Abstract
I present a novel argument against the epistemic conception of perception (ECP) according to which perception either is a form of knowledge or puts the subject in a position to gain knowledge about what is perceived. ECP closes the gap between a perceptual experience that veridically presents a given state of affairs and an experience capable of yielding the knowledge that the state of affairs obtains. Against ECP, I describe a particular case of perceptual experience in which the following triad of claims is true: (i) The experience presents a given state of affairs (it has propositional content); (ii) The experience is veridical; (iii) The experience cannot yield the knowledge that the state of affairs obtains (even in the absence of relevant defeaters). This case involves an empirically well-studied phenomenon, namely perceptual hysteresis, which involves the maintenance of a perceptual experience with a relatively stable content over progressively degrading sensory stimulations.
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Notes
Although perceptual hysteresis in such an experiment is typically quite high, it may vary across subjects. For some indication that perceptual hysteresis is significantly higher in schizophrenia (and especially for hallucinatory patients), see Martin et al. (2014), which adapts Kleinschmidt et al. (2002)’s paradigm to the auditory case.
For discussion, see Engel (2007, Chap. 3) and Dokic and Égré (2009). Roughly speaking, a belief is safe only if its content is true in all nearby worlds (see Williamson 2000, pp. 147–149). On an alternative definition, a belief is safe only if the method that produced it does not produce a false belief in any nearby world (see Sainsbury 1996).
In the study of Martin et al. (2014), 40 % of schizophrenic patients report hearing the signal when the signal-to-noise ratio has gone down to \(-\)30 db. At this point, they clearly have auditory hallucinations, perhaps even “non-veridical” ones in Lewis’s sense (although the signal is still physically there, it is much below the normal threshold of audition).
See for instance what Bernecker (2009, Sect. 3.2) calls “the principle of continuous justification”.
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Acknowledgments
Thanks to two anonymous referees of this journal, and to Pascal Engel for stimulating ongoing discussions on knowledge. This work has been supported by the following two grants: ANR-10-LABX-0087 IEC and ANR-10-IDEX-0001-02 PSL.
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There are no conflicts of interest with respect to the present paper.
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Dokic, J. Knowledge, perception, and the art of camouflage. Synthese 194, 1531–1539 (2017). https://doi.org/10.1007/s11229-015-0758-5
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DOI: https://doi.org/10.1007/s11229-015-0758-5