General Discussion
In reply to the discussion: What are your true feelings about supporting the Democratic Party of today? [View all]cprise
(8,445 posts)...that converge surprisingly well.
A quick jumping off point is the Political Compass: http://www.politicalcompass.org/uselection2008
There are the writings of Marx; whether you value his anticapitalist critique, his utopianism, or both or neither.
The emergence of science and humanism, which formed the background for the development of capitalism, socialism, unionism and communism... different ways of grappling with self-determination
There is also the overlap between Ecology and egalitarianism, called environmentalism
Of course, there are also exclusionary or negative criteria that define the Left: One shouldn't be a reactionary, i.e. someone who prefers to make instant judgements of individuals and situations according to superficial features like clothes or skin color. 'Stand your ground' laws could be considered an ultimate way to enable reactionary violence, for instance.