Axioms are statements that cannot be denied or refuted, because the very act attempting to do so would lead to self-contradication.  An example is the foundation of praxeology (the logic of action): "Human action exists."  This statement is true, and cannot be refuted, because the very attempt to do so is itself human action.  From this axiom we can logically deduce other things, e.g. "human action is purposeful behavior," "it si directed toward attainment of an end or goal," etc.

Thus the foundations for economics are laid, and we cann eventually logically deduce things like the law of marginal utility and a theory of the business cycle.