This book charges that just about every philosophical theory of mind or language developed over the past 50 years in the West is systematically inaccurate. Systemic oppression has influenced the processes that theories of mind or language purport to identify; however, that same systemic oppression has also made it so that most middle-to-upper class White men (including most philosophers of mind or language) are ignorant of systemic oppression. Consequently, most theories of mind or language are systematically inaccurate because they fail to account for the influences of systemic oppression. Philosopher Jeff Engelhardt argues for the de-idealization of two influential theories in the philosophy of mind and language--social externalism and objective type externalism--and considers some consequences of the de-idealization project.Following the work of Charles Mills, Engelhardt argues that ideal theories adopt oppression-obscuring assumptions while nonideal theories avoid them (or at least try to). Ideal theories assume that language users are basically equal, and that social institutions and structures are basically just, but scholarship on Western social relations, institutions, and structures shows that in fact each of these is systematically influenced by oppression. Consequently, ideal theories tend to be systematically inaccurate. Moreover, since oppression systematically produces ignorance of systemic oppression, such systematically inaccurate theories are likely the norm rather than the exception.Engelhardt shows that once we've shown that oppression systematically influences the processes that determine linguistic meanings (according to content externalism), then we have reason to expand our notion of hermeneutical injustice, we have evidence that hermeneutical injustice occurs systematically, and we have grounds for expanding discussions of conceptual engineering to include questions about engineering the processes that determine concepts, not just concepts themselves.