What are the advantages and disadvantages of having a prime minister?

I assume that
you are asking in this question about the pros and cons of having a parliamentary system, with a
prime minister as the head of government, as opposed to having a system like that of the United
States where the president is the head of government. 

Perhaps the main
benefit of a parliamentary system is that it ensures that the prime minister is more or less in
control of the government.  In a parliamentary system, the prime minister is chosen by the party
that has a majority of the seats in the parliament.  If no one party has a majority, the party
that gets the most seats has the chance to try to create a coalition with other parties to make
a majority.  Either way, the prime minister is the head of the party that is in control of the
parliament.  This is good because it ensures that the prime minister will always be able to
lead.  This is in contrast to the US system where we currently have a Democratic president who
cannot lead because Congress is controlled by the Republicans.  In this way, we can say that it
is better to have a parliamentary system because it guarantees the prime minister will be
relatively capable of leading the countrys government.

Perhaps the biggest
drawback of such a system is that it lacks checks and balances.  In a parliamentary system, the
executive branch is not independent of the legislative branch.  Instead, the prime minister is
elected by the legislature and answers to the legislature.  This is in contrast to the US system
where the legislature does not select the president and the president does not have to do what
the legislature says.  To many people, checks and balances are good because they make it harder
for the government to be dominated by one party or one ideological group.  The checks and
balances make it harder to get the government to do anything, thus making it harder for the
government to do things that would infringe on the rights of the people.  This protection does
not exist in a parliamentary system.

We can argue, then, that the
parliamentary system is better because it is more efficient and worse because it lacks checks
and balances that serve to limit what government can do. 

href="https://sites.hks.harvard.edu/fs/pnorris/Acrobat/stm103%20articles/Cheibub_Pres_Parlt.pdf">https://sites.hks.harvard.edu/fs/pnorris/Acrobat/stm103%2...