Hello. I don't really know much about politics and I might not use the correct terminology, so please excuse my lack of knowledge.

As far as I understand, in the United States (as an example) a Congress exists for the purpose of making the nation's decisions, both internal ones (e.g. laws) and external ones (e.g. treaties with other nations) using a voting system between representatives that were also elected by citizens. And there is also the military/police that enforces the decisions made by the Congress.

Why is there a need for electing a President since the Congress can decide on everything and the military/police can execute those decisions?

(Note 1: I don't mean a President/Chief in the sense of organization or representation. In other words, any assembly of people might have a representative when there is a need for represenation in another assembly, or some agent that organizes the operation of the Congress as an Entity. But the representative/organizer does not necessarily have any rights/powers in regards to the decisions being made or whether they are enforced or not.)

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    It is clearly not necessary to have a president in a democracy. The UK does not have a president. Maybe change it to "Why does the US have a president?", which is narrow enough to be answerable, and does not incorporate any unsupported assumptions. Dec 19, 2019 at 16:36
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    @RationalFragile "And I am assuming that presidential elections happen in most developed countries that are considered a democracy" That is incorrect. Parliamentary systems are also democracies, without presidential elections. Dec 19, 2019 at 16:44
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    Some systems that do have a president do not have popular elections for president. See, for example, Italy. Dec 19, 2019 at 16:57
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    @PatriciaShanahan Yes. It seems that parliamentary systems vary wildly in their purposes and roles between countries. Dec 19, 2019 at 17:01
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    I've voted to close this question, because it needs more focus. It implies many broad foundational questions about the structure of the US Constitutional Federal Republic form of government. There are books examining the structures of our trifurcated government. Dec 19, 2019 at 17:18

5 Answers 5


You don't need a president, but democratic countries do need a head of government. If not a president that position is often called a prime minister. The exact separation of powers between a Senate/Parliament/Assembly and the head of government is a complex subject and varies from state to state according to its constitution.

As to why a head of government is needed, basically, you've answered your own question. If a national assembly passes laws, doing so requires time for deliberation and incorporation into the legal system. What mechanism covers the need for quick decisions, pertaining to existing laws?

Let's take an example. Most countries have legal frameworks for emergency relief efforts and funding. If an earthquake strikes somewhere, who would activate the country's disaster relief mechanisms, if not some form of head of government? The laws exist per the Assembly, yes, but in many cases they still need day to day executive decision making to be put into effect. Taking that away would bring little obvious benefit and would severely reduce a country's short term decision making capability.

Not to mention that most countries also have the notion of annual parliamentary/assembly recesses during which the senators/representatives are not in session but rather either on vacation or back in their home jurisdictions interacting with their constituents. So they would not be quickly available to take decisions.

(would the Roman Senate system, during the Republic, count as an example of this type of government?)

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    I gave a specific example. Why does the assembly need to convene to activate an emergency disaster relief, if there is already a law on the books providing for emergency funding? But if the assembly doesn't convene and there is no head of state, who decides, "geez, that was a big earthquake, send in the national services". vs "wow, a few walls fell over and a cow got scared, no big deal, no emergency relief"? Is it the head of the emergency services agency? Does every head of agency decide what happens? What happens when it's a multi-agency issue? Dec 19, 2019 at 21:45
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    Objection! Most (if not all) prime ministers are heads of government under a head of state. See for example Prime Minister Johnson (head of government) who is under the head of state, Queen Elizabeth II.
    – Jan
    Dec 20, 2019 at 8:54
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    To add to @Jan's comment: this answer ignores the difference between head of state and head of government. In a presidential state (e.g. the USA) they are the same person; in parliamentary and semi-presidential states they are different people, with different roles and powers. While this distinction doesn't affect the meat of this answer, it does mean that parts of it are factually incorrect. Dec 20, 2019 at 10:54
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    Not every country has a singular head of state. Also, executive function is usually the province of the head of government (for example, prime minister), not the head of state.
    – phoog
    Dec 20, 2019 at 14:35
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    @ItalianPhilosophers4Monica the usual term for the boss of a government is "head of government." There certainly are municipalities that have no mayor.
    – phoog
    Dec 20, 2019 at 14:38

There are generally considered to be three parts of government (sometimes called "estates", although that is now an antique formal usage only).

  • Legislature, such as Parliament, Congress, Senate: passes laws.

  • Judiciary: judges who decide how the law is applied in particular cases when there is a disagreement, either about the facts or about how the law applies to the facts.

  • Executive: the people who actually run the government day to day.

(Aside: you sometimes hear the media referred to as "the Fourth Estate" even though they are not part of the government. This reflects their practical role in calling the government to account.)

For instance, if the Legislature passes a law saying that everyone must fill in a tax return and pay income tax, that by itself does not actually collect any tax. Someone has to print tax forms (or hopefully these days run a web site), collect and process the returns, send out tax bills, collect the money and pay it into a bank, etc. That is the job of the Executive. The Executive also has the job of responding to events (e.g. disasters, bank failures etc) within the laws made by the Legislature. Crucially, the executive is not allowed to do anything unless the legislature has passed a law telling them they can or must do it, although in practice the laws tend to give quite a lot of latitude to the executive.

Modern governments are big beasts; there are lots of laws requiring the government to do things, and the Executive is correspondingly large. Someone has to run the Executive, and the general consensus is that this should be an elected politician so that they are answerable to the electorate for the actions of the Executive.

In the UK the head of the Executive is the Prime Minister, who then delegates the running of specific "ministries" (the top level departments in the Executive) to a team of Ministers. Those Ministers then have civil servants (i.e. salaried government employees who are not elected) to carry out their wishes (at least in theory: Google "Yes Minister" for comedy about this).

In the USA the head of the Executive is the President. His first job on taking office is to appoint about 500 senior managers to run the various parts of the Executive. These appointees then have teams of civil servants in the same way as the UK.

Edit: in response to comments.

The executive in a democracy generally has a plan of action which needs new laws passed. Getting a new law passed is not a trivial business in any government. First the bill needs to be drafted by lawyers who can ensure that it means what it is supposed to. Then it has to be reviewed and amended by the legislature so that it says what they want it to. Then it has to be passed (or not) to become law. All this needs management and scheduling. There are always more good ideas for laws than there is time available, so decisions need to be made about what gets done when, and which new laws are actually going to have a chance of making it through this process. Naturally the priority will be the bills put forwards by the government.

This process is not value-neutral; the ruling party will have its policies, but the opposition will seek to derail those plans and (if possible) substitute their own. Hence the small details of legislative procedure: who gets to speak, how votes are called etc. have huge practical importance. The filibuster is a famous practical example, but there are many smaller examples. A legislator who wants to create a new law needs to have a detailed knowledge of these procedures and engage with the managers of the legislative process in order to prevent their proposals being blocked.

  • "Although in practice the laws tend to give quite a lot of latitude to the executive.", this is the cause of my confusion. For me, it is reasonable to have an Executive head but not a Legislation head nor a Juridic head because the point from being an assembly is to solve disagreement when making decisions. So what made me ask my question is that "practice" where the head has legislation and juridic power. And in the case of presidential systems, why does the Congress allow the head to have those extra powers? Dec 20, 2019 at 16:26
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    @RationalFragile Bear in mind that in the USA the President is not in charge of the Legislature, nor is the British PM the head of Parliament. Legislative business needs organising, but the legislatures in both cases have their own mechanisms for doing so, which work with the ruling party to get legislation through. Dec 20, 2019 at 16:31
  • The tri-branch structure of government is actually a gradual development in Democracies, and in early ones (e.g. ancient Athens) it didn't quite work that way.
    – einpoklum
    Dec 21, 2019 at 19:03
  • "Crucially, the executive is not allowed to do anything unless the legislature has passed a law telling them they can or must do it" is patently false in the case of a Constitutional state like the USA. There, the Constitution defines Presidential powers, not the Congress. All powers are checked to one degree or another by the other two branches, and the legislature can and does delegate some of its powers to the executive. Dec 29, 2019 at 16:40

At the heart of your question is the concept of Separation of Powers, and is fundamental to the operation of a democracy.

The President's job of course is to "faithfully execute the laws" that Congress passes, and there does need to be a way to take quick and decisive action in situations where a deliberative body would take too long to act. But the main reason for having a separate executive and legislative branch is so that they provide a check on each others' power.

Democracy is inefficient by design. The idea is that you don't want bad laws being passed for purely political reasons; you only want good ones that are necessary and proper for carrying out legitimate functions of government. To help ensure that, you want the people writing the laws and the people enforcing them to have very different political agendas, and you also need to make sure each is prevented from doing the other's job. In this way, universally acceptable laws are passed quickly and with a broad base of consensus, but controversial ones turn into a political dogfight that force opposing sides to compromise. It's not perfect, obviously, but it's better than the alternative most of the time.

Let's say that Congress passes a bill the President doesn't like. Maybe he thinks the law is unconstitutional. Maybe he thinks he knows better than Congress what the American people want. Or maybe he's just a terrible president. Either way, he has several options available:

  • Veto it. Doing so ups the ante by forcing Congress to re-pass it with a supermajority (2/3rds support) rather than a simple majority. This is very difficult to do and is the primary backstop preventing bad laws from being passed.
  • Stall, delay, or obstruct.
  • Just don't enforce it. This is technically illegal, but presidents have a pretty broad ability to make excuses. It's then up to the judiciary to determine if it was Congress or the President acting illegally. However, the judiciary is often slow and litigation difficult, which the President and Congress can and have exploited to do legally/constitutionally questionable things before.
    • He can interpret the law in a manner that is different from the way Congress intended (Obamacare mandates, for example).
    • He can prioritize government resources to other obligations he deems more important, leaving few resources to deal with others that he doesn't care about (like marijuana offenses).
    • He can enforce the law in a highly inefficient way so as to make the law effectively toothless (lax regulatory oversight for example).
    • Or he can just blatantly ignore or defy the law altogether (DACA, anyone?)

As the saying goes, democracy must be more than two wolves and a sheep voting on what to have for dinner. It seems to work best when opposing parties are all fighting with one another. We've seen bad things happen when one party is in control of everything. Fortunately, terms of office in the US are all offset from each other so that when that happens, it usually doesn't stay that way for very long.

  • At first, you say that powers (decision making and execution) must be seperated. (Agreed.) But then you go on mentioning how the president has both a way to intervene in the decision (veto..) and the execution (inefficient enforcement). And you don't give any reason for why this is the choice of the nation. (You do give personal reasons "he thinks he knows better" which explains why a president might want to intervene but not why a nation would choose to have a president.) Dec 20, 2019 at 10:06
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    "Separation of Powers...is fundamental to the operation of a democracy." For presidential republics like the US, this is true. For parliamentary states like the UK, which often have a fusion of powers between the legislature and executive, it's not true. Dec 20, 2019 at 11:03
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    @SteveMelnikoff yet there are elements of the principle of separation of powers that pertain in the UK nonetheless, particularly with regard to checks and balances. The UK and the US got there by different routes, so the terminology and the details are different, but the end result is broadly similar.
    – phoog
    Dec 20, 2019 at 15:10
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    @phoog: Sure. What I'm keen to pick up on (and which I've seen stated here more than once) is the implication (even if unintended) that the complete separation of powers seen in systems like US's is fundamental to democracy. As you say, while some separation of powers is important, parliamentary systems can function perfectly well with some fusion of powers as well. Dec 20, 2019 at 15:21
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    @SteveMelnikoff I sometimes get the impression that chauvinistic isolationist Americans are unaware that the UK's constitution has changed since the 1770's. I suppose these are the same people who believe that European legal systems, or at least civil law systems, operate on the principle of presumption of guilt. More charitably, people making these assertions probably just haven't thought very long and hard about the definitions of "democracy," "fundamental," or "separation of powers," nor about how those apply to various systems of government in use around the world.
    – phoog
    Dec 20, 2019 at 16:17

The U.S. uses a Presidential system which basically holds that there should be a separation between the people who write the laws, the people who enforce the laws, and the people who interpret the laws (Legislative, Executive, and Judiciary). The thinking was that we should be able to choose who writes our laws and who enforces our laws (the President).

The U.K. is an example of a democracy that doesn't have three Branches of Government in the same sense. They have the judicieary, but they prefer a Head of State (the Queen) who is the spiritual representative of all things British to the world, and a Head of Government, who is selected from among the people elected to make the laws to enforce the laws. (Just like the President is not directly elected, neither is the Prime Minister (head of government). In the case of the latter, he's chosen by the members in the legislature based on the party(ies) in power. The President is selected based on the weighted number of states that vote in his favor.).

In the case where a nation follows a system similar to Britains but does not have a monarchy (The definition of being a Republic) this system is called a Semi-Presidential system, and the President is only the Head of State (Semi-Presidential systems tend to range in what duties the president does, but the general rule is the PM retains some law enforcement capability or does not have equal power to the president. Europe tends to favor Semi-Presidential models while the Americas (north and south) tend to favor Presidential models (Peru and France are the only two nations in South America that are not Presidential models but Semi-Presidential) and Canada is the only Constitutional Monarchy on the Mainland of either continent(The Queen of England is also the Queen of Canada. And Australia and New Zealand for good measure.).

All nations mentioned are Liberal Democracies despite the different ways leaders are chosen. Heck a lot of democracies exist despite the lack of the Liberal adjective. In those, instead of voting for a leader, you vote if you want the current leader to keep his job... and if you vote no, and are really lucky, you'll only lose your right to vote again.

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    This answer conflates semi-presidential states (e.g. France, Portugal) with parliamentary states (much of the rest of the Europe). Also, parliamentary republics (e.g. Ireland, Germany) and parliamentary monarchies (e.g. UK) function very similarly, but differ in how they choose their heads of state, and the power granted to their heads of state. Dec 20, 2019 at 10:59
  • The third paragraph of this answer appears to imply that France is in South America. The answer could be improved if that was more clear. Dec 29, 2019 at 19:23
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    @JoelHarmon: French Guiana is an overseas territory of France and counts as French Territory as much as mainland. It is a little known fact that the largest border between France and another nation is the French Guiana-Brazil border.
    – hszmv
    Dec 31, 2019 at 11:36

Most of the answers here are accepting the question's assumption that a president is in fact necessary in a democracy. As far as I remember from grade school history, a pure democracy is one in which every decision is put to the entire electorate. There is no representation. This is clearly only workable if the electorate is relatively small, as it presumably was in the Greek city states where the term arose.

As with anything learned in grade school, and especially dim memories of the same, that is probably imprecise on the details, but it serves nonetheless to make a point.

Such a democracy surely needs no president of the electorate is sufficiently small. If you have ever tried to get anything done with a group of people, you probably noticed that the more people there are in the group, the more necessary it becomes for someone to direct the group's discussion. It also becomes necessary to designate specific people to take action on the decisions made by the group, that is, to execute those decisions. Often, those roles are merged, but sometimes they are not.

It often makes sense to designate a person or committee to have standing executive authority, rather than spending time assigning action items to different individuals as is common in smaller or less formally organized groups. From that tendency, it is a short step to having a formally organized office or set of offices for a formally organized group.

That explains why countries usually have a head of government, a chief executive. The head of state has a different function, which is to represent the state. For example, if two states are concluding a treaty or other agreement, it is the head of state who represents the state. In practice the authority to do so is usually delegated to diplomats or other officers who negotiate and sign treaties in the name of the head of state. This is in part at a legacy of the feudal era in which monarchs were the state to one degree or another. In those days, a treaty between two countries was a treaty between two people in which the they agreed to bind their heirs and successors.

Heads of state are sometimes given powers that have traditionally lain with monarchs, for example a role in forming and dissolving the legislature, or a role in approving acts of the legislature. Sometimes they have no such function. And sometimes, as in the US, the role is entirely fused with the role of head of government.

So countries, not just democracies, need a head of state for practical reasons to operate on the international stage, and countries with larger decision-making bodies need someone to execute those decisions. These roles need not be filled by one person. Some countries have a "presidency" comprising a committee rather than a unitary "president," for example. And the prime minister of the UK was originally, if I understand correctly, simply the most senior of several ministers who were collectively delegated executive responsibility.

So the answer is: a democracy doesn't need a president to be a democracy, but every country does need a head of state and some sort of executive, and "president" is a title that has been applied to the head of state in various democracies where the role has been anywhere on the spectrum between being a pure ceremonial figurehead and having complete executive authority as combined head of state and head of government.

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