Advantages of Single-Member Districts Politics in FPTP systems tend to the center of the political spectrum, for this is usually where the most votes are. This inhibits the growth of extremism. If leaders out of touch with mainstream views control the party, it will lose, and the losing leaders will likely be replaced. The is what happened with the Republicans after the conservative Goldwater in 1964, the Democrats after the liberal McGovern in 1972, and the British Conservatives after two ineffective leaders, William Hague in 2001 and Michael Howard in 2005. Public opinion in most democracies forms a bell-shaped curve, with most people in the center. Parties that depart too far from the center penalize themselves. Some argue that the Republicans did that in 2012.
Most FPTP systems also give a clear parliamentary majority to one party thus they are called majoritarian systems-so coalitions are rarely necessary. Gains are magnified in single-member systems. in 2010, for example, the British Conservatives won only 36 Percent of the vote but took 47 percent of the seats in Parliament. Remember, seats in FPTP systems are not proportional to votes. A relatively small swing of votes from one party to another can translate into many parliamentary seats, perhaps enough to from a parliamentary majority and a new government. The United States, with its constitutionally mandated separation of powers, muddies the advantage of this system by frequently Giving the White House to one party and the Congress to another.