(i) Crane (1) suggests we can save ourselves the trouble of looking at claims of the paranormal by invoking Hume's argument that it is more reasonable to believe that human error lies behind such claims than it is to 'believe that some fundamental law of nature has been disrupted'.
(ii) Hyman, for the purposes of dismissing apparently strong evidence for a 'remote viewing' capability (2, 3), asserts somewhat similarly that no matter how many investigations of the paranormal, carried out by whatever means, yield positive results, there will still be no proof that the alleged phenomena occur.
In response to enquiries as to why the usual mechanisms of science should be abandoned in this special context, our observer would be directed to study Soul Searching (Leaps of Faith in the U.S.) by Nicholas Humphrey (comment (i) comes from Crane's review of this book) in order to understand why claims of the paranormal are not taken seriously by scientists. But a subversive parapsychologist would suggest looking also at the review by Josephson (4), whereupon our friend would realise that Humphrey's arguments were flawed and hence of no value. He would study also some of the original research (5), and wonder whether possibly the scientists were making a monumental error in condemning it so vehemently.
That scientists at large do not come to the same conclusions as our mythical observer stems, I believe, from two main factors, whose existence mocks the claim of science to be the agent of unveiling the truth however strange that truth may appear: 'received knowledge', reinforced by the activities of propagandists; and the publishing policies of journals, which limit very effectively the acquaintance that the ordinary scientist has with parapsychological research, and thereby make informed assessment of the work in general effectively impossible.
To provide readers with a better perspective with which to evaluate the evidence, I append to this letter some key references. In addition, for the benefit of those with World Wide Web access I have created a parapsychology page with links to the text of some of these and to sites where more information may be obtained.
(1) Crane, T. Nature 379, 685 (1996)
(2) Lehrman, S. Nature 378, 525 (1995)
(3) The assessments of this research, including that of Hyman, can be found in J. Sci. Exploration, 10(1), 3-62 (1996); see also home page of Jessica Utts
(4) Josephson, B.D. Times Higher Educ. Supp. 1206, 19 (1995)
(5) Bem, D. J. and C. Honorton, Does psi exist? Replicable evidence for an anomalous process of information transfer, Psych. Bull. 115(1), 4-18 (1994); Utts, J., Replication and meta-analysis in parapsychology, Stat. Sci. 6, 363-403 (1991); D. I. Radin and R. D. Nelson, Evidence for consciousness-related anomalies in random physical systems, Found. Phys. 19, 1499-1514 (1989).
Brian D. Josephson
Cambridge CB3 0HE, U.K.