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The Causal Theory of Veridical Hallucinations

Published online by Cambridge University Press:  30 January 2009

Sean Wilkie
Sean Wilkie
Affiliation:
Ystalyfera
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Extract

At the very heart of the causal theory of perception are the peculiar examples sometimes called veridical hallucinations. These examples originate with Grice, who used them to prove ‘conclusively’ that when we say, for example, ‘Jane saw John’, we mean that John is the cause of certain visual experiences or impressions had by Jane.

Type
Articles
Information
Philosophy , Volume 71 , Issue 276 , April 1996 , pp. 245 - 254
Copyright
Copyright © The Royal Institute of Philosophy 1996

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References

1 Grice, H. P., ‘The Causal Theory of Perception’, abridged in J.Dancy (ed.), Perceptual Knowledge (Oxford University Press, 1988). Whenever in what follows a page number is simply inserted in brackets, the reference is to this article.Google Scholar

2 Strawson, P. F., ‘Causation in Perception’, Freedom and Resentment and Other Essays (London: Methuen, 1974), 68.Google Scholar See also Wiggins, D., ‘Freedom, Knowledge, Belief and Causality’ in G.Vesey (ed.), Knowledge and Necessity (London, 1970), 137.Google Scholar

3 Jane need not be terribly precise about John's location. She might have caught a glimpse of him in a crowd. For the purpose of the argument, however, I shall ignore this or any other complications—such as seeing John on television—and treat the example as one where John is directly in front of Jane, inclear view, ten feet away.)

4 Hyman, J., ‘The Causal Theory of Perception’, The Philosophical Quarterly 42 (1992), 278.CrossRefGoogle Scholar

5 Strawson, , for example, treats the causal theory as part-and-parcel of a distinction between ‘objects’ and ‘experiences’ that creates a ‘pre-theoretical’ schema in which ‘independently existing things’ are causally responsible for our ‘fleeting perceptions’ (‘Perception and its Objects’, in Dancy (ed.), op. cit., 103-4).Google Scholar

6 Grice (69–70) felt obliged to ‘leave the realm of fantasy’ and introduce a second example involving nothing more technologically advanced than mirrors. See below (fn. 13).

7 Price, H. H., Perception (London: Methuen, 1932), 26.Google Scholar

8 Ibid.

9 Rickman, H. P., Preface to Philosophy (London: Routledge & Kegan Paul, 1964), 4: I citethis as a random example of a more or less generic view of where philosophical problems come from.Google Scholar

10 See, for example, Feyerabend, P., Against Method (London: Verso, 1988), 22Google Scholar: ‘our habit of saying… “the table seems to be brown” when… we feel unsure in our capacity of observation expresses the belief… that some of our sensory impressions are veridical while others are not.’ This is a fine example of ‘the curious turn of phrase’ (see below, §2); at this stage it is uncertain whether everything or nothing turns on the phrase ‘sensory impressions’. See also Dretske, F., Knowledge and the Flow of Information (Oxford: Blackwell, 1981), 142Google Scholar, and Shoemaker, S., ‘Qualia and Consciousness’, Mind 100 (1991), 520.Google Scholar

11 Curiously, there is at least some experimental evidence, ‘relevant’ to veridical hallucination, cited in Merleau-Ponty, M., phenomenology of Perception, trans. Smith, Colin, (London: Routledge and Kegan Paul, 1962), 334–45.Google Scholar This instructing, if occasionally opaque, discussion of the failure of traditional theories to come to terms with hallucinatory phenomena refers to the work of Zucker, (Experimentelles uber Sinnestauschungen, 706–764). A guinea pig was placed in the hand of a subject who, in delirium tremens, thought that the doctor's hand was a guinea pig. This subject immediately realized what the doctor's hand really was. A man wearing the appropriate clothing and adopting the general bearing described by a schizophrenic patient was placed in the spot beneath the window where the schizophrenic had previously reported seeing a man. The schizophrenic was astonished: looking carefully, he said that there was someone there, but that it was ‘somebody else’. A woman with senile dementia, who complained of a layer of powder on her bed-sheet, was startled to find a thin layer sprinkled there, and said that it was damp while the ‘other’ was dry. Finally, patients immediately distinguished tactile hallucinations of pricking or electric shocks from actual experiences of them: when the doctors administered injections or shocks, the patients told them that they (the doctors) were the cause of these sensations. Is this merely evidencethat veridical hallucinations are very difficult to engineer? I feel that, in thesecases, Zucker was not simply unlucky.Google Scholar

12 Pears, D. ‘The Causal Conditions of Perception’, Synthese 33 (1976), 25.CrossRefGoogle Scholar

13 Grice's second thought experiment (see fn. 6 above) involves a mirror, placed between the subject and a pillar, and showing the reflection of a second, identical pillar which (given that the subject does not know he is looking in the mirror) appears to be located exactly where the first is situated. When the mirror is revealed, the ‘ordinary conclusion’, of course, is that we saw the second pillar and not the first. It is ‘extremely tempting’, says Grice (70), ‘to explain this linguistic fact by saying that the first pillar was, and the second was not, causally irrelevant to the way things looked’. The idea that this is a ‘linguistic fact’ is our old friend, the curious turn of phrase, again. It is quite plausible to say that mastery of visual concepts (and mastery of mirrors) involves understanding that mirrors hide things in the same way as do other solid objects; that you can't see through them. And it is sufficient for Grice to tell us that the second pillar is reflected in the mirror: there is no need to invoke its ‘causal relevance’ in order to explain why that pillar is seen.

14 Moore, G. E., Some Main Problems of Philosophy (London: Allen and Unwin, 1953), 29.Google Scholar

15 Strawson, ‘Causation in Perception’,70.

16 As, for instance, Child does, William. See ‘Vision and Experience’, The Philosophical Quarterly 42 (1992), 311.Google Scholar

17 I observe, first, that, beneath the practical preferences, Jane seeing (or not seeing) John is tautologically equivalent to John being seen (or not seen) by Jane, and, secondly, that neither appears to be treated as an action. It is not impossible that John's causal priority should be implicit in these or other things that we say and do, but it is an idle hypothesis that these are observations of ‘surface grammar’ only, when the only evidence of a deeper layer of theory derives, not from what we ordinarily say and do, but from what philosophers say we ordinarily say and do.

18 Searle, J., Intentionality (Cambridge University Press, 1983), 44.Google Scholar

19 Hyman, 291.