Myths are powerful and widespread human beliefs that shape our thought.
One of the most powerful and persistent myths is that political beliefs are arrayed along a one-dimensional spectrum from left to right. The terms left, right, leftist, rightist, left-wing, right-wing, etc., are widely used to describe politics in almost every country of the world.
The source of the myth is the politicians who wish to be reelected. The one-dimensional spectrum allows them to represent their reelection struggle as a partisan effort: I am a rightist, so everyone on the right must vote for me, and the people who vote against me are leftists.
Political journalists are therefore the biggest propagators of this myth. And they are dead wrong.
Why should everybody who has a leftist political belief about global warming also have a leftist political belief about terrorism and a leftist political belief about taxation and a leftist political belief about Sharia law and a leftist political belief about freedom of the press and a leftist political belief about ultra-nationalists and a leftist political belief about the proposed landfill in their city and a leftist political belief about women's rights, etc.?
No reason.
In reality, human beings have a remarkable diversity of political opinion with different beliefs about dozens, if not hundreds of political issues. There is no force which causes one belief to imply other beliefs; at best there are correlations between beliefs, and the more beliefs one tries to throw in the pot, the weaker the correlation.
Who are the victims of the left-right myth? The voters, in two senses: first because their political choices are constrained by the myth, and second because their civil society is polarized by the myth.
The most diverse array of political parties appears in nations that are recently democratizing. As the first elections approach, numerous parties are formed, with factions not representing left and right, but typically representing regional or familial or professional affiliations. But as soon as the elections are over and the winners are installed in office the myth-making begins and the parties are conveniently arrayed along a left-right spectrum. This greatly improves the odds of incumbents returning to office at the next election. The larger political parties try to marginalize and absorb the smaller ones.
Even in countries with a viable multi-party system, the parties are generally depicted as far left, left-of-center, right-leaning, and far right, for example.
At election times, people are discouraged from regarding the election process as a cooperative effort to pick the most qualified statesman to govern the country; instead voters are persuaded that there is a giant competitive struggle between the leftists and rightists in their country to "win" the election and "defeat" the opponents. So the politicians manage to translate their own one-dimensional struggle for reelection to a one-dimensional partition of the population.
I believe the left-right myth is an almost unavoidable consequence of democratic politics. Only a highly educated and politically astute population can see through the myth and understand that politicians must work together for the good of the people. Only such a population can insist upon a form of political accountability that transcends mere elections.
[There is one sense in which a left-right split can be defended: if the quality being measured can be represented numerically, as is the case with economic class (which can be measured in terms of income over a period of time, or net worth, or even total assets). But this is not the common use of the term - indeed journalists and commentators often point out that the rich may be "left." Furthermore, economic class is more properly considered a social classification rather than a political one.]