party of one

"But Achen and Bartels’s primary thesis is that most voters are influenced not by shark-related panic but by group attachments. According to research they cite, “Even in the context of hot-button issues like race and abortion, it appears that most people make their party choices based on who they are rather than on what they think.” Weil expects this, noting, “The artificial crystallization into political parties coincides so little with genuine affinities that a member of parliament will often find himself disagreeing with a colleague from within his own party, and in complete agreement with a politician from another party.” But Weil’s notion of citizenship — really of humanity — is an intellectually strict one, and is unsympathetic to the idea that people should let any kind of social group influence their decisions. For her, engagement is a moral good, in and of itself. From this perspective, the divisions that parties themselves promote are therefore responsible for voter ignorance."
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Here.