The crux of the matter is that democratic legitimacy isn’t merely a correlative of a ruler’s share of the vote. The leader are elected to serve not just the people who voted for them but also the many who did not.
The issue is how the relationship between supporters and opponents is managed. In part this is a matter of rules and institutions to constrain a leader’s power and to allow the aggrieved to find redress. These should include a robust account of citizens’ basic rights, independent courts to enforce them and free media to monitor them.
Beyond documents and institutions, the difference between crass majoritarianism and democracy resides in the heads of the mighty. Democrats have a bedrock understanding that the minority (or often majority) who did not vote for them are as much citizens of their country as those who did, and are entitled to a respectful hearing; and that a leader’s job is to deliberate and act in the national interests, not just those of his supporters.(The Economist, emphasis mine)
The full article is worth reading.