Time, Life and Environment: Practices of Geohistory at the Intersection of the Earth and Life Sciences

Abstract

In his great work on fossil bones (1812), Georges Cuvier compared our ignorance of geohistory to our conceptual mastery of the heavens. Several centuries of research had “burst the limits of space” and drawn back the curtain on the hidden mechanism of the universe. Yet deep time remained obscure, shielded from inquiring eyes by the inconvenient fact that the past no longer exists. To “burst the limits of time,” scientists needed to overcome this barrier—needed, in other words, to extend their epistemic reach into the deepest stretches of geohistory. This dissertation is framed by this grand epistemological challenge. How do scientists “burst the limits of time” in order to unravel the complicated thread of time, life and environment? Cuvier was among the first people to show how the vanished contents of deep time might be reconstructed from surviving material evidence. Yet his achievement did not solve the epistemological problem once and for all. Over the past two hundred years, scientists have burst the limits of time again and again—new barriers, new ruptures. It is this process that interests me. I am particularly interested in how scientists from multiple disciplines pool their conceptual and material resources to reconstruct different aspects of complex historical events. In addition, I am interested in the strategies researchers have developed to probe the interactions between living things and their environments on a range of spatial and temporal scales. The dissertation is organized into five chapters of unequal length. After a brief Preface, Chapter 1 situates the project in three overlapping bodies of literature. These are: (1) philosophical studies of the “historical sciences,” (2) philosophical discussions of paleontology, and (3) philosophical discussions of scientific practice associated with the “practice-turn.” This exercise enables me to articulate my aims for the project, and (no less important) to say what this dissertation is not about. The remainder of the chapters concern historical and philosophical topics in the sciences of geohistory. Chapter 2 examines a “start-up problem” in nineteenth century geology: how were fossils turned into a reliable yardstick for measuring geological time? I argue that in order to use fossils to measure time, geologists had to overcome a “problem of nomic measurement” (so named by Hasok Chang). Moreover, and contrary to philosophical expectations, they did not do this by formulating a theoretical explanation of the operative phenomena. Instead they pursued a more piecemeal strategy guided by practices of heuristic appraisal—something I suggest is typical of justification in start-up situations. In Chapter 3, I turn to the subject of explanation, and explore why explanations of complex historical events tend to grow more complicated over time. Using inquiry into earth’s largest mass extinction as an illustration, I argue that the main driver of explanation in geohistory is “non-explanatory work”: work that may be relevant to the evaluation of explanatory hypotheses, but that is not undertaken in the interest of testing an explanatory claim. This “drives” explanation by bringing new features of historical phenomena into focus—and this in turn creates new demands (adequacy conditions) on explanations, prompting investigators to develop more complex explanatory models. In Chapter 4, I explore the concept of “uniformitarianism”: perhaps the most contentious term in the geological literature. Since this is a polyvalent term, many commentators have assumed that its controversial status arises from a sort of semantic chaos, which sows confusion among otherwise competent language users. However, I argue that debates about uniformitarianism in geology do not arise from a mere babel of meanings. Instead, they arise from legitimate disagreements about substantive questions, for example, “Is uniformitarianism necessary?” and “When is it appropriate to offer non-uniformitarian explanations of past events?” This chapter examines these questions, and relates them to several “forms of understanding” pursued by researchers in geohistory. Finally, in Chapter 5, I explore the emergence of a new approach to stratigraphic complexity, first in stratigraphy, and then, following its creative appropriation, in paleobiology. The approach is based on pioneering models of sedimentary basin filling, and has come to be associated with an approach known as “stratigraphic paleobiology.” This chapter traces the emergence of stratigraphic paleobiology and explores how it reconfigured the cultural landscape of paleobiology following the Paleobiological Revolution. It also considers how the new stratigraphy is shaping paleontological discussion of “incompleteness” and “bias” in the fossil record.