2. Was there any coincidence between the hallucination and facts at
the time unknown to you?
The majority of sane people will be able to answer the first
question in the negative.
Of those who answer both questions in the affirmative, several
things are to be said. First, we must allow for jokes, then for
illusions of memory. Corroborative contemporary evidence must be
produced. Again, of the 20,000, many are likely to be selected
instances. The inquirer is tempted to go to a person who, as he or
she already knows, has a story to tell. Again, the inquirers are
likely to be persons who take an interest in the subject on the
_affirmative_ side, and their acquaintances may have been partly
chosen because they were of the same intellectual complexion. {194b}
All these drawbacks are acknowledged to exist, and are allowed for,
and, as far as possible, provided against, by the very fair-minded
people who have conducted this inquisition. Thus Mr. Henry
Sidgwick, in 1889, said, 'I do not think we can be satisfied with
less than 50,000 answers'. {195} But these 50,000 answers have not
been received. When we reflect that, to our knowledge, out of
twenty-five questions asked among our acquaintances in one place,
_none_ would be answered in the affirmative: while, by selecting,
we could get twenty-five affirmative replies, the delicacy and
difficulty of the inquisition becomes painfully evident. Mr.
Sidgwick, after making deductions on all sides of the most
sportsmanlike character, still holds that the coincidences are more
numerous by far than the Calculus of Probabilities admits. This is
a question for the advanced mathematician. M. Richet once made some
experiments which illustrate the problem. One man in a room thought
of a series of names which, ex hypothesi, he kept to himself. Three
persons sat at a table, which, as tables will do, 'tilted,' and each
tilt rang an electric bell. Two other persons, concealed from the
view of the table tilters, ran through an alphabet with a pencil,
marking each letter at which the bell rang. These letters were
compared with the names secretly thought of by the person at neither
table.