Constructivism, particularly in the formative work of Wendt, challenges this assumption by showing that the causal powers attributed to "structure" by neorealists are in fact not "given", but rest on the way in which structure is constructed by social practice. Removed from presumptions about the nature of the identities and interests of the actors in the system, and the meaning that social institutions (including anarchy) have for such actors, Wendt argues neorealism's "structure" reveals very little: "it does not predict whether two states will be friends or foes, will recognize each other's sovereignty, will have dynastic ties, will be revisionist or status quo powers, and so on". Because such features of behavior are not explained by anarchy, and require instead the incorporation of evidence about the interests and identities held by key actors, Neorealism's focus on the material structure of the system (anarchy) is misplaced. Wendt goes further than this – arguing that because the way in which anarchy constrains states depends on the way in which states conceive of anarchy, and conceive of their own identities and interests, anarchy is not necessarily even a self-help system. It only forces states to self-help if they conform to neorealist assumptions about states as seeing security as a competitive, relative concept, where the gain of security for any one state means the loss of security for another. If states instead hold alternative conceptions of security, either "co-operative", where states can maximise their security without negatively affecting the security of another, or "collective" where states identify the security of other states as being valuable to themselves, anarchy will not lead to self-help at all. Neorealist conclusions, as such, depend entirely on unspoken and unquestioned assumptions about the way in which the meaning of social institutions are constructed by actors. Crucially, because Neorealists fail to recognize this dependence, they falsely assume that such meanings are unchangeable, and exclude the study of the processes of social construction which actually do the key explanatory work behind neorealist observations.