There are three major left tendencies - anarchist, demsoc, and Leninist - disagreeing mainly on the kind of governing institutions that ought accompany a more egalitarian social order.

The Leninist and demsoc critique of anarchism is that anarchy tends to be hard to maintain, at least under modern conditions. This seems to me to be more correct than not.

The Leninist and anarchist critique of democratic socialism is that elected socialist parties tend to recuperated. This seems to me to be more correct than not.

The anarchist and demsoc critique of Leninism is that vanguard parties become just as brutal ruling classes. This seems to me to be more correct than not.

My instincts tend to be in favor of left unity partially for the feeling that none of us have really figured this stuff out. Or, at least, I haven't.