'I'm with Mike. It seems to me that there are only "stages" if there's some sort of teleological history - and Marx certainly stressed potential, opportunity, and contingency more than a singular historical trajectory.'
That seems ok, but you can go too far with this point. Marx plainly thought that there were indeed stages in human development, and that there was progress in human development. He did not think that this was preordained, but rather an empirically perceptible trajectory. It was by no means without reversals and so on, but clearly Marx, and any thinking person understands that capitalism is an advance on feudalism, and that machinery is an advance on muscle-power. More than that, Marx intuited from the developments within capitalism that it was pregnant with its own negation, i.e. that rational organisation of the labour process was already a technical reality, whose potential could be fully realised by removing the already superceded social form of private property in the means of production.
But Ted goes too far when he writes:
'The "educative" stages are, however, only contingent to some degree. Precisely because they are "educative" there are "internal relations" between them. Thus the stages preceding the penutimate stage are "necessary" to its creation and functioning because these presuppose the requisite degree of "integral development".'
Each historical epoch has its own laws and rationale. The Dark Ages were not just a staging post on the way to the Renaissance - that would be to confuse the telescoping historical epic for the actual course of history. Feudalism's *collapse* happened to release those elements that went on to make up capitalism, but that was not pre-ordained. Nor for that matter is communism preordained, either. Marx is imagining the strong points of the industrial system with its negative aspects removed. Whether the rest of society (or at least that working class majority that has an interest) comes to share his assessment is down to them (and us, in so far as it is a matter of persuasion).