Information and \sigma -algebras

In this work, we clarify the relationship between the information that an agent receives from a signal, from an experiment or from his own ability to determine the true state of nature that occurs and the information that an agent receives from a $\sigma $ -algebra. We show that, for countably generated $\sigma $ -algebras, the larger it is, the larger the information is. The same is true for general $\sigma $ -algebras after the removal of a negligible set of states.