[Rowenna Davis](http://www.guardian.co.uk/commentisfree/2009/apr/03/left-wing-politics) points out the obvious need for market-based left wing politics:
Seven months after the collapse of Lehman Brothers, the left is still failing to put forward a coherent agenda for change
….
To move forward, the left must get over its insecurities about the market and make the economic case for the society it wants to see.
She then totally fails to suggest where that position might come from. [Cosma Shalizi](http://cscs.umich.edu/~crshalizi/notebooks/socialism.html) has pointed out one framework:
“Market socialism” is a current of ideas, starting, it seems, with the Polish economist Oskar Lange, for how to make extensive use of markets without thereby creating gross economic and political inequality.
Or, as he puts it in a [book review](http://cscs.umich.edu/~crshalizi/reviews/future-for-socialism/):
[The author thinks] that both competitive markets and socialism contracted mésalliances when young and easily entrapped (to unlimited private property and central planning, respectively), but that now, in their maturity, they can and should divorce these undesirables (both rather brutish creatures, really, and one, at least, more than a bit of a whore) and wed each other, and he sketches a portrait of their connubial bliss.
These ‘market socialist’ proposals are all a bit pie-in-the-sky, suggesting ideas such as a stock market denominated in coupons. And I haven’t read the book, so have little idea how the ideas play out. But market socialism fits my prejudices far better than straight Marxism, or [Parecon](http://en.wikipedia.org/wiki/Participatory_economics).
*ETA*: more on this at [Liberal Conspiracy](http://www.liberalconspiracy.org/2009/04/07/what-is-the-lefts-approach-to-the-financial-crisis/)