Online research in philosophy

1923; Young, this volume); the Cotard delusion (Cotard, 1882; Berrios and Luque, 1995; Young, this volume); the Fregoli delusion (Courbon and Fail, 1927; de Pauw, Szulecka and Poltock, 1987; Ellis, Whitley and Luaute´, 1994); the delusion of mirrored-self misidentifi- cation (Foley and Breslau, 1982; Breen et al., this volume); a delusion of reduplicative param- nesia (Benson, Gardner and Meadows, 1976; Breen et al., this volume); a delusion sometimes found in patients suffering from unilateral neglect (Bisiach, 1988); and the delusions of alien control and of thought insertion, which are characteristic of schizophrenia (Frith, 1992).

The rationality debate centers on the meaning of deviations of decision makers' responses from the predictions/prescriptions of normative models. But for the debate to have significance, the meaning and functions of normative analysis must be clear. Presently, they are not, and the debate's persistence owes much to conceptual blur. An attempt is made here to clarify the concept of normative analysis.

It is often taken for granted in standard theories of interpretation that there cannot be intentionality without rationality. According to the background argument, a system can be interpreted as having irrational beliefs only against a general background of rationality. Starting from the widespread assumption that delusions can be reasonably described as irrational beliefs, I argue here that the background argument fails to account for their intentional description.

I argue that some cases of delusions show the inadequacy of those theories of interpretation that rely on a necessary rationality constraint on belief ascription. In particular I challenge the view that irrational beliefs can be ascribed only against a general background of rationality. Subjects affected by delusions seem to be genuine believers and their behaviour can be successfully explained in intentional terms, but they do not meet those criteria that according to Davidson (1985a) need to be met for the background of rationality to be in place.

The present article proposes a logical account of delusions, which are regarded as conclusions resulting from fallacious arguments. This leads to distinguish between primary, secondary, ..., n-ary types of delusional arguments. Examples of delusional arguments leading to delusion of reference, delusion of influence, thought-broadcasting delusion and delusion of grandeur are described and then analyzed. This suggests finally a way susceptible of improving the efficiency of cognitive therapy for delusions.

© 2004 by The Johns Hopkins University Press.

Stanford Encyclopedia Entry on Delusions.

Some otherwise rational people appear to believe strange things. Sometimes people believe that someone, usually a near relative or member of their family - often their spouse - has been replaced by an impostor. Sometimes people believe that they are dead. These two delusions – known as the Capgras and Cotard delusion respectively – are instances of monothematic delusions, for they are limited to very specific topics. Other monothematic delusions involve the delusion that one is being followed by known people in disguise (the Frégoli delusion), or that the person one sees in the mirror is someone else (mirrored-self misidentification). We will focus on the Capgras delusion.