ABSTRACT
Wilfrid Sellars framed contemporary philosophical debates over naturalism by recognizing tensions between two alternative conceptions of human beings in the world. The difficulty of accommodating conceptual normativity and rationality within a thorough-going naturalism has often seemed especially acute for the social sciences, as sciences of the manifest image. Some recent work on scientific practice in turn challenges Sellars's 'scientific image' by denying that science produces, or even aims to produce, a single, unified conception of the world. The application of niche construction theory to the evolution of language and symbolic-conceptual understanding treats it as public discursive practice rather than internal neurological structure. The co-evolution of language and human conceptual capacities is then a preeminent example of behavioral niche construction. Scientific understanding is not a perennial possibility always available throughout human history, or even available to rational or intelligent beings of different species or planetary ecologies.
