In On Tyranny, Snyder looks briefly back to the Founding Fathers and their studies of what caused ancient democracies to fail. They paid attention to Aristotle's idea that authoritarian rulers can arise when too much inequality exists in a society. Another problem, pointed out by Plato, can be the rise of demagogues, leaders who appeal to the irrational drives and emotions of a population rather than offering reasoned arguments or ideas. Such an individual can persuade a society to abandon democracy and put all the power of the state in a tyrant's hands.
More recent history, too, can help us understand how authoritarian leaders seize power. For example, Snyder explains the rise of authoritarian fascist and communist regimes as responses to inequalities brought on by globalization in the early twentieth century. Populations in places like Germany in the 1930s, Snyder says, felt that democracy was inadequate for the threats facing the country and so installed an authoritarian system and leader. Communism, likewise, gave one party a "monopoly" on power so that its single version of "reason" could not be contested.
Snyder also states that democratic systems can put in safeguards to try to prevent the rise of authoritarian leaders but that no system is completely foolproof. His book then goes to list and explain twenty ways to resist tyranny.