St. Thomas Aquinas Summary

1. In the Summa Theologica, St. Thomas Aquinas concluded that our knowledge originates in sense perception, and that the purpose of knowledge is to be the entire universe through natural being, or esse intentionale. Aquinas said that knowledge must be universal, unchanging, and necessary. Being is knowing, and this includes being the entire material universe by knowing the entire material universe. The purpose of knowledge also includes being God, or knowing God. Knowing God consists of philosophy as a cause, theology as revealed, and beatific vision as God, which can only occur after death – all of which is achievable only through the actions of God. Aquinas concludes that a person cannot achieve the purpose of knowledge alone, we

Aquinas begins one of his arguments for the purpose of knowledge by distinguishing two types of perfection, existence and “perfection belonging to one thing is found in another” (Aquinas, q.2 a. 2) essentially, knowledge. In the first type of perfection, existence, something would be perfect according to its own species. The species, or forms, are perfect from the act of their existence. There are four forms: human, animal, plant and inanimate; each of these are perfect in their existence. Since each species has its own perfection, “the perfect falls short of absolute perfection to the extent that perfection is found in other species” (Aquinas De veritate q.2,a.2), meaning that no form can hold absolute perfection. In this definition of knowledge where knowing conforms to being, an acorn, for example, is perfect when it can grow, reproduce and nourish, reaching its final cause. But it is only the perfection of an oak tree (plant). The oak tree cannot have the perfection of a human. Perfection is limited to each individual form, because the whole of perfection is more perfect than the perfection of each

Aquinas uses both sensation and intellect in knowledge. One strength in Aquinas’ argument is his use and combination of the past philosophers to make a more coherent argument. There are also weaknesses in Aquinas’s argument. Aquinas would even admit this. He would admit that he made a mistake putting physics in the first method of knowledge, where separation of form from matter to focus on form with the subject matter of natural things. His methodology means there would be no unified terrestrial and celestial physics, or even a unified terrestrial physics. Aquinas would first admit that his physics was completely wrong. He would correct himself today by saying that there is no form in physics. In reality there is form, humans just do not think about