A scientific theory is a deductive theory, in that, its content is based on some formal system of logic and that some of its elementary theorems are taken as axioms. In a deductive theory, any sentence which is a logical consequence of one or more of the axioms is also a sentence of that theory. Theories are intended to be an accurate, predictive description of the natural world. However, it is sometimes not clear whether the conclusions derived from the theory inform us about the nature of the world, or the nature of the theory.