ASTR 2110

Aristotle and Plato were both influential ancient Greek philosophers. While they made great contributions to the field of philosophy and politics, their views about the universe also had lasting impacts on Western history. In this blog, I want to share and compare the cosmologies put furth by the two philosophers based on what I learnt in another astronomy course.

Aristotle and Plato had different views on the structure and workings of the universe, which resulted in their differing cosmologies. Plato believed that the universe was divided into two realms, the world of the Forms, which was perfect and unchanging, and the physical world, which was an imperfect reflection of the Forms. He also believed in a geocentric model, where the Earth was at the center of the universe, and the stars and planets revolved around it in perfect, circular orbits.

Aristotle, on the other hand, believed that the physical world was comprised of four elements: earth, air, fire, and water. These elements had natural motions that resulted in the phenomena observed in the world. Besides the four elements, in the physical world, there was a fifth element in the celestial heaven, called ether. It was characterized by its perfect and unchanging nature, as well as its ability to transmit motion from one sphere to another. Interestingly, the concept of ether is still prevalent today to be included in many fictional movies and games as a type of substance with mysterious power. Moreover, Aristotle proposed a complex system in which the Earth was at the center of the universe, but with the moon and other celestial bodies rotating around it. He also believed that the universe was infinite and contained an unlimited number of spheres, each with its own celestial body.

In terms of their attitude toward the position of humankind in the universe, both philosophers believed that humans held a special place in the cosmos. However, they had different views on the nature of this specialness. Plato believed that the Forms were the true reality and that the physical world was an imitation of the Forms, with humans having a special connection to the Forms, but humankind cannot achieve perfectness in the physical world. In contrast, Aristotle believed that the physical world was the true reality and that humans held a special place in the universe because of their ability to reason and understand the natural world.

Aristotle’s cosmology became prevalent over Plato’s mainly for two reasons:

1. It offered a more detailed and logically consistent explanation of the natural world. Aristotle’s system was also more in line with the observations of the time, and his ideas were further developed and supported by later philosophers and scientists, such as Ptolemy.
2. Aristotle’s cosmology was welcomed by Christianity because it provided a framework that was compatible with the religious beliefs of the time. Aristotle’s system placed humans and the Earth at the center of the universe, which was seen as a reflection of humanity’s special place in the divine order.