The doctrine of great conjunctions, first theorized by the Arab astrologer Albumasar in the De magnis coniunctionibus (Book of Religions and Dynasties), is a form of general astrology characterized by the attempt to explain events affecting the Earth as a whole or in part (e.g. cataclysms – floods of water and fire, plagues, famine, etc. – the succession of civilizations, new empires, religions and prophets) as a consequence of the mean conjunctions of Saturn and Jupiter. The paper deals with Albert (...) the Great’s remarkable contribution to the medieval debate on great conjunctions by focusing on a few passages from his De causis proprietatum elementorum and his Politica commentary (II 6 and V 9). The potential and risks posed by this all-embracing explanation of natural phenomena and the human domain did not escape Albert the Great. He grasped the subversive character of the universal determinism underlying the great conjunctions, as well as their scientific value. The first selection of his texts, mainly taken from the De causis proprietatum elementorum, establishes the scientific nature of conjunctionist theory. They elucidate its complex and sophisticated notions, describe the effects of planetary conjunctions on the sublunary world, and oppose this theory to pseudoscientific explanations of natural processes. Albert also discusses the epistemological status of conjunctionist theory, clarifying its relationship to other branches of astrology. By contrast, the texts from the Politica commentary relate the great conjunctions to human history and political processes, exploring the conflict between astral determinism and human responsibility. (shrink)