The illusion of reality: how (not) to think of hallucination

Defining hallucination is surprisingly difficult: most definitions either miss cases that clinicians consider hallucinations or include cases they do not. This paper first shows why existing accounts fail, then develops a new definition that captures all and only the cases clinicians classify as hallucinations. The key is clarifying two often vague ideas: that hallucinations have a 'sense of reality' and that they are 'perception-like'. By specifying exactly what these mean, the authors provide an account that matches clinical usage.

Study at a glance

Abstract

Abstract It is surprisingly difficult to provide an account of hallucination that captures all the cases that clinicians typically class as hallucinations, without at the same time admitting cases that would not typically be classed as such. Most attempts to specify exactly what a hallucination is supposed to be fails to meet at least one of these conditions, as we show in the first part of the paper. We then proceed to develop an account of hallucination that meets both conditions. Central to this account is a discussion of two key notions in much need of clarification: the notion that hallucinations have a ‘sense of reality’, and the notion that hallucinations are ‘perception-like’. Settling on the exact meaning of these two notions allows us to offer an account of hallucination that captures all cases typically classified as hallucination and only such cases.