1) The attempt to write recipes for the cookshops of the future is ALWAYS wrong, whether such an attempt springs from marxist or anti-marxist premises. And Lou put his finger on the core here: the moralism (and hence contempt for the working class) which inevitibly comes to dominate such projects.
2. Most attempts to argue for OR against marxism as a science show an impoverished conception of *both* science and marxism. Paleography is one of the most successful of all sciences, and its predictive power is nil. Geology also flourishes, with little predictive power even in general terms and, as of yet, no predictive power in concrete situations in which such a predictive power would save lives. Despite jokes (usually accurate) about "the weatherman," both meteorology and climatolgy are powerful and flourishing sciences, with very mixed predictive power. In fact, one of the main achievements of these sciences lately has been to undercut the belief that weather *is* or ever will be predictable.
3. Marxism is a science *of capitalism*, not of the whole universe, or even all of history. As with climatology, its "predictions" are extremely limited. Capitalism will (over and over again) self-destruct. That we know. What we do not know, and can never know until it happens, is whether in one of those periodic self-destructions the working class will succeed in asserting itself to smash capitalism and begin the effort to build a socialist society. The "mutual ruin of the contending classes" is ALWAYS a possibility, perhaps even a probability. Rosa Luxemburg's imaging of this principle needs always to be remembered: "Socialism or Barbarianism." That is a scientific truth. A science or sciences attempting to expand that "or" can only be an indefinitely large collection of "if ... then" propositions. It can describe the general domain of those "ifs," but it cannot predict either that they will occur or the specific historical form they will take.
Put another way: "Science" has become a fetish within my lifetime, as one can see in the innumerable ads depicting a man (usually a man) in a white coat announcing that "Science says." The first OED reference to "science" in the modern sense goes back to the early 19th century, but even so many 19th-c usages of the term (including, I believe, Marx's use) retain much of its earlier suggestions of "systematic and corrigible knowledge," not the kind of grade-school scientific fetish Chuck invokes in his baiting reply to Lou. General and special relativity and gravity, in some remote "ideal" sense, explain the clutter surrounding the monitor in front of me. But it would be pretty grotesque for me to try to predict the future of that clutter using the principles of those scientific laws in the abstract.
Marxism's systematic knowledge of capitalism can in some of its most abstract formulations provide powerful illuminations of pre-capitalist modes of production. Ellen Wood, *Peasant-Citizen and Slave: The foundations of athenian democracy* (Verso, 1988) is an example of such an extension beyond the bounds of Marxist knowledge proper (the dynamic of capitalism).
Moreover, even predictive sciences (e.g., physics) to grow must extend well beyond laboratory tests of hypotheses. And their most powerful results explain *after the fact* rather than predict before the fact. So it is with marxism -- and that is a strength, not a weakness. It is a weakness only from the perspective of elementary-school conceptions of science.
4. As with meteorology, Marxism as a science cannot predict tomorrow's specific events, though it can tell us, rather more eloquently than can the pseudo-science of "economics," why those events are unpredictable. (Marxism, remember, is a critique of political economy, not an "economic" theory or model.)
5. Except in the most general sense of "systematic and corrigible knowledge of possibilities," there probably is no such thing as a "science of socialism." A market-centered economy will collapse into a command or a capitalist economy or into chaos. That we know. (China today probably represents the most humane and intelligent example of "market socialism" the world will ever know. Not very humane, and not very intelligent.) I take Engels's statments in *Anti-Duhring* as to "scientific socialism" as an example of using science to refer to such systematic knowledge of possibilities, not an assertion that it has the exactness of chemistry or paleography.
6. Writing when science had become a fetish imaged by the "man in a white coat," Paul Sweezy insisted that there could be a science of capitalism but NOT of socialism. The inner necessity of socialism is precisely to smash a world (capitalism) which is subject to abstract "laws" (value, competition, progress) and to create a world defined by freedom, not "law." (I don't remember where Sweezy says this; it might have been in a "REview of the Month," co-authored with either Huberman or Magdoff.) Marxism can negate some positions as to what socialism can or will be (utopian socialism, socialism achieved by electoral means, socialism depending on an absolute majority of people before it can come into existence, etc.) It cannot give us a blueprint for socialism -- or even predict that socialism will arive before capitalism has destroyed the liveability of the earth.
Only the religious could argue that socialism is inevitable, and inevitably successful. Marx put the point when, very near the end of his life, he responded to a reporter's query, "What is?" with a single word, "Struggle." That we know, as did the ancient subjects of Marx's doctoral dissertation.