Although it is not perfect, the presidential system of government, as typified by the United States (U.S.) is the best system of government ever conceived. By creating a system where the public can remove administrations, without changing the legal basis for government, democracy aims at reducing political uncertainty and instability, and assuring citizens that however much they may disagree with present policies, they will be given a regular chance to change those who are in power, or change policies with which they disagree. This is preferable to a system where political change takes place through violence. Democracies are also more peaceful. Democratic nations do not aggressively attack their neighbors; they seek to resolve differences peacefully. The market forces become the overriding concern in a democratic state. "Immanuel Kant, the original proponent of the democratic peace, contended that in democracies, those who pay for wars -- that is, the public -- make the decisions, so they are understandably cautious."
A presidential system, or a congressional system, is a system of government of a republic where the executive branch is elected separately from the legislative. The defining characteristic of a presidential government is how the executive is elected, but in nearly all presidential systems the president is both head of state and head of government, and has a fixed term of office. Elections are held at scheduled times, and cannot be triggered by a vote of confidence or other such parliamentary procedures. The executive branch is unipersonal. Members of the cabinet serve at the pleasure of the president and must carry our the president's policies. "The government which is elected by the democratic procedures becomes the absolutely legitimate government. If legitimacy is strong, then it becomes culturally taboo to overthrow it. It even becomes taboo not to see it as 'our government.' Because U.S. citizens think this way, the United States is politically stable."
There are also a few countries - the Czech Republic and South Africa being examples - which have powerful presidents who are elected by the legislature. These presidents are chosen in the same way as a prime minister, yet are both heads of state and heads of government. These executives are titled "president," yet are constitutionally identical to prime ministers. Some political scientists consider the conflation of head of state and head of government duties to be a problem of presidentialism because criticism of the president cum head of state is criticism of the state itself.
A president, by virtue of a fixed term, may provide more stability than a prime minister who can be dismissed at any time. Stability was virtue prized highly by the framers of the Constitution, as we see in the writings of James Madison in the Federalist Papers. "Among the numerous advantages promised by a well constructed Union, none deserves to be more accurately developed than its tendency to break and control the violence of faction. The friend of popular governments never finds himself so much alarmed for their character and fate, as when he contemplates their propensity to this dangerous vice."
A prime minister is usually chosen by a few individuals of the legislature, while a president is usually chosen by the people. According to supporters of the presidential system, a popularly elected leadership is inherently more democratic than a leadership chosen by a legislative body, even if the legislative body was itself elected. In some parliamentary systems though, such as Israel's, the party leader is chosen by the party's rank and file membership through primaries.
It is also claimed that the direct mandate of a president makes him or her more accountable. The reasoning behind this argument is that a prime minister is "shielded" from public opinion by the apparatus of state, being several steps removed. Despite the existence of the no confidence vote, in practice, it is extremely difficult to stop a prime minister or cabinet that has made its decision. To vote down the cabinet's legislation is to bring down a government and have new elections, a step few are willing to take. Hence, a no confidence vote in some parliamentary countries, like Britain, only occurs a few times in a century.
The fact that a presidential system separates the executive from the legislature is sometimes held up as an advantage, in that each branch may scrutinize the actions of the other. In a parliamentary system, the executive is drawn from the legislature, making criticism of one by the other considerably less likely. According to supporters of the presidential system, the lack of checks and balances means that misconduct by a prime minister may never be discovered. "Presidents and legislatures are directly elected and have their own fixed mandates. This mutual independence creates the possibility of a political impasse between the chief executive and the legislative body for which there is no constitutionally available impasse-breaking device."
Some supporters of presidential systems claim that presidential systems can respond more rapidly to emerging situations than parliamentary ones. A prime minister, when taking action, needs to retain the support of the legislature, but a president is often less constrained, even when checks on their power are in existence. A presidential system establishes the presidency and the legislature as two parallel structures. Critics argue that this separation of powers creates undesirable gridlock, and that it reduces accountability by allowing the president and the legislature to shift blame to each other. It is also claimed that the difficulty in removing an unsuitable president from office before his or her term has expired represents a significant problem.
Other supporters of presidential systems sometimes argue in the exact opposite direction, however, saying that presidential systems can slow decision-making to beneficial ends. Divided government, where the presidency and the legislature are controlled by different parties, is said to restrain the excesses of both parties, and guarantee bipartisan input into legislation.
Many people consider presidential systems to be superior in surviving emergencies. A country under enormous stress may, supporters argue, may be better off being led by a president with a fixed term than rotating premierships. The fixed term may also serve to allow an unpopular president to maintain a policy that many people may not agree with, but turns out to be the correct course for the country.
The fact that elections are fixed in a presidential system is likewise often held as a valuable "check" on the powers of the executive. While parliamentary systems often allow the prime minister to call elections whenever he sees fit, or orchestrate his own vote of no confidence to trigger one when he cannot get a legislative item passed, the presidential model is said to discourage this sort of opportunism, and instead force the executive to operate within the confines of a term he or she cannot alter to suit his or her own needs.
Winning the presidency is a winner-take-all, zero-sum prize. Unlike a prime minister, who may have to form a coalition, a president's party can rule without any allies for four to six years, a worrisome situation for many interest groups. Juan Linz argues that
The danger that zero-sum presidential elections pose is compounded by the rigidity of the president's fixed term in office. Winners and losers are sharply defined for the entire period of the presidential mandate. . . losers must wait four or five years without any access to executive power and patronage. The zero-sum game in presidential regimes raises the stakes of presidential elections and inevitably exacerbates their attendant tension and polarization.
Some political scientists and argue that presidential systems have difficulty sustaining democratic practices, noting that presidentialism has slipped into authoritarianism in many of the countries in which it has been implemented. Seymour Martin Lipset and others are careful to point out that this has taken place in political cultures unconducive to democracy, and that militaries have tended to play a prominent role in most of these countries.
A disadvantage of presidential systems is the tendency towards authoritarianism or totalitarianism. Some political scientists say that the presidentialism is not constitutionally stable. According to some political scientists, such as Fred Riggs, presidentialism has fallen into authoritarianism in every country it has been attempted, except the United States. "Embattled Presidents are often tempted to resort to desperate and even unconstitutional measures in order to bypass Congress and achieve their goals. Sometimes, as in the Philippines in 1972, the President suspends Congress and rules by martial law and executive orders."
In a presidential system, the legislature and the president have equally valid mandates from the public. There is often no way to reconcile conflict between the branches of government. When president and legislature are at loggerheads and government is not working effectively, there is a powerful incentive to employ extra-constitutional maneuvers to break the deadlock. Ecuador is presented as a case study of democratic failures over the past quarter-century. Presidents have ignored the legislature or bypassed it altogether. One president had the National Assembly tear gassed, while another was kidnapped by paratroopers until…