Set aside the myriad layers of power ploys, hypocrisy, bad faith, obfuscations and general human orneriness and cussedness that confuse the issue. At its fundamental level, an important distinction between Progressives and Conservatives is that progressives think the world can be perfected and the aim of politics is to do so; conservatives don't think the world can be perfected, and prefer social resources to be applied in fixing smaller things. This is one reason why neo-cons aren't really conservatives, and it's probably a reason the Left hates them more: acrimony is often greater among neighbors (metaphoric or real) than among total strangers.
While Jews (and others) would like to believe that Judaism is squarely on their side of the discussion, it isn't, since the Jewish discussion was well underway a millenium or two before the modern discussion ever began.
The case of Tikkun Olam demonstrates this. In contemporary progressive thought, this term is regarded highly, and serves both as a formulation of the progressive ideal as well as proof that Jews are supposed to be on the right (=left) side of the contemporary discussion. The best and most obvious illustration of this being, of course, Michael Lerner's Tikkun Magazine.
Of course, if you go back to the sources, this isn't what they were about at all. An important source of the concept is in the Gitin tractate, which offers a series of rabbinic decisions made "for the sake of tikkun olam". Take the one from today's daf yomi. The subject is the power of a husband to retract a letter divorcing his wife (called a Get) once it has been sent. Strictly legally, in some circumstances this is possible, but the Old Raban Gamliel (there was more than one) decreed that this not be permissible, "for the sake of tikkun olam", meaning he used his authority to override the logic and consistency inherent in the legal system. The Gemarrah then asks how exactly this interference was supposed to fix the world, and gives two answers. If you go with rabbi Yochanan, who was of the opinion that the Get can be retracted in the presence of a mere two men, the danger is that the retraction won't be well known, the woman will think she's free of her husband and will remarry, and her children from the second marriage will be mamzerim (translated incorrectly as bastards, but in reality a far worse status). If however you follow the opinion of rav Sheshet, who thinks the husband needs a full court of three men to do the retracting, the decisions of a court are publicized, and in some cases the woman will think she's still married even if she isn't (the decision hinges upon circumstances), and she won't get on with life.
One way or the other, the Tikkun Olam is not a Healing of the World, it's a mechanism for preventing very specific, though painful, complications. None of which makes the latter uses of the term illegitimate; it merely demonstrates that the latter use may well have started as external ideas, which someone then went looking for in the already existing tradition.
This thread began here.