 In the context of the relationship between those growing forces and the relations of production (the economic structure), Marx propounds two claims which might look to be in tension with each other. First, that the productive forces have explanatory primacy over the relations; that is, that the level of development of the productive forces explains the nature of the economic structure. And second, that the economic structure has considerable effect on the forces; not least, that the economic structure controls (facilitates or frustrates) the development of the productive forces. It is this combination of claims which confirms that the “first primacy thesis”—that “the level of development of the productive forces in a society explains the nature of its economic structure” (G. Cohen 2014: 289)—is best understood as functional in form.