Knowledge is central to our inquiry into the sense-making animal. Our approach has not followed the path of traditional epistemology that addresses questions about the sources and limitation of our knowledge and the criteria for demarcating knowledge from mere belief. Our primary concern has been with making knowledge visible. This has required, above all, highlighting the profound difference between sentience, “raw” sense experience that we may share with many other species, and the kind of sense-making that is mediated by, or delivers, knowledge. The difference is not just of degree but of kind. The feeling of warmth is not to be conflated with the knowledge that it is warm, knowledge that will ultimately lead towards the kind of judgement that it is 5°C hotter than it was yesterday. At the heart of the difference is explicitness, reflected in the word “that” as in “that x is the case”. Hence the “thatter” of the title of this chapter. Denying the fundamental nature of this difference – and squeezing out thatter – lies at the root of a scientism which overlooks or minimizes the radical break between humanity and animality and (ultimately) between humanity and the material world. It overlooks the essential character of the sense-making creatures that we are.

The view of Ernst Mach, one of Quine's most illustrious predecessors as a naturalizer of knowledge, summarized by Leszek Kołakowski, expresses this with exemplary clarity: “there is no difference between ordinary experience accessible to any being endowed with a nervous system and scientifically organized experiment. There is no break in continuity between science … and modes of behaviour characteristic of the entire animal world.” Or, to quote Mach himself: