Chris, you are confusing economic determinism with Marxism. For a good example of economic determinism, I recommend Charles Beard's "Economic Interpretation of the American Constitution" which analyzes the various provisions on the basis of which segment of the American wealthy it would benefit.
Marxism has a much more complex approach. Marx's 18th Brumaire explains how Louis Bonaparte took forceful action against the bourgeoisie in order to defend its long term interests. Another worthwhile explanation of the differences is contained in Plekhanov's "The Materialist Conception of History".
Louis Proyect
(http://www.panix.com/~lnp3/marxism.html)