The frequently used term "certainty" plays in the human life an important role, especially in specifying the goals of human activities. The presented study distinguishes two different meanings of this term: the certainty as a state of the mind and the certainty of anything, i.e. the certainty connected with a set of specific conditions. A certainty in the former meaning is usually presented as an important component of some ideologies. As an explanatory model of the certainty of anything, there could be applied the approaches developed in the sphere of intensional or modal logics, especially the concept of epistemic attitudes. The contemporary scientific and technological thinking usually justifies an acceptable model od epistemic attitudes by means of various measures based on the scheme of decreasing uncertainty or, as it is typical for information models, by means of decreasing entropy level.