There are different classes of statements / questions. Here are the ones I can think of, off the top of my head.
1. Facts, which are impartial. "The population of the US in July 2008 was estimated at 303,824,640" is a fact.
2. Opinions, which ideally are based on fact. "The US is / is not overpopulated" is an opinion.
3. Preferences, which are not susceptible to fact-based logic. "I don't want to have children" is a preference.
4. Emotions, which may be susceptible to fact-based logic, but usually aren't. "When you say that anyone who doesn't want children is selfish and unthinking it hurts me" is an emotion (or anyway an expression of one).
What are some others?
