How do social institutions exist? How do they direct our conduct? The Opposite Mirrors defends the thesis that the existence of institutions is a conventional matter. Ultimately they exist because we believe in their existence, and because they play a role in our practical reasoning. Human action necessarily has an unpredictable aspect; human institutions perform an important task by reducing uncertainty in our interactions. The author applies this thesis to the most important institutions: the law and the monetary system. In his analysis he connects many traditional topics of the philosophy of law, social philosophy and the philosophy of social sciences in a new way. He