PUBLIC OPINION by WALTER LIPPMANN TO FAYE LIPPMANN ...

4. It is _fit_ to be true;
5. It _ought_ to be true;
6. It _must_ be true;
7. It _shall_ be true, at any rate true for me."
And, as he added in another place, [Footnote: _A Pluralistic
Universe_, p. 329.] "your acting thus may in certain special cases
be a means of making it securely true in the end." Yet no one would
have insisted more than he, that, so far as we know how, we must avoid
substituting the goal for the starting point, must avoid reading back
into the present what courage, effort and skill might create in the
future. Yet this truism is inordinately difficult to live by, because
every one of us is so little trained in the selection of our samples.
If we believe that a certain thing ought to be true, we can almost
always find either an instance where it is true, or someone who
believes it ought to be true. It is ever so hard when a concrete fact
illustrates a hope to weigh that fact properly. When the first six
people we meet agree with us, it is not easy to remember that they may
all have read the same newspaper at breakfast. And yet we cannot send
out a questionnaire to 816 random samples every time we wish to
estimate a probability. In dealing with any large mass of facts, the
presumption is against our having picked true samples, if we are
acting on a casual impression.
9
And when we try to go one step further in order to seek the causes and
effects of unseen and complicated affairs, haphazard opinion is very
tricky. There are few big issues in public life where cause and effect
are obvious at once. They are not obvious to scholars who have devoted
years, let us say, to studying business cycles, or price and wage
movements, or the migration and the assimilation of peoples, or the
diplomatic purposes of foreign powers. Yet somehow we are all supposed
to have opinions on these matters, and it is not surprising that the
commonest form of reasoning is the intuitive, post hoc ergo propter
hoc.
The more untrained a mind, the more readily it works out a theory that
two things which catch its attention at the same time are causally
connected. We have already dwelt at some length on the way things
reach our attention. We have seen that our access to information is
obstructed and uncertain, and that our apprehension is deeply
controlled by our stereotypes; that the evidence available to our
reason is subject to illusions of defense, prestige, morality, space,