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

Paul Horwich claims that theories of meaning ought to accommodate the commonsense intuition that meanings play a part in explaining the use of words. Further, he argues that the view that best does so is that according to which the meaning of a word is constituted by a disposition to accept, in some circumstances, sentences in which it features. I argue that if meanings are construed thus, they will in fact fail to explain the use of words. I also argue that if we insist, as Horwich does, on the commonsense assumption that meanings are a species of entity, all versions of the view that meaning is constituted by our dispositions to use words will have to be rejected. I do not, however, claim that such theories ought to be rejected. My point is that they are incompatible with the requirements of commonsense. Further, I suggest that it is premature to impose such requirements on theories of meaning.

In 'The Weakness of Strong Justification' Wayne Riggs claims that the requirement that justified beliefs be truth conducive (likely to be true) is not always compatible with the requirement that they be epistemically responsible (arrived at in an epistemically responsible manner)1. He supports this claim by criticising Alvin Goldman's view that if a belief is strongly justified, it is also epistemically responsible. In light of this, Riggs recommends that we develop two independent conceptions of justification, one that insists upon the requirement that beliefs be truth conducive and another that insists that they be epistemically responsible. It will then, on his view, be possible to properly evaluate beliefs with regard to each conception of justification. Riggs, however, is mistaken in supposing that the two epistemic requirements are independent. If a belief is responsibly arrived at, it is therefore likely to be true. He is thus also mistaken in supposing that the two epistemic requirements are incompatible. This mistake arises because Riggs assumes that justification is possible or, at least, that it involves standards that are akin to our own. Moreover, once this assumption is made explicit, we can see why a notion of justification that connects epistemic practice with likely truth is significant

FIRST PARAGRAPH I have argued that dispositionalism is incompatible with the Principle of Least Action (PLA) (Katzav 2004). In ‘Katzav on the Limitations of Dispositionalism,’ Brian Ellis responds, arguing that while naïve dispositionalism is incompatible with the PLA, sophisticated dispositionalism is not. Naive dispositionalism, according to Ellis, is the view that the world is ultimately something like a conglomerate of objects and their dispositions, and that, therefore, dispositions are the ultimate ontological units that explain events. Sophisticated dispositionalism, according to Ellis, supposes that, how things are disposed to behave depends also on what kinds of things they are, what kinds of property they have, and how these kinds of things and properties are placed in the natural kinds hierarchies to which they belong (Ellis 2005). Further, it supposes that at the top of each hierarchy of natural kinds there is a global kind. For example, ‘[t]he global natural kind in the category of substance is that of the physical system’ (Ellis 2005). Ellis continues, claiming that the PLA is of the essence of the global kind in the category of objects or substances. If this is so, then, of course, every continuing object must be Lagrangian, i.e. disposed to evolve in accordance with the principle of least action (Ellis 2005). Ellis concludes that, therefore, a sophisticated dispositionalist can accommodate the PLA and its metaphysical necessity