Jean-Jacques Rousseau, Emile, 1762
Political parties are quasi-official institutions designed to acquire the reins of government. They sponsor candidates for public office by providing the resources needed to conduct a campaign for election. As a condition of their sponsorship, they require that the candidates support the party, thus giving the party ultimate control of the elected officials.
In the United States, our governmental system is defined by our Constitution, and nothing in our Constitution expresses or implies the need for political parties. They are an extra-Constitutional invention, devised to advance partisan interest. The problem of partisanship was well understood by the framers of our Constitution:
"When the Founders of the American Republic wrote the U.S. Constitution in 1787, they did not envision a role for political parties in the governmental order. Indeed, they sought through various constitutional arrangements such as separation of powers, checks and balances, federalism, and indirect election of the president by an electoral college to insulate the new republic from political parties and factions."
A "party system" developed in our nation because our early leaders used their standing to consolidate their power. Politicians in a position to do so institutionalized their advantage by forming political parties and creating rules to preserve them and aid their operation:
"The Democratic-Republicans and Federalists invented the modern political party -- with party names, voter loyalty, newspapers, state and local organizations, campaign managers, candidates, tickets, slogans, platforms, linkages across state lines, and patronage." (Wikipedia)
These features advance party interest at the expense of the public interest. They show how political parties are an embodiment of human nature; they put self-interest above all other considerations. They function precisely as a thoughtful person would expect them to function.
Political parties are grounded in partisanship. Partisanship is natural for humans. We seek out and align ourselves with others who share our views. Through them, we hone our ideas and gain courage from the knowledge that we are not alone in our beliefs. Partisanship gives breadth, depth and volume to our voice. In and of itself, partisanship is not only inevitable, it is healthy.
On the other hand, partisans have a penchant for denigrating those who think differently, often without considering the salient parts of opposing points of view. They seek the power to impose their views on those who don't share them, while overlooking their own shortcomings. Communism and National Socialism showed these tendencies. Both had features that attracted broad public support throughout a national expanse and both degenerated into destructive forces because their partisans gained control of their governments.
The danger in Communism and National Socialism was not that they attracted partisan support; it was that the partisans gained control of government. In general, partisanship is healthy when it helps us give voice to our views. It is destructive when it achieves power. All ideologies, whether of the right or the left, differ from Communism and National Socialism only in the extent to which their partisans are able to impose their biases on the public.
Partisanship is a vital part of society ... provided it is always a voice and never a power. The danger is not in partisanship, it is in allowing partisans to control government.