ere
had been a conspiracy to commit it.[47]

The strength of reasoning from circumstantial evidence lies in the
number and the diversity of the points of similarity to the point in
hand. If there are few of them, the possibility of coincidence
increases, as it also does when the points of similarity come from the
same source or are of the same nature. This possibility of coincidence
is a good rough test of the value of reasoning from circumstantial
evidence: where the theory of a coincidence would stretch all
probabilities one may safely leave it out of account.

In practice the argument from circumstantial evidence is more frequent
in the experience of lawyers than in that of other men; but sooner or
later everybody has to pass on such reasoning, for wherever direct
evidence is out of the question it may be necessary to piece the
situation together by circumstantial evidence. There is some prejudice
against such evidence, springing from reported cases of miscarriage of
justice in convictions based on it. Such cases, however, are very rare
in reality, and probably do not equal in number the cases in which
mistaken or false direct testimony has caused injustice.

46. Some Pitfalls of Reasoning--Ambiguity. I have already spoken of
some of the dangers to which reasoning is subject--false analogy, faulty
generalization of various kinds, and various sins against the rules of
the syllogism. There are still a few general dangers to speak about. It
should be noted that the various kinds of fallacies run into each other,
and not infrequently a given piece of bad reasoning can be described
under more than one of them.

Of all the sources of faulty and misleading reasoning, ambiguity is the
most fruitful and the most inclusive.

It springs from the facts that words, except those which are almost
technically specific, are constantly used in more than one sense, and
that a great many of the words which we use in everyday life are
essentially vague in meaning. Such common words as "liberty," "right,"
"gentleman," "better," "classic," "honor," and innumerable others each
need a treatise for any thorough definition; and then the definition, if
complete, would be largely a tabulation of perfectly proper senses in
which the words can be used, or a list of the ways in which different
people have used them. Besides this notorious vagueness of many common
words, a good many words, as I have already shown (p. 54), have two or
more dist