Of all the abuses of mathematics, of all the abuses of science generally, no single phenomenon causes more misunderstanding than coincidences.
—Dewdney (1993, p. 40)
Strange coincidence, that every man whose skull has been opened had a brain!
—Wittgenstein (1953/1972, p. 28)
Coincidences can be fascinating, entertaining, intriguing—and sometimes very informative. We are fascinated when we bump into someone from our home town in a foreign city, when we learn that a new acquaintance has three children with the same first names as our own, or when we hear from an almost forgotten friend about whom we have just dreamed. Journalists sometimes entertain us with accounts of coincidental similarities between famous persons. Parallels in the lives of John F. Kennedy and Abraham Lincoln, their assassins and the details of their assassinations, have captured the attention and imagination of several writers (Lattimer, 1966, 1980;Russel, 1973;T. R. Turner, 1993; Wrone, 1981):
Lincoln was elected in 1860, Kennedy in 1960. Both were deeply involved in the civil rights struggle. The names of each contain seven letters. The wife of each president lost a son when she was First Lady. Both Presidents were shot on a Friday. Both were shot in the head, from behind, and in the presence of their wives. Both presidential assassins were shot to death before they could be brought to