My research is centrally concerned with what we know and how we know it, especially in science. My interest in these questions has taken me into a wide range of fields of philosophy, including the philosophy of biology, the history of modern philosophy (especially the writings of Locke and Hume), and the philosophy of language. Much of my recent work has focused, however, on questions surrounding scientific realism, the widespread view that our best scientific theories offer descriptions of otherwise inaccessible domains of nature that are at least probably and/or approximately true. In Exceeding Our Grasp (OUP, 2006), I argued that the most serious challenge to this view is posed by what I called the problem of unconceived alternatives. This problem arises because we choose from among competing fundamental scientific theories the one that offers the best explanation of the available evidence as the one in which our credence will be invested, but the historical record of scientific inquiry itself reveals that we routinely fail to conceive of all the theoretical possibilities that are well-confirmed by the evidence available to us before we do so, including alternative possibilities that will ultimately replace the one we have accepted on the strength of that evidence. This historical pattern constitutes the best reason we have, I suggest, to believe that there are probably fundamentally distinct alternatives to even the best contemporary scientific theories that are also well- confirmed by the evidence we now have, including some that will ultimately replace contemporary theories in the course of further inquiry, but that nonetheless remain unconceived by scientists and scientific communities of the present day. I suggest that the central remaining question concerns just where and when this problem should and should not lead us to regard fundamental scientific theories simply as powerful instruments for mediating our interactions with otherwise inaccessible domains of nature, rather than literally accurate descriptions of such domains. In this connection I have recently argued that specific features of the institutional context and incentive structure of modern professionalized science may render us even more vulnerable to this problem of unconceived alternatives than were scientific communities of the past, but the problem does not pose an equally significant challenge to theorizing in all scientific fields or for every sort of scientific research. In more recent work I have also sought to integrate this view of scientific theories with a much broader empiricist and pragmatist vision of human cognitive activity, one that recognizes the phylogenetic continuity between our own cognitive resources and those developed and deployed by other organisms, and one that sees human cognition as a resource for getting along and around in the world more generally. My most recent work in this direction proposes a novel evolutionary explanation for the distinctively externalized or objective character we ascribe to moral demands, obligations, and norms (as opposed to mere subjective preferences and social conventions). More generally, I suggest that many persistent philosophical puzzles about language, intentionality, and morality take on a very different character if we recognize distinctive capacities such as thought and language as resources evolved in lineages of creatures like us for successfully navigating a world like the one we inhabit, and if we come to regard scientific inquiry itself simply as the most sophisticated, organized, and systematic application we have of those very capacities.