The laws of nature have a special relation to counterfactuals that distinguishes them from non-laws. For example, If the Earth’s axis had been perpendicular to its orbital plane, many things would be different (for example, there would have been no seasons). But we think that the laws of nature still would be the same. Explaining this characteristic counterfactual invariance is challenging for Humean theories of laws. Humeans hold that laws of nature are mere regularities in the distribution of the non-modal properties. However, if the laws are mere regularities, why should they have any special modal status with regard to counterfactuals? Dorst (2022), and Loew and Jaag (2020) have recently offered pragmatic explanations for the counterfactual invariance of laws: We use counterfactuals for prediction and confirmation, and they serve these evidential purposes best if we hold the laws of nature fixed. Lange (forthcoming) criticizes these accounts by arguing that counterfactuals do not in fact play the relevant evidential roles. In this talk, we argue that Lange’s criticism leaves the broader Humean strategy intact by clarifying the evidential role of counterfactuals. Moreover, we argue that Humeans can consistently hold that laws are invariant under counterfactual variations despite lacking inherent necessity.

According to Humeanism, the laws of nature are the theorems of a ‘best’ system, i.e. a theory which correctly captures the non-modal facts about our universe and which offers the best trade-off between theoretical virtues such as strength and simplicity (Lewis 1973). Humeans commonly assume that there can only be one best system and accordingly only one set of laws of nature (Lewis 1994, Hicks 2018, Loewer 2007). In recent years, however, it has been argued that the possibility of cases of tied best systems—in which multiple systems score equally well in terms of the tradeoff—should be taken seriously (cf. Hall 2015, Loew and Jaag 2020, Linnemann and Michels ms.). The aim of our talk is to discuss how Humeans should best deal with such tied cases. We critically evaluate five different options, and ultimately argue that adherents of the BSA will likely have to accept the existence of indeterminate laws, whereas a kind of contextualist account looks like the best option for pragmatic Humeans (cf. Hicks et al. 2023).

According to the standard Humean account of laws of nature, laws are selected partly as a result of an optimal trade-off between the scientific virtues of simplicity and strength. Roberts and Woodward have recently objected that such trade-offs play no role in how laws are chosen in science. In this paper, we first discuss an example from the field of automated scientific discovery which provides concrete support for Roberts and Woodward's point that scientific theories are chosen based on a single-virtue threshold. However, we then use this very same example as a starting point to argue that i) by insisting on a single best theory, Humeans rely on an overly simplistic conception of trade-offs, that ii) this conception should give way to one which allows for a Pareto front of equally optimal theories, and iii) that given this new conception, threshold behaviour for a virtue like strength is a) compatible with the existence of a genuine trade-off and b) can even play the positive role of a selection criterion.

In this paper, we analyse causation in terms of factual difference-making. Factual difference-making is an alternative to counterfactual difference-making which does not face the problem of redundant causation. Our analysis defined in a framework of causal models solves many causal scenarios with which accounts in terms of counterfactual difference-making still struggle. The upshot is that causes are, perhaps, better understood as factual difference-makers rather than counterfactual ones.