When most American states adopted the primary election system in the 1970s, it seemed like a pro-democracy reform: Let each party's voters, instead of party officials in the proverbial smoke-filled room, choose their candidate for the general election.
Here's the problem: Turnout for a primary is generally lower than for a general election. Therefore, it is dominated by the party's most motivated voters -- which usually means its most extremely ideological voters. This has the effect of making each party more extreme -- it is a real threat to any Pub incumbent to be primaried from the right, or (to lesser degree) a Dem from the left, so in office, they go more extreme to forestall the possibility.
Is there a better way?
Here's the problem: Turnout for a primary is generally lower than for a general election. Therefore, it is dominated by the party's most motivated voters -- which usually means its most extremely ideological voters. This has the effect of making each party more extreme -- it is a real threat to any Pub incumbent to be primaried from the right, or (to lesser degree) a Dem from the left, so in office, they go more extreme to forestall the possibility.
Is there a better way?