a dozen or more, are considering highly complicated questions, such
as the House Naval Committee discuss when officers are called to
testify before them, no two of the twenty congressmen can form the
same mental picture when an officer uses the word--say "fleet."
The reason is simply that very few of the congressmen hearing that
word have ever seen a fleet; none of them know exactly what it is,
and every one forms a picture which is partly the result of all
his previous education and experience; which are different from
the previous education and experience of every other congressman
on the committee. Furthermore, no one of the officers uses words
exactly as the other officers do; and the English language is too
vague (or rather the usual interpretation put on words is too vague)
to assure us that even ordinary words are mutually understood. For
instance, the question is asked: "Do you consider it probable that
such or such a thing would happen?" Now what does the questioner
mean by "probable," and what does the officer think he means?
Mathematically, the meaning of "probable" is that there is more
than 50 per cent of chance that the thing would happen; but who
in ordinary conversation uses that word in that way? That this is
not an academic point is shown by the fact that if the answer is
"no" the usual inference from the answer is that there is no need
for guarding against the contingency. Yet such an inference, if
the word "probable" were used correctly by both the questioner and
the answerer, would be utterly unjustified, because the necessity
for taking precautions against a danger depends not so much on its
probability or improbability, as on the degree of its probability;
and to an equal degree on the greatness of the danger that impends.
If the occurrence of a small mishap has a probability say of even
75 per cent, there may be little necessity of guarding against
it; while if the danger of total destruction has a probability
as low as even 1 per cent, we should guard against it sedulously.

The more complicated the question, the more elements involved, the
more difficult it is to settle it wisely by mere discussion. The
effort of the imagination of each person must be directed not so
much to getting a correct mental picture of what the words employed
describe, as to getting a correct picture of what the person using
the words desires them to describe. Any person who has had experience
in discussions of this ch