isn't it is) turns out to be not just an amusing parlor trick, but the tip of a very big iceberg. Gödel showed that formal systems complex enough to be interesting are inherently undecidable – there are propositions that cannot be shown, within the system, to be either true or false, and this problem cannot be obviated by ad hoc devices. This is prologue to the even more provocative claim that the great majority of our statements, whether self-referential or not, embody a descriptive/denotative bias and the "less dramatic but more pervasive paradoxes of referentiality." In the broader culture, reality comes to be understood as identical to its description. But this runs up against the problematic that any event can be described in infinitely many ways. The upshot is that it is not possible in logic (and, a fortiori, anywhere else) to comprehend sets (and other collections, like therapy groups) as simple aggregates of their members. It is, therefore, remarkable that "the so-called social sciences", in holding to the view that a group can be understood in terms of the relationships of its members (it is decidable), are working with a scientific paradigm that has been abandoned by the hard sciences that they have tried so hard to emulate from their inception. On Newman's account, the discovery of undecidability changes mathematics, physics and cosmology, and it also changes group therapy. For all of them, the universe is now bigger and, in a sense, freer. In mathematics, undecidability leads to new conceptions of proof, and in social therapeutics "the study of emotional activity is continually generative of relevant 'unstudied' activity." The resolution of emotional conflicts (like the proofs in undecidable mathematical systems) must be continuously created. "First principles" are repudiated, in favor of the continuous activity of the group. "All Power to the Developing!" (Newman & Holzman, 2003, Annual Review of Critical Psychology) This article examines the two Marxist notions, class struggle (The Communist Manifesto) and revolutionary activity (Theses on Feuerbach). Left analysis has tended both to conflate the two, and to over emphasize class struggle at the expense of revolutionary activity. Class struggle (central to revolutionary movements in the 19th and 20th centuries) has become "an outmoded modernist tool." Revolutionary activity, by contrast "is the post-modern tool-and-result – simultaneously anti-capitalist and constructive – with which human beings can change the world." Social therapy is characterized as "revolution for non-revolutionaries." In