Peter Menzies

(1953 - 2015)

In the history of modern philosophy systematic connections were assumed to hold between the modal concepts of logical possibility and necessity and the concept of conceivability. However, in the eyes of many contemporary philosophers, insuperable objections face any attempt to analyze the modal concepts in terms of conceivability. It is important to keep in mind that a philosophical explanation of modality does not have to take the form of a reductive analysis. In this paper I attempt to provide a response-dependent account of the modal concepts in terms of conceivability along the lines of a nonreductive model of explanation

You are asked to call out the letters on a chart during an eyeexamination: you see and then read out the letters ‘U’, ‘R’, and ‘X’. Commonsense says that your perceptual experiences causally control your calling out the letters. Or suppose you are playing a game of chess intent on winning: you plan your strategy and move your chess pieces accordingly. Again, commonsense says that your intentions and plans causally control your moving the chess pieces. These causal judgements are as plain and evident as any can be

The basic idea of counterfactual theories of causation is that the meaning of causal claims can be explained in terms of counterfactual conditionals of the form “If A had not occurred, C would not have occurred”. While counterfactual analyses have been given of type-causal concepts, most counterfactual analyses have focused on singular causal or token-causal claims of the form “event c caused event e”. Analyses of token-causation have become popular in the last thirty years, especially since the development in the 1970's of possible world semantics for counterfactuals. The best known counterfactual analysis of causation is David Lewis's (1973b) theory. However, intense discussion over thirty years has cast doubt on the adequacy of any simple analysis of singular causation in terms of counterfactuals. Recent years have seen a proliferation of different refinements of the basic idea to achieve a closer match with commonsense judgements about causation.

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.

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.