In philosophical literature the issue of beliefs has been identified historically with David Hume and common sense. Beliefs are dynamic systems and its resignification is constant. Charles Sanders Pierce would interpret the fixation of beliefs, as those ones which are fixed by means of art, being this a method well-tuned with science. Truths established in beliefs are always probable and dependent on the degree of utility they have. The degree of utility is complemented with comprehension, explanations have multiple causes.