But all this accounts for only part of the problem. To convict every medium of fraud is not a complete explanation of the appearance which this belief presented in its most characteristic form some decades ago, and still presents. It remains to account for the great success of the movement; for the fact that so many have been deceived and so few have really understood; to show why we are to believe the Seybert Commission, and not credit the countless miracle-mongers. This is psychologically the most interesting portion of the problem, and has been very successfully treated by Mrs. Sidgwick, Mr. Hodgson, and Mr. Davey, of the Society for Psychical Research.
There is a very broadspread notion that anybody can go to a spiritualistic séance and give a reliable opinion as to whether what he or she may chance to see is explicable as conjuring or not. Especially where the right to one's opinion is regarded as a corollary to the right of liberty, does this notion prevail. It is probably not an exaggeration to maintain that most such claimants are about as competent to form a trustworthy opinion on such a subject as they are to pronounce upon the genuineness of a Syriac manuscript. The matter is in some aspects as much a technical acquisition as is the diagnosticating of a disease. It is not at all to the discredit of any one's powers of observation or intellectual acumen to be deceived by the performances of a conjurer; and the same holds true of the professional part of mediumistic phenomena. Until this homely but salutary truth is impressed with all its importance upon all intending investigators, there is little hope of bringing about a proper attitude towards these and kindred phenomena. We believe that there will be an eclipse of the moon when the astronomer so predicts, not because we can calculate the time or even understand how the astronomer does it, but because that is a technical acquisition which he has learned and we have not; and so with a thousand other and more humble facts of daily life. Spiritualism, to a large extent, comes under the same category; and observers who have acquainted themselves with the possibilities of conjuring and the natural history of deception, who by their training and endowment have fitted themselves to be competent judges of such alleged ultra-physical facts--these persons have the same right to our confidence and respect as a body of chemists or physicians on a question within their province. It by no means follows that all scientists are fitted for an investigation of this kind, nor that all laymen are not; it does follow that a body of trained and able observers, who are aware of the possibilities of faulty observation and of the tendency to substitute hasty inference for fact, who know something about deception as a psychological characteristic, who have acquired or call to their aid the technical requisites for such an investigation, are better fitted to carry it to a logical outcome than are others, equally distinguished in other directions and equally able, if you will, but who have not these special qualifications. It follows that it is not fair for you to set up what you think you have seen as overthrowing their authority; even if you happen to be an unprejudiced and accurate observer and have weighed the probability of your observations being vitiated by one or other of the many sources of error in such observation, it is only a small fact, though of course one worthy of notice. There is no good reason why the average man should set so much store by his own impressions of sense, when the fallibility of other witnesses is so readily demonstrable.