The Proposition
In order to induce argument, there must be a proposition. A proposition in argument is a statement—a declarative sentence—concerning the truth or expediency of which there may be two opinions. Notice that not every declarative statement is a proposition for argument. "The sun rises" is not a statement about which there can be any varying opinions. It is not a proposition for argument. But "Missionaries should not be sent to China," and "John Doe killed Simon Lee," are statements admitting of different opinions and beliefs. They are propositions for argument. No sane person would argue about such a statement as "Missionaries are sent to China," nor would any one waste time on such a statement as "Some day a man named John Doe will kill a man named Simon Lee."
Although in common language we speak of arguing a question the student must remember that such a thing is impossible. You cannot argue about a question. Nor can you argue about a subject or a topic. The only expression about which there can be any argument is a proposition. The question must be answered. The resulting statement is then proved or disproved. The topic must be given some definite expression in a declarative sentence before any real argument is possible.
Even when the matter of argument is incorrectly phrased as a topic or question you will find almost immediately in the remarks the proposition as a sentence. "Should women vote?" may be on the posters announcing an address, but the speaker will soon declare, "Women should vote in all elections in the United States upon the same conditions that men do." That is the proposition being argued; the question has been answered.