Many writers say historical materialism holds that the thoughts and actions of individual human beings are causally determined by economic factors. They take historical materialism to be a species of causal determinism, and incompatible with libertar­ ianism, the view which affirms that human choices are free and denies that they are determined. I know of no text where Marx explicitly addresses the issue of free will and determinism, and doubt that he has any firm opinion on this issue. The belief that historical materialism involves a species of causal determinism about human actions probably derives from the erroneous idea that the ‘determination’ of production relations by productive powers and of the social superstructure by its economic basis are cases of efficient causes determining effects. Now that we have (I hope) disposed of this idea, we can take a new look at the tex­ tual evidence which might lead us to think that historical mater­ ialism is committed to causal determinism.