Historical sciences as cosmology, historical geology and paleontology study past entities, events and processes of their respectives objects of study (the universe, the planet earth, organisms). All this objects of study suffer historical process that destroy information to present scientific observers, difficulting the contrastability of hypotheses, despite this, historical sciences had been relatively successful in creating knowledge of their domain of facts. This confidence in the plausibility of studying the past has yet not arrived in archaeology, where some forms of extreme skepticism about the posibility of obtaining knowledge on past social systems still prevail.