Mediaeval objections
How did John Gower define the limits of astrology?
Astrology
In the seventh century, Isidore of Seville argued in his "Etymologiae" that astronomy described the movements of the heavens, while astrology had two parts: one was scientific, describing the movements of the sun, the moon and the stars, while the other, making predictions, was theologically erroneous. In contrast, John Gower in the fourteenth century defined astrology as essentially limited to the making of predictions. The influence of the stars was in turn divided into natural astrology, with for example effects on tides and the growth of plants, and judicial astrology, with supposedly predictable effects on people. The fourteenth century skeptic Nicole Oresme however included astronomy as a part of astrology in his "Livre de divinacions". Oresme argued that current approaches to prediction of events such as plagues, wars, and weather were inappropriate, but that such prediction was a valid field of inquiry. However, he attacked the use of astrology to choose the timing of actions (so-called interrogation and election) as wholly false, and rejected the determination of human action by the stars on grounds of free will. The friar Laurens Pignon (c. 1368–1449) similarly rejected all forms of divination and determinism, including by the stars, in his 1411 "Contre les Devineurs". This was in opposition to the tradition carried by the Arab astronomer Albumasar (787-886) whose "Introductorium in Astronomiam" and "De Magnis Coniunctionibus" argued the view that both individual actions and larger scale history are determined by the stars.