Peter Menzies

(1953 - 2015)

Delusional beliefs have sometimes been considered as rational inferences from abnormal experiences. We explore this idea in more detail, making the following points. Firstly, the abnormalities of cognition which initially prompt the entertaining of a delusional belief are not always conscious and since we prefer to restrict the term “experience” to consciousness we refer to “abnormal data” rather than “abnormal experience”. Secondly, we argue that in relation to many delusions (we consider eight) one can clearly identify what the abnormal cognitive data are which prompted the delusion and what the neuropsychological impairment is which is responsible for the occurrence of these data; but one can equally clearly point to cases where this impairments is present but delusion is not. So the impairment is not sufficient for delusion to occur. A second cognitive impairment, one which impairs the ability to evaluate beliefs, must also be present. Thirdly (and this is the main thrust of our chapter) we consider in detail what the nature of the inference is that leads from the abnormal data to the belief. This is not deductive inference and it is not inference by enumerative induction; it is abductive inference. We offer a Bayesian account of abductive inference and apply it to the explanation of delusional belief.

This book advocates dispositional essentialism, the view that natural properties have dispositional essences.1 So, for example, the essence of the property of being negatively charged is to be disposed to attract positively charged objects. From this fact it follows that it is a law that all negatively charged objects will attract positively 10 charged objects; and indeed that this law is metaphysically necessary. Since the identity of the property of being negatively charged is determined by its being related in a certain way to the property of being positively charged, in any world in which these properties exist they must be related so that all negatively charged objects attract positively charged objects. 15 Bird opposes his dispositional essentialism to the view that properties are categorical in nature, with their identities grounded in quiddities that are not exhausted by their relations to other properties. The main exponents of this view are D.M. Armstrong and David Lewis. They take the laws of nature to be contingent though they entertain very different views about their nature: Armstrong is a necessitarian 20 about laws, taking them to be relations of nomic necessitation between universals, while Lewis is a Humean about laws who takes them to be a special kind of regularity. The book is a sustained defence of the dispositional essentialist conception of properties and laws against the competing conceptions espoused by Armstrong and Lewis. One rough way to characterize the difference between these conceptions is to say that 25 the categoricalist sees properties as passive and inert with the laws of nature being fixed independently of the nature of properties whereas, in contrast, the dispositional essentialist sees properties as active potencies from which the laws of nature automatically spring. A slightly more tendentious way to express the difference is to say, as Bird does, that the categoricalist views embrace the Humean doctrine that there are no 30 necessary connexions in nature, while the dispositional essentialist view, on the other hand, repudiates this doctrine..

I argue that philosophers and psychologists have been premature in dismissing the possibility that the causal concept is analytically tied to the concept of counterfactual dependence. I argue that if we understand the notion of counterfactual dependence in a suitably enriched way, we can see that some examples that purport to show the difference between causation and counterfactual dependence do not in fact show this. In spelling out this enriched conception of counterfactual dependence, I draw on work in cognitive psychology on counterfactual availability, or the conditions under which people spontaneously generate counterfactuals or evaluate particular counterfactuals as true. I shall rely, in particular, on studies by Kahneman & Tversky, Kahneman & Miller, and Hart & Honoré that attend to the important role that the concepts of norms, normal conditions, and interventions play in our counterfactual reasoning. I argue that concept of counterfactual dependence, enriched in the way I suggest, is a more apt tool for analysing the concept of causation.

This book advocates dispositional essentialism, the view that natural properties have dispositional essences. 1 So, for example, the essence of the property of being negatively charged is to be disposed to attract positively charged objects. From this fact it follows that it is a law that all negatively charged objects will attract positively charged objects; and indeed that this law is metaphysically necessary. Since the identity of the property of being negatively charged is determined by its being related in a certain way to the property of being positively charged, in any world in which these properties exist they must be related so that all negatively charged objects attract positively charged objects.Bird opposes his dispositional essentialism to the view that properties are categorical in nature, with their identities grounded in quiddities that are not exhausted by their relations to other properties. The main exponents of this view are D.M. Armstrong and David Lewis. They take the laws of nature to be contingent though they entertain very different views about their nature: Armstrong is a necessitarian about laws, taking them to be relations of nomic necessitation between universals, while Lewis is a Humean about laws who takes them to be a special kind of regularity. The book is a sustained defence of the dispositional essentialist conception of properties and laws against the competing conceptions espoused by Armstrong and Lewis. One rough way to characterize the difference between these conceptions is to say that the categoricalist sees properties as passive and inert with the laws of nature being fixed independently of the nature of properties whereas, in contrast, the dispositional essentialist sees properties as active potencies from which the laws of nature automatically spring. A slightly more tendentious way to express the difference is to say, as Bird does, that the …

Modal functionalism is the view that talk about possible worlds should be construed as talk about fictional objects. The version of modal fictionalism originally presented by Gideon Rosen adopted a simple prefixing strategy for fictionalising possible worlds analyses of modal propositions. However, Stuart Brock and Rosen himself in a later article have independently advanced an objection that shows that the prefixing strategy cannot serve fictionalist purposes. In this paper we defend fictionalism about possible worlds by showing that there are other strategies besides the prefixing strategy for fictionalising talk about possible worlds, and that these strategies are proof against the objection advanced by Brock and Rosen

Several different approaches to the conceptual analysis of causation are guided by the idea that a cause is something that makes a difference to its effects. These approaches seek to elucidate the concept of causation by explicating the concept of a difference-maker in terms of better-understood concepts. There is no better example of such an approach than David Lewis’ analysis of causation, in which he seeks to explain the concept of a difference-maker in counterfactual terms. Lewis introduced his counterfactual theory of causation with these words: 'We think of a cause as something that makes a difference, and the difference it makes must be a difference from what would have happened without it. Had it been absent, its effects—some of them, at least, and usually all—would have been absent as well.' (Lewis 1973b: pp. 160-1) According to Lewis, a cause c makes a difference to an effect e in the sense that if the cause c had not occurred, the effect e would not have occurred either. All we shall see in section 2, Lewis’ theory says there is more to the concept of causation than this counterfactual condition. Lewis is on the right track, I think, in saying that we think of a cause as something that makes a difference and that this thought is best explicated in terms of counterfactual concepts. However, I shall argue that the particular way in which Lewis spells out the concept of a cause as difference-maker is unsatisfactory. For Lewis’ articulation of this concept is distorted by a specific metaphysical assumption: specifically, that causation is an absolute relation, specifiable independently of any contextual factors. The distortion induced by this assumption is reflected in the undiscriminating manner in which his theory generates countless causes for any given effect. However, commonsense judgement is much more discriminating about causes than Lewis’ theory. Accordingly, I claim that Lewis' analysis faces the problem of profligate causes and I outline some specific problem cases in section 3..

Recently, a number of philosophers of science have claimed that much explanation in the sciences, especially in the biomedical and social sciences, is mechanistic explanation. I argue the account of mechanistic explanation provided in this tradition has not been entirely satisfactory, as it has neglected to describe in complete detail the crucial causal structure of mechanistic explanation. I show how the interventionist approach to causation, especially within a structural equations framework, provides a simple and elegant account of the causal structure of mechanisms. This account explains the many useful insights of traditional accounts of mechanism, such as Carl Craver's account in his book Explaining the Brain , but also helps to correct the omissions of such accounts. One of these omissions is the failure to provide an explicit formulation of a modularity constraint that plays a significant role in mechanistic explanation. One virtue of the interventionist/structural equations framework is that it allows for a simple formulation of a modularity constraint on mechanistic explanation. I illustrate the role of this constraint in the last section of the paper, which describes the form that mechanistic explanation takes in the computational, information-processing paradigm of cognitive psychology