Majority rule is a decision rule that selects alternatives which have a majority,
that is, more than half the votes. It is the binary decision rule used
most often in influential decision-making bodies, including all
the legislatures of democratic nations.
Distinction with plurality
Though plurality (first-past-the post) is often mistaken for majority rule, they are not the same. Plurality makes the option with the most votes the winner, regardless
of whether the fifty percent threshold is passed. This is equivalent to
majority rule when there are only two alternatives. However, when there
are more than two alternatives, it is possible for plurality to choose
an alternative that has less than fifty percent of the votes cast in its
favor.
Use
Majority rule
is used pervasively in many modern western democracies. It is frequently
used in legislatures and other bodies in which alternatives can be
considered and amended in a process of deliberation until the final
version of a proposal is adopted or rejected by majority rule. It is one of the basic rules prescribed in books like Robert's Rules of Order. The rules in such books and those rules adopted by groups may additionally prescribe the use of a supermajoritarian rule under certain circumstances, such as a two-thirds rule to close debate.
Many referendums are decided by majority rule.
Properties
May's Theorem
According to Kenneth May,
majority rule is the only reasonable decision rule that is "fair", that
is, that does not privilege voters by letting some votes count for more
or privilege an alternative by requiring fewer votes for its passing.
Stated more formally, majority rule is the only binary decision rule
that has the following properties:
- Fairness: This can be further separated into two properties:
- Anonymity: The decision rule treats each voter identically. When using majority rule, it makes no difference who casts a vote; indeed the voter's identity need not even be known.
- Neutrality: The decision rule treats each alternative equally. This is unlike supermajoritarian rules, which can allow an alternative that has received fewer votes to win.
- Decisiveness: The decision rule selects a unique winner.
- Monotonicity: The decision rule would always, if a voter were to change a preference, select the alternative that the voter preferred, if that alternative would have won before the change in preference. Similarly, the decision rule would never, if a voter were to change a preference, select a candidate the voter did not prefer, if that alternative would not have won before the change in preference.
Strictly speaking, it has been shown that majority rule meets these
criteria only if the number of voters is odd or infinite. If the number
of voters is even, there is the chance that there will be a tie, and so
the criterion of neutrality is not met. Many deliberative bodies reduce
one participant's voting capacity—namely, they allow the chair to vote
only to break ties. This substitutes a loss of total anonymity for the
loss of neutrality.
Other properties
In group decision-making it is possible for a voting paradox
to form. That is, it is possible that there are alternatives a, b, and c
such that a majority prefers a to b, another majority prefers b to c,
and yet another majority prefers c to a.
Because majority rule requires an alternative to have only majority
support to pass, a majority under majority rule is especially vulnerable
to having its decision overturned. (The minimum number of alternatives
that can form such a cycle (voting paradox) is 3 if the number of voters
is different from 4, because the Nakamura number
of the majority rule is 3. For supermajority rules the minimum number
is often greater, because the Nakamura number is often greater.)
As Rae argued and Taylor proved in 1969, majority rule is the
rule that maximizes the likelihood that the issues a voter votes for
will pass and that the issues a voter votes against will fail.
Schmitz and Tröger (2012) consider a collective choice problem
with two alternatives and they show that the majority rule maximizes
utilitarian welfare among all incentive compatible, anonymous, and
neutral voting rules, provided that the voters’ types are independent.
Yet, when the votersʼ utilities are stochastically correlated, other
dominant-strategy choice rules may perform better than the majority
rule. Azrieli and Kim (2014) extend the analysis for the case of
independent types to asymmetric environments and by considering both
anonymous and non-anonymous rules.
Limitations
Arguments for limitations
Minority rights
Because
a majority can win a vote under majority rule, it has been commonly
argued that majority rule can lead to a "[tyranny of the majority]".
Supermajoritarian rules, such as the three-fifths supermajority rule
required to end a filibuster in the United States Senate,
have been proposed as preventative measures of this problem. Other
experts argue that this solution is questionable. Supermajority rules do
not guarantee that it is a minority that will be protected by the
supermajority rule; they only establish that one of two alternatives is
the status quo,
and privilege it against being overturned by a mere majority. To use
the example of the US Senate, if a majority votes against cloture,
then the filibuster will continue, even though a minority supports it.
Anthony McGann argues that when there are multiple minorities and one is
protected (or privileged) by the supermajority rule, there is no
guarantee that the protected minority won't be one that is already
privileged, and if nothing else it will be the one that has the
privilege of being aligned with the status quo.
Another way to safeguard against tyranny of the majority, it is argued,
is to guarantee certain rights. Inalienable rights, including who can
vote, which cannot be transgressed by a majority, can be decided
beforehand as a separate act, by charter or constitution. Thereafter, any decision that unfairly targets a minority's right could be said to be majoritarian, but would not be a legitimate example of a majority decision because it would violate the requirement for equal rights.
In response, advocates of unfettered majority rule argue that because
the procedure that privileges constitutional rights is generally some
sort of supermajoritarian rule, this solution inherits whatever problems
this rule would have. They also add the following: First,
constitutional rights, being words on paper, cannot by themselves offer
protection. Second, under some circumstances, the rights of one person
cannot be guaranteed without making an imposition on someone else; as
Anthony McGann wrote, "one man's right to property in the antebellum
South was another man's slavery". Finally, as Amartya Sen stated when presenting the liberal paradox, a proliferation of rights may make everyone worse off.
Erroneous priorities
The erroneous priorities effect (EPE)
states that groups acting upon what they initially consider important
are almost always misplacing their effort. When groups do this they have
not yet determined which factors are most influential in their
potential to achieve desired change. Only after identifying those
factors are they ready to take effective action. EPE was discovered by Kevin Dye after extensive research at the Food and Drug Administration. The discovery of EPE led to the recognition that even with good intentions for participatory democracy, people cannot collectively take effective actions unless they change the paradigm for languaging and voting. EPE is a negative consequence of phenomena such as spreadthink and groupthink.
Effective priorities for actions that are dependent on recognizing the
influence patterns of global interdependencies, are defeated by the EPE,
when priorities are chosen on the basis of aggregating individual
stakeholder subjective voting that is largely blind to those
interdependencies. Dye's work resulted in the discovery of the 6th law
of the science of structured dialogic design,
namely: "Learning occurs in a dialogue as the observers search for
influence relationships among the members of a set of observations."
Other arguments for limitations
Some argue that majority rule can lead to poor deliberation practice or even to "an aggressive culture and conflict". Along these lines, some have asserted that majority rule fails to measure the intensity of preferences. For example, the authors of An Anarchist Critique of Democracy
argue that "two voters who are casually interested in doing something"
can defeat one voter who has "dire opposition" to the proposal of the
two.
Voting theorists have often claimed that cycling leads to debilitating instability. Buchanan and Tullock argue that unanimity is the only decision rule that guarantees economic efficiency.
Supermajority rules are often used in binary decisions where a
positive decision is weightier than a negative one. Under the standard
definition of special majority voting, a positive decision is made if
and only if a substantial portion of the votes support that decision—for
example, two thirds or three fourths.
For example, US jury decisions require the support of at least 10 of 12
jurors, or even unanimous support. This supermajoritarian concept
follows directly from the presumption of innocence on which the US legal system is based. Rousseau
advocated the use of supermajority voting on important decisions when
he said, "The more the deliberations are important and serious, the more
the opinion that carries should approach unanimity."
Arguments against limitations
Minority rights
McGann argues that majority rule helps to protect minority rights,
at least in settings in which deliberation occurs. The argument is that
cycling ensures that parties that lose to a majority have an interest
to remain part of the group's process, because the decision can easily
be overturned by another majority. Furthermore, if a minority wishes to
overturn a decision, it needs to form a coalition with only enough of
the group members to ensure that more than half approves of the new
proposal. (Under supermajority rules, a minority might need a coalition
consisting of something greater than a majority to overturn a decision.)
To support the view that majority rule protects minority rights
better than supermajority rules McGann points to the cloture rule in the
US Senate, which was used to prevent the extension of civil liberties
to racial minorities.
Ben Saunders, while agreeing that majority rule may offer better
protection than supermajority rules, argues that majority rule may
nonetheless be of little help to the most despised minorities in a
group.
Other arguments against limitations
Some argue
that deliberative democracy flourishes under majority rule. They argue
that under majority rule, participants always have to convince more than
half the group at the very least, while under supermajoritarian rules
participants might only need to persuade a minority.
Furthermore, proponents argue that cycling gives participants an
interest to compromise, rather than strive to pass resolutions that only
have the bare minimum required to "win".
Another argument for majority rule is that within this atmosphere
of compromise, there will be times when a minority faction will want to
support the proposal of another faction in exchange for support of a
proposal it believes to be vital. Because it would be in the best
interest of such a faction to report the true intensity of its
preference, so the argument goes, majority rule differentiates weak and
strong preferences. McGann argues that situations such as these give
minorities incentive to participate, because there are few permanent
losers under majority rule, and so majority rule leads to systemic
stability. He points to governments that use majority rule which largely
goes unchecked—the governments of the Netherlands, Austria, and Sweden, for example—as empirical evidence of majority rule's stability.
