlyle and Herbert Spenser introduced “great man” theories in the late-19th century to explain how human history emerged “from the actions of Great Men” (Carneiro, 1981, p. 171). Great man theories asserted that leaders are born, not made; great leaders have inherent qualities that destine them to lead.

Great man theories became traits theory in the early 20th century, as researchers attempted to isolate the psychological characteristics that distinguish leaders from non-leaders. Rather than making assumptions about the nature or nurture of leadership characteristics, traits theory asserted that leaders have characteristics that are different from non-leaders. The goal of the great leader is to motivate people to comply. Leaders with the right traits can overcome any challenge (Kirkpatrick & Locke, 1991; Yukl, 2010; Bass, 2008; Hughes, Ginnett, & Curphy, 2005; Stogdill, 1948; Bateman & Snell, 2007).

In a review of trait theory literature from the first half of the 20th century, Ralph Stogdill (1948) identified five traits that differentiate leaders from followers: intelligence, dominance, self-confidence, level of energy and activity, and task-relevant knowledge. Richard Mann (1959) later identified intelligence as the “best predictor of individual behavior” (p. 249). Exploring the connection between personality traits and leadership, Tim Judge (2004) and his colleagues found that conscientiousness and openness to experience were the traits that correlated with effective leadership and that intelligence is only a moderate factor. They concluded that a leader’s personality is more important than their intelligence.