Pragmatic aspect of information is the hardest to evaluate. The paper discusses various ways to estimate the amount of information. As a start point we take Shannon approach where no semantic aspects are taken into account. Such measure widely criticised in literature (Dretske, Mazur, Floridi and others) needs refinement concerning at least two aspects of information – its precision level and its usefulness for the adequate purpose.
Mazur’s critique concentrates on the precise separation of the coding system, which conveys elements of the knowledge of the recipient prior to the received message. Semantic approach to information (Carnap and Bar-Hillel, Dretske, Floridi) concentrates on the evaluation of the amount of information relative to the context of the background knowledge of the recipient.
Floridi’s approach is especially interesting as it concentrates on the evaluation of fuzzy information compared to the precise one. There remains, however still undiscovered field of comparison of different contexts to which the information is actually related. Some suggestions by the author and J. Płazowski can be taken as an estimation of such measure.