Federica Bocchi

We reconstruct Kuhn’s philosophy of measurement and data paying special attention to what he calls the “fifth law of thermodynamics”. According to this "law," there will always be discrepancies between experimental results and scientists’ prior expectations. The history of experiments to determine the values of the fundamental constants offers a striking illustration of Kuhn’s fifth law of thermodynamics, with no experiment giving quite the expected result. We highlight the synergy between Kuhn’s view and the systematic project of iteratively determining the value of physical constants, initiated by spectroscopist Raymond Birge, that was ongoing when Kuhn joined Berkeley in 1956. Our analysis sheds light on various underappreciated aspects of Kuhn’s thought, especially his notion of progress as improvement in measurement accuracy.

In both scientific and popular circles it is often said that we are in the midst of a sixth mass extinction. Although the urgency of our present environmental crises is not in doubt, such claims of a present mass extinction are highly controversial scientifically. Our aims are, first, to get to the bottom of this scientific debate by shedding philosophical light on the many conceptual and methodological challenges involved in answering this scientific question, and, second, to offer new philosophical perspectives on what the value of asking this question has been — and whether that value persists today. We show that the conceptual challenges in defining ‘mass extinction’, uncertainties in past and present diversity assessments, and data incommensurabilities undermine a straightforward answer to the question of whether we are in, or entering, a sixth mass extinction today. More broadly we argue that an excessive focus on the mass extinction framing can be misleading for present conservation efforts and may lead us to miss out on the many other valuable insights that Earth’s deep time can offer in guiding our future.

Estimating whether the Earth’s biota is in the middle of a crisis relies heavily on comparisons between present and past data about biodiversity or biodiversity surrogates. Although the past is a crucial source of information to assess the severity of the current biodiversity crisis, substantive conceptual and methodological questions remain about how paleodiversity and biodiversity are to be properly compared. I argue that to justify claims of a current biodiversity crisis is harder than it appears. More precisely, I claim that paleodiversity measurements are incommensurable with contemporary measurements, given the different ways that biodiversity is conceptualized and operationalized. I conclude by proposing three possible ways of overcoming this incommensurability problem.

In their paper “How Causal are Microbiomes? A Comparison with the Helicobacter pylori Explanation of Ulcers,” Lynch, Parke, and O’Malley successfully argue that certain causal attributions made to the microbiome have not satisfied Koch’s postulates nor the interventionist framework. However, their argument involves an implicit assumption that cases such as H. pylori are sufficiently similar to cases involving the microbiome, such that causal attributions to both should be evaluated according to the same causal framework. Our commentary targets this assumption. First, we introduce the historical circumstances that led to the formulation of Koch’s postulates in order to differentiate the case of the microbiome from that of infectious bacteria. Then, we introduce the concept of the holobiont, the idea that hosts and their symbionts should be conceptualized as a metaphysical and biological unit. Finally, using the holobiont concept, we argue that Koch’s postulates and the interventionist framework are ill-equipped to handle the microbiome. We conclude by suggesting that a revision of what counts as microbiological causality within the holobiont is justified.