Which of the following is a formal definition? The rise of demagogues, which can be described as political leaders who come to power by stimulating the emotions of the people, threaten true democracies and leave political systems open to tyranny. Demagogues have become increasingly common in our current political climate. One contributing factor is the advent of social media websites. These sites enable "echo chambers" where facts are ignored and misguided ideas and opinions are amplified, allowing troublesome leaders to gain attention and power. A demagogue (noun) is defined by Dictionary as "a person, especially an orator or political leader, who gains power and popularity by arousing the emotions, passions, and prejudices of the people." Writer H. L. Mencken offers an observant definition of a demagogue: "the demagogue is one who preaches doctrines he knows to be untrue to men he knows to be idiots."