Craig Fox (University of Western Ontario)
Are there areas of science that focus directly on the construction of narratives and, if so, what role do such narratives play in interpreting data and garnering evidence? This paper argues in the affirmative, and shows that in sciences that reconstruct long-past events, narratives play very similar roles as models and theories in more traditional areas of science do. In particular, I show that narratives serve to integrate data sets that are far less informative when considered independently. That is, the probative value of some observations in reconstructing the deep past is enhanced by the integration with other observations that is made possible by additional assumptions that are licensed by the way they fit together within a provisional narrative. This integration is not unlike the more familiar way in which theories based on lawlike regularities enable different measuring devices to be calibrated. What is different, however, is that, when reconstructing the past, regularities are insufficient because often the event of interest constitutes a singular case. So what enables the integration is the provisional narrative, or sequence of sub-events that led to a target system’s evolution from an initial to a final state. The purpose of the narrative, then, is a recounting of a target system’s trajectory through state space. And the way in which the narrative serves to integrate different data sets and, thereby, make them more informative, is in part by postulating a causal sequence that brings the data sets together, making them measurements of different phenomena brought together under a single causal sequence. I illustrate this with the case of the investigation into the early history of the Earth and the origin of the Moon. The consensus among scientists is that the Moon formed from the impact ejecta launched into orbit by a giant impact between a Mars-sized proto-planet and the Earth, within the first 100 million years of the origin of the solar system. And the evidence that is largely responsible for this consensus is the hafnium-tungsten isotopic ratios of the Earth, Moon, and meteorites. But, as I show, this evidence is not actually very informative unless it can be integrated with the uranium-lead isotopic ratios of these bodies. But what licenses this integration is not the ability to calibrate these independent measures in the familiar sense. We cannot calibrate them as we can, say, calibrate a constant-volume air thermometer and a thermocouple. That is, we cannot measure a state of some target system, then vary that state, and repeat the measurements to show that the two track the same quantity, such as with the calibration of thermometers. In the case of the integration of the isotopic ratios, the two data sets only happen to be measuring the same thing in virtue of the particular sequence of events, postulated to have occurred some 4.5 billion years ago. What makes the hafnium-tungsten measurements be about the giant impact and origin of the moon is their place in the narrative. Indeed, without this narrative—more specifically, the integration with uranium-lead afforded by the narrative—the hafnium-tungsten observations are compatible with the Moon having formed yesterday (Halliday, 2003, 520).
