It owes its origins to the medieval monarchies of France, England and Scotland in which executive authority was vested in the Crown, not in meetings of the estates of the realm (i.e., parliament): the Estates-General of France, the Parliament of England or the Estates of Scotland. The concept of separate spheres of influence of the executive and legislature was copied in the Constitution of the United States, with the creation of the office of President of the United States. Perhaps ironically, in England and Scotland (since 1707 as the Kingdom of Great Britain, and since 1801 as the United Kingdom) the power of a separate executive waned to a ceremonial role and a new executive, answerable to parliament, evolved while the power of the United States's separated executive increased. This has given rise to criticism of the United States presidency as an "imperial presidency" though some analysts dispute the existence of an absolute separation, referring to the concept of "separate institutions sharing power".
Presidential governments make no distinction between the positions of head of state and head of government, both of which are held by the president. Most parliamentary governments have a symbolic head of state in the form of a president or monarch. That person is responsible for the formalities of state functions as the figurehead while the constitutional prerogatives of head of government are generally exercised by the prime minister. Such figurehead presidents tend to be elected in a much less direct manner than active presidential-system presidents, for example, by a vote of the legislature. A few nations, such as Ireland, do have a popularly elected ceremonial president.
A few countries (e.g., South Africa) have powerful presidents who are elected by the legislature. These presidents are chosen in the same way as a prime minister, yet are heads of both state and government. These executives are titled "president", but are in practice similar to prime ministers. Other countries with the same system include Botswana, the Marshall Islands, and Nauru. Incidentally, the method of legislative vote for president was a part of Madison's Virginia Plan and was seriously considered by the framers of the American Constitution.
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 as head of state is criticism of the state itself.
Presidents in presidential systems are always active participants in the political process, though the extent of their relative power may be influenced by the political makeup of the legislature and whether their supporters or opponents have the dominant position therein. In some presidential systems such as South Korea or the Republic of China (on Taiwan), there is an office of prime minister or premier but, unlike in semi-presidential or parliamentary systems, the premier is responsible to the president rather than to the legislature.
Through making more than one electoral choice, voters in a presidential system can more accurately indicate their policy preferences. For example, in the United States of America, some political scientists interpret the late Cold War tendency to elect a Democratic Congress and a Republican president as the choice for a Republican foreign policy and a Democratic domestic policy.
It is also stated 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. Critics of this view note, however, that presidents cannot typically be removed from power when their policies no longer reflect the wishes of the citizenry. (In the United States, presidents can only be removed by an Impeachment trial for "High Crimes and Misdemeanors," whereas prime ministers can typically be removed if they fail a motion of confidence in their government.)
Critics respond that if a presidential system's legislature is controlled by the president's party, the same situation exists. Proponents note that even in such a situation a legislator from the president's party is in a better position to criticize the president or his policies should he deem it necessary, since a president is immune to the effects of a motion of no confidence. In parliamentary systems, party discipline is much more strictly enforced. If a parliamentary backbencher publicly criticizes the executive or its policies to any significant extent then he/she faces a much higher prospect of losing his/her party's nomination, or even outright expulsion from the party.
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 important legislation that has been proposed by the cabinet is considered to be a vote of no confidence is thus means the government falls and new elections must be held, a consequence few backbenchers are willing to endure. Hence, a no confidence vote in some parliamentary countries, like Britain, only occurs a few times in a century. In 1931, David Lloyd George told a select committee: "Parliament has really no control over the executive; it is a pure fiction." (Schlesinger 1982)
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. In the United States, Republican Congressman Bill Frenzel wrote in 1995:
Many people consider presidential systems to be more able to survive emergencies. A country under enormous stress may, supporters argue, be better off being led by a president with a fixed term than rotating premierships. France during the Algerian controversy switched to a semi-presidential system as did Sri Lanka during its civil war, while Israel experimented with a directly elected prime minister in 1992. In France and Sri Lanka, the results are widely considered to have been positive. However, in the case of Israel, an unprecedented proliferation of smaller parties occurred, leading to the restoration of the previous system of selecting a prime minister.
The fact that elections are fixed in a presidential system is considered to be a welcome "check" on the powers of the executive, contrasting parliamentary systems, which often allow the prime minister to call elections whenever he sees fit, or orchestrate his own vote of no confidence to trigger an election 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 cannot alter to suit his own needs. Theoretically, if a president's positions and actions have had a positive impact on their respective country, then it is likely that their party's candidate (possibly they) will be elected for another term in office.
Winning the presidency is a winner-take-all, zero-sum prize. A prime minister who does not enjoy a majority in the legislature will have to either form a coalition or, if he is able to lead a minority government, govern in a manner acceptable to at least some of the opposition parties. Even if the prime minister leads a majority government, he must still govern within (perhaps unwritten) constraints as determined by the members of his party - a premier in this situation is often at greater risk of losing his party leadership than his party is at risk of losing the next election. On the other hand, once elected a president cannot only marginalize the influence of other parties, but can exclude rival factions in his own party as well, or even leave the party whose ticket he was elected under. The president can thus rule without any allies for the duration of one or possibly consecutive terms, a worrisome situation for many interest groups. Juan Linz argues that
Constitutions that only require plurality support are said to be especially undesirable, as significant power can be vested in a person who does not enjoy support from a majority of the population.
Some political scientists go further, 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 not conducive to democracy, and that militaries have tended to play a prominent role in most of these countries. Nevertheless, certain aspects of the presidential system may have played a role in some situations.
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 in disagreement and government is not working effectively, there is a powerful incentive to employ extra-constitutional maneuvres to break the deadlock.
Ecuador is sometimes 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 teargassed, while another was kidnapped by paratroopers until he agreed to certain congressional demands. From 1979 through 1988, Ecuador staggered through a succession of executive-legislative confrontations that created a near permanent crisis atmosphere in the policy. In 1984, President León Febres Cordero tried to physically bar new Congressionally-appointed supreme court appointees from taking their seats. In Brazil, presidents have accomplished their objectives by creating executive agencies over which Congress had no say.
It should be noted that this alleged authoritarian tendency is often best seen in unitary states that have presidential systems. Federal states, with multiple state (or provincial) governments that are semi-sovereign, provide additional checks on authoritarian tendencies. This can be seen in the United States, where there are 50 states, each semi-sovereign, each having their own 3 branch elected government (governor, legislature, court system), police, emergency response system, and military force. If an extreme extraconstitutional action, such as the President dissolving the Congress, occurred within the Federal government of the United States, would not necessarily result in the President being able to rule dictatorially since he or she would have to deal with the 50 state governments.
In Congressional Government, Woodrow Wilson asked,
Consider the example of the increase in the federal debt of the United States that occurred during the presidency of Ronald Reagan. Arguably, the deficits were the product of a bargain between President Reagan and Speaker of the House of Representatives Tip O'Neill: O'Neill agreed not to oppose Reagan's tax cuts if Reagan would sign the Democrats' budget. Each side could claim to be displeased with the debt, plausibly blame the other side for the deficit, and still tout its own success.
On the other hand, many observers believe that federal budget surpluses of the late 1990s in the United States were a direct result of divided government. A Republican Congress refused to allow Democratic President Bill Clinton to increase domestic spending, while Clinton refused to allow Congress to cut taxes. The combination of spending restraint and high revenues led to the elimination of the annual budget deficit.
In parliamentary systems, unpopular leaders such as Tyler can be quickly removed by a vote of no confidence, a procedure which is reckoned to be a "pressure release valve" for political tension. Votes of no confidence are easier to achieve in minority government situations, but even if the unpopular leader heads a majority government, nonetheless he is often in a far less secure position than a president. Removing a president through impeachment is a process mandated by the constitution and is usually made into a very difficult process, by comparison the process of removing a party leader is governed by the (often much less formal) rules of the party in question. Nearly all parties (including governing parties) have a relatively simple and straightforward process for removing their leaders. If a premier sustains a serious enough blow to his/her popularity and refuses to resign on his/her own prior to the next election, then members of his/her party face the prospect of losing their seats. So other prominent party members have a very strong incentive to initiate a leadership challenge in hopes of mitigating damage to the party. More often than not, a premier facing a serious challenge will resolve to save face by resigning before he/she is formally removed - Margaret Thatcher's relinquishing of her premiership being a prominent, recent example.
In The English Constitution, Walter Bagehot criticized presidentialism because it does not allow a transfer in power in the event of an emergency.
Finally, many have criticized presidential systems for their alleged slowness in responding to their citizens' needs. Often, the checks and balances make action extremely difficult. Walter Bagehot said of the American system "the executive is crippled by not getting the law it needs, and the legislature is spoiled by having to act without responsibility: the executive becomes unfit for its name, since it cannot execute what it decides on; the legislature is demoralized by liberty, by taking decisions of others [and not itself] will suffer the effects". (ibid.)
A number of key theoretical differences exist between a presidential and a cabinet system:
Presidential systems also have fewer ideological parties than parliamentary systems. Sometimes in the United States, the policies preferred by the two parties have been very similar (but see also polarization). In the 1950s, during the leadership of Lyndon Johnson, the Senate Democrats included the right-most members of the chamber - Harry Byrd and Strom Thurmond, and the left-most members - Paul Douglas and Herbert Lehman. This pattern prevails in Latin American presidential democracies and the Philippines as well.
In practice, elements of both systems overlap. Though a president in a presidential system does not have to choose a government answerable to the legislature, the legislature may have the right to scrutinize his or her appointments to high governmental office, with the right, on some occasions, to block an appointment. In the United States, many appointments must be confirmed by the Senate. By contrast, though answerable to parliament, a parliamentary system's cabinet may be able to make use of the parliamentary 'whip' (an obligation on party members in parliament to vote with their party) to control and dominate parliament, reducing its ability to control the government.
Some countries, such as France have similarly evolved to such a degree that they can no longer be accurately described as either presidential or parliamentary-style governments, and are instead grouped under the category of semi-presidential system.