Having determined what the issues are, and having shown the audience
why the establishment of these issues should logically win belief in
your proposition, all that remains is to prove the issues.

Now it is clear that neither the audience nor the judges can be led to
agree with us and to accept our issues as proved, by our telling them
that we should like to have them believe in the soundness of our
views. Neither can we succeed in convincing them by telling them that
they ought to believe as we wish. The modern audience is not to be
cajoled or browbeaten into belief. How, then, are we to persuade our
hearers to accept our assertions as true? The only method is to give
them what they demand--reasons. We must tell _why_ every statement is
true. This process of telling why the issues are true so effectively
that the audience and judges believe them to be true is called the
_proof_.

Naturally, the reasons that we give in support of the issues will be
no better than the issues themselves, unless we know what reasons the
audience will believe. And how are we to know what reasons the
audience will believe? We can best answer that question by determining
why we ourselves believe those things which we accept. Why do we
believe anything? We believe that water is wet; the sky, blue; fire,
hot; and sugar, sweet, because in our _experience_ we have always
found them so. These things we believe because we have _experienced_
them ourselves. There are other things that we believe in a similar
way. We believe that not every newspaper report is reliable. We
believe that a statement in the _Outlook_, the _Review of Reviews_, or
the _World's Work_ is likely to be more trustworthy than a yellow
headline in the _Morning Bugle_. Our own experience, plus what we have
heard of the experience of others, has led us to this belief. But