Abstract
Over the past decades research on learning has become more diverse and complex. The concern expressed by Alexander, Schallert, and Reynolds (Citation2009/this issue) is that this diversity of theoretical perspectives has resulted in a fragmentation that is destructive to the field. Although it is important to engage in explicit discussions of how learning is construed in different traditions, Alexander et al. do not give sufficient recognition to the significant epistemological and theoretical differences between traditions; differences that make them incompatible in important respects, for instance, with respect to their units of analysis. An acceptance of incompatibilities in perspectives is not necessarily a problem. In fact, such a situation may, if the debates are grounded in a mutual acceptance of the diverse manners in which knowing and learning may be theorized, give us a richer frame of reference from which to analyze learning in its various manifestations in complex societies.