Joel Katzav

I bring out the limitations of four important views of what the target of useful climate model assessment is. Three of these views are drawn from philosophy. They include the views of Elisabeth Lloyd and Wendy Parker, and an application of Bayesian confirmation theory. The fourth view I criticise is based on the actual practice of climate model assessment. In bringing out the limitations of these four views, I argue that an approach to climate model assessment that neither demands too much of such assessment nor threatens to be unreliable will, in typical cases, have to aim at something other than the confirmation of claims about how the climate system actually is. This means, I suggest, that the Intergovernmental Panel on Climate Change ’s focus on establishing confidence in climate model explanations and predictions is misguided. So too, it means that standard epistemologies of science with pretensions to generality, e.g., Bayesian epistemologies, fail to illuminate the assessment of climate models. I go on to outline a view that neither demands too much nor threatens to be unreliable, a view according to which useful climate model assessment typically aims to show that certain climatic scenarios are real possibilities and, when the scenarios are determined to be real possibilities, partially to determine how remote they are

I examine the warrants we have in light of the empirical successes of a kind of model I call ‘ hybrid models ’, a kind that includes climate models among its members. I argue that these warrants ’ strengths depend on inferential virtues that are not just explanatory virtues, contrary to what would be the case if inference to the best explanation provided the warrants. I also argue that the warrants in question, unlike those IBE provides, guide inferences only to model implications about which there is real uncertainty. My conclusion provides criteria of adequacy for epistemologies of climate and other hybrid models

Dispositionalism is the view that the world is, ultimately, just a world of objects and their irreducible dispositions, and that such dispositions are, ultimately, the sole explanatory ground for the occurrence of events. This view is motivated, partly, by arguing that it affords, while non‐necessitarian views of laws of nature do not afford, an adequate account of our intuitions about which regularities are non‐accidental. I, however, argue that dispositionalism cannot adequately account for our intuitions about which regularities are non‐accidental. Further, I argue that, intuitions aside, if we suppose that our world contains objects along with their irreducible dispositions, we must suppose, on pain of logical incoherence, that it contains laws of nature that are incompatible with a dispositionalist ontology. Indeed, if we suppose a world of objects and irreducible dispositions, we will have to suppose that the most prominent views of laws of nature currently on offer are all inadequate

My aim is to argue for the incompatibility of one of the central principles of physics, namely the principle of least action (PLA), with the increasingly popular view that the world is, ultimately, merely something like a con- glomerate of objects and irreducible dispositions. First, I argue that the essentialist implications many suppose this view has are not compatible with the PLA. Second, I argue that, irrespective of whether this view has any essentialist implications, it is not compatible with the kind of explanation that the PLA affords