Axioms are propositions that are true by definition. In other words, they can not be falsified by empirical methodology. Some say that this poses a problem because in being true by definition, their argumentation is circular or tautological. Examples of axioms are for example algebraic formulas, like (a+b)(a+b) is equal to a squared+ ab squared+b squared. In Austrian economics, private property is considered to be axiomatic, because any intent to try to falsify it, only proves its existence.